Pediatric USMLE Part 4

751. A previously healthy 13-year-old girl presents to the emergency department with an acute onset of red urine after she played soccer in the morning. Her physical examination is unremarkable. Urinalysis shows a red color; pH, 6.2; specific gravity, 1.024; glucose, negative; blood, +4; protein, trace; nitrite, negative; leukocyte esterase, negative; white blood cell, 0/hpf; red blood cell, 1/hpf. Which of the following is the most likely explanation of the red urine?

752. A 1-month-old infant is seen in a well-baby clinic. The mother states that the baby is constipated and feeds poorly. On examination, he is jaundiced, has a large posterior fontanel and an umbilical hernia, and exhibits poor muscle tone. He has gained only 300 g since discharge from the normal newborn nursery. Which of the following is the most likely diagnosis?

753. A 7-year-old boy is referred for genetic testing because his father was diagnosed with medullary cancer of the thyroid. The father underwent a total thyroidectomy, and in the preoperative workup it was determined that he also had a pheochromocytoma, and that tumor was removed also. The father did not have parathyroid hyperplasia at the time, his phenotype was normal, and his final diagnosis was MEN-2A. The child is tested and found to have RET mutations in the peripheral white blood cells. The child has normal phenotype, normal levels of calcitonin, normal levels of catecholamines, metanephrines, and VMA, and normal levels of calcium and parathyroid hormone. Which of the following is the most appropriate management?

754. A 3-month-old male infant is brought to the emergency department by his mother because of difficulty in breathing. His mother was admitted in the hospital ten days ago due to a urinary tract infection, and he was cared for by his grandmother during that period. His mother had just been discharged from the hospital yesterday, and noticed that he was constipated and having difficulty with breastfeeding. On examination, he is afebrile. His pulse rate is 110/min, respirations are 36/min with shallow breathing efforts, and blood pressure is 90/50mm Hg. His weight is at the 35th percentile. Examination shows ptosis, dilated pupils with sluggish reaction to light, diminished deep tendon reflexes and decreased muscle tone. What is the most likely mechanism of his illness?

755. A 16-year-old College student presents to the physician's office because of ageneralized malaise, sore throat and fever for the past 2 to 3 days. She is given amoxicillin prescription. Twenty-four hours later, she develops a polymorphous rash over her entire body. She has taken amoxicillin in the past for sinus disease and never had any problem. What is the most likely organism that is responsible for her symptoms?

756. An otherwise healthy 17-year-old complains of swollen glands in his neck and groin for the past 6 months and an increasing cough over the previous 2 weeks. He also reports some fevers, especially at night, and possibly some weight loss. On examination, you notice that he has nontender cervical, supraclavicular, axillary, and inguinal nodes, no hepatosplenomegaly, and otherwise looks to be fairly healthy. Which of the following would be appropriate next step?

757. A 15-year-old girl has a round, 1-cm cystic mass in the midline of her neck, at the level of the hyoid bone. The mass is deep to the skin and moves slightly when the patient swallows. When the mass is palpated at the same time that the tongue is pulled, there seems to be a connection between the two. The mass has been present for at least 10 years, but only recently bothered the patient because it became infected. Which of the following is the most likely diagnosis?

760. A 2-year-old boy who emigrated from Eastern Europe 1 year ago is brought to the physician because of fever, cough, and night sweats for 3 weeks. The child's grandmother, who lives with him, has similar symptoms. The child's temperature is 39.2 C (102.6 F), Wood pressure is 110/65 mm Hg, pulse is 90/min, and respirations are 28/min. A Mantoux test is reactive, and a chest x-ray film shows a right middle lobe infiltrate and hilar lymphadenopathy. Which of the following is the most appropriate next step in diagnosis?

761. A 4-month-old infant is evaluated by a dermatologist because of thick, erythematous skin with fine scaling, principally involving his face. The mother reports that the infant is "always scratching his face." An older brother and a maternal uncle had a similar condition. Screening hematologic studies show the following: Erythrocyte count 5.1 million/mm3 Leukocyte count 12,000/mm3  Segmented neutrophils 80% Bands 5% Eosinophils 3% Basophils 1% Lymphocytes 5% Monocytes 6% Platelet count 35,000/mm3 , with the comment that the platelets are smaller than normal Serum immunoglobulin studies demonstrate the following: IgA 120 mg/dL IgE 2300 IU/mL IgG 900 mg/dL IgM 15 mg/dL Patients with this condition have a significantly increased incidence of which of the following?

762. A 15-year-old athlete is in your office for his annual physical examination before the start of football season. He has no complaints, has suffered no injuries, and appears to be physically fit. On his heart examination, you note a heart rate of 100 beats per minute, and a diffuse point of maximal impulse (PMI) with a prominent ventricular lift. He has a normal S1 and S2, with an S4 gallop. He has no murmur sitting, but when he stands you clearly hear a systolic ejection murmur along the lower left sternal edge and the apex. For which of the following conditions is this examination most consistent?

763. A 16-year-old girl, accompanied by her mother, is in your office for a well-adolescent visit. The mother asks about drug and alcohol abuse. You explain that the warning signs of abuse include which of the following?

764. A 6-month-old boy presents to the Emergency Department with a three-day history of cough, congestion and low grade fever. The mother states that the baby has not been feeding well and has used only two diapers over the past 24 hours. Physical examination reveals a pale infant with a temperature of 37.8 C (100.1 F), pulse of 170/min, respirations of 60/min and oxygen saturation of 88% on room air. The patient exhibits nasal flaring, subcostal and intercostal retractions. Lung examination reveals diffuse wheezing. Cardiac examination reveals a regular but tachycardic rhythm with no murmur. Central capillary refill is four seconds. The remainder of the examination is normal. Which of the following is the most appropriate initial step in management?

765. An infant in brought to the clinic for a routine healthy visit and vaccinations. She is the product of an uncomplicated pregnancy and has been meeting development mileposts. She is feeding well, and her mother reports that the baby seems to be growing well as well. On physical examination, the infant is afebrile with stable vital signs. She can lift her head to 90 degrees, her eyes follow past the midline, she laughs, regards her own hand and has slight awareness of her mother. Which of the following is the most likely age of this infant?

766. A two-day old infant develops seizures, bulging fontanel, and focal neurologic signs. His temperature is 37 C (98F), pulse is 180/min, and capillary refill is> 2 seconds. The initial work-up reveals a hemoglobin level of 12g/dl. Transfontanel ultrasonography demonstrates a hemorrhage involving the germinal matrix, lateral ventricles, and brain parenchyma. Which of the following is the most significant risk factor for this newborn's condition?

768. A 4-year-old boy was admitted to the hospital last night with the complaint of “difficulty breathing.” He has no past history of lung infection, no recent travel, and no day- care exposure; he does, however, have an annoying tendency to eat dirt. In the emergency center he was noted to be wheezing and to have hepatomegaly. He is able to talk, relaying his concern about his 6-week-old Chihuahua being left alone at home. Laboratory studies revealed marked eosinophilia (60% eosinophils). Which of the following tests is most likely to produce a specific diagnosis?

769. A 10-year-old Caucasian boy is brought to the emergency room by his mother with right hemiplegia of sudden onset. The mother says that the child fell on a pencil in his mouth, ten hours before the onset of symptoms. His past medical history is insignificant. Family history is not significant. His blood pressure 110/60 mmHg and heart rate is 90/min. Physical examination reveals dense right hemiplegia, right hemianesthesia, and mild motor aphasia. Cardiac auscultation reveals S3. What is the most probable cause of this patient's condition?

770. pregnancy, and was normal at birth. He otherwise appears healthy and is feeding well. Vital signs are stable. Physical examination shows jaundice. There is no organomegaly. Laboratory investigations show: Hemoglobin 17.0 g/L MCV 88 fl Platelets 220,000/mm3 Leukocyte count 4,500/mm3 Total bilirubin 7.5 mg/dL Indirect bilirubin 6.0 mg/dL What is the most likely cause of this patient's jaundice?

771. A 2-year-old child is admitted to your hospital team. The child's primary care doctor has been following the child for several days and has noted her to have had high fever, peeling skin, abdominal pain, and a bright red throat. You are concerned because twocommon pediatric problems that could explain this child’s condition have overlapping presenting signs and symptoms. Which of the following statements comparing these two diseases in your differential is true?

772. Two new mothers are discussing their infants outside the neonatal intensive care unit. Both were born at 36 weeks’ gestation. One infant weighs 2600 g (5 lb, 12 oz) while the other infant weighs 1600 g (3 lb, 8 oz). The mother of the second infant should be told that her child is more likely to have which of the following conditions?

773. A 6-month-old male is brought to the office due to fussiness and tugging at his right ear for the past 2 days. He has had a fever of 39.4 C (103 F) for the past 2 days. His past medical history is significant for recurrent ear and lung infections, oral candidiasis, and persistent diarrhea by rotavirus. His temperature is 39.4 C (103F), pulse rate is 150/min, respirations are 28/min, and blood pressure is 80/60mm Hg. Physical examination reveals an erythematous, bulging right tympanic membrane with poor mobility on pneumatic otoscopy. His lymph nodes are not palpable, and his tonsils are not visualized. His B and T lymphocyte levels are markedly reduced. The chest x-ray reveals an absent thymic shadow. What is the most likely etiology of this patient's condition?

774. A school teacher calls you to report that his 7-year-old student had about 10 episodes of eye blinking and gabbing today, which lasted approximately 30 seconds each. The child sat in his chair and did not have any postictal confusion. The teacher noticed several similar episodes during the last month, as well as a decline in the child's school performance. What type of seizure does this child have?

775. A 10-year-old girl has had a " cold" for 14 days. In the 2 days prior to the visit to your office, she has developed a fever of 39degree celcus, purulent nasal discharge, facial pain, and a daytime cough. Examination of the nose after topical decongestants shows pus in the middle meatus. Which of the following is the most likely diagnosis?

776. A 16-year-old girl is being evaluated for primary amenorrhea. Her birth history is significant for low birth weight and bilateral swelling of the hands and feet. Her blood pressure is 170/96 mmHg. She has a short stature and webbed neck. Her karyotype examination results show 22 pairs of autosomes, one X, and one Y chromosome. Which of the following statements is true regarding this patient's condition?

777. An 8-year-old girl presents with well-controlled, moderately persistent asthma.Her therapies consist of occasional use of short-acting β-agonists, daily inhaled steroids, and a leukotriene inhibitor. She presents with white patches on her buccal mucosa. You recommend which of the following?

778. A 4-year-old boy, who has a ventriculoperitoneal shunt for congenital hydrocephalus, develops fever, headache, irritability, lethargy, photophobia, and vomiting. His temperature is 39.6 C (103.2 F). He is noted to have nuchal rigidity, with the presence of both Kernig's and Brudzinski's signs. The shunt tract is erythematous on the surface. A lumbar puncture is performed and shows a WBC of 40,000/mm3 with 85% neutrophils, a glucose concentration of 48 mg/dL, and a protein concentration of 169 mg/dL. Which of the following is the most likely pathogen?

779. A 16-year-old boy presents with a temperature of 38.4 C (101 F) and low back, wrist, and knee pain. He had a sore throat 1 month earlier. His arthritis is diffuse. Pea-sized swellings are noted over the skin on his knees. He has a serpiginous erythematous area on his anterior trunk. His blood and throat cultures are negative, and his CBC is unremarkable. His antistreptolysin-O (ASO) titer is high. Which of the following is the most appropriate therapy?

780. A 2-year-old child is brought by an anxious mother to the emergency department because of difficulty in breathing for the past 12 hours. The child has a history of runny nose that started 3 days ago. He suddenly developed a progressively increasing difficulty in breathing. The mother reports that the child "sounds like a barking dog when he coughs." The child's temperature is 37.7C (99.9F), respirations are 30/min, blood pressure is 90/60mm Hg, and pulse rate is 104/min. He is coughing and using his accessory muscles of respiration. His oxygen saturation is 98% on 2L of oxygen. He is diagnosed with laryngotracheobronchitits, started on humidified oxygen, and kept in an upright position. After 20 minutes, he becomes An 8-year-old girl presents with well-controlled, moderately persistent asthma. Her more irritable, his oxygen saturation drops to 92%, respirations increase to 40/min, and pulse increases to 120/min. His blood pressure and temperature are unchanged. What is the most appropriate next step in the management of this patient?

781. A 5-year-old boy is brought to the clinic by his mother because he was sent home by the school nurse. The nurse claims to have heard a murmur in his chest. The child has always been healthy, and has never had any shortness of breath, chest pain, dizziness or any other illnesses. On examination, the child appears alert, and his vital signs are stable. Auscultation of the chest reveals a grade-2 systolic ejection murmur at the left sternal border, but no other extra sounds. The murmur changes with position. What is the best next step in the management of this patient?

785. A 7 -year-old girl is brought to the physician's office by her mother due to recurrent, prolonged episodes of nausea and severe vomiting for the past 4 days. According to the mother, the vomiting starts in the early morning and recur 7 to 8 times daily. The child denies any headache, abdominal pain, diarrhea, chest pain or respiratory distress. She has had two similar episodes of vomiting and nausea in the past year, which resolved spontaneously. The mother has a history of migraines. On examination, the child is afebrile and has pallor with signs of mild dehydration. The abdomen is soft and non-tender to palpation. What is the most likely cause of this child's symptoms?

786. A father brings his 18-month-old daughter to the office for the evaluation of fever for the past 1 0 days. The father, who works as a phlebotomist, says that the temperature seems higher in the morning and again at night, often reaching 40.5C (105F), and is sometimes associated with shaking chills. He remembers that the child developed severe respiratory distress and skin rash when treated with penicillin in the past. He has heard about the development of 'liver toxicities' in children treated with aspirin, and he is interested in knowing everything about his daughter's condition. On examination, the child is in no acute distress. Her temperature is 39.4C (103F), pulse rate is 90/min, and blood pressure is 1 00/60 mmHg. Her sclerae are anicteric. There is bulbar conjunctival injection, and the oropharynx shows diffuse mucosal injection with fissuring and crusting of the lips. There are numerous hyperemic macules over her entire body, and her palms appear edematous. Based on the above description, which of the following is the most accurate statement?

787. A term newborn is delivered vaginally following a breech presentation. On physical examination, the Barlow test is positive for bilateral subluxation of the hips. There is decreased abduction of both hips. Besides breech presentation, which of the following infants are most at risk for developmental dysplasia of the hip?

788. A 4-month-old infant boy has gained only 10 ounces since birth. He has failed to gain weight with multiple formula preparations. His stools have been loose and fatty. An older sister had similar symptoms and has been repeatedly hospitalized for failure to thrive and recurrent pulmonary infections. Which of the following is the most likely cause of this patient's gastrointestinal symptoms?

790. A 3-month-old, previously well male infant presents to the emergency department in January with a 2-day history of clear rhinorrhea, low-grade fever, and poor appetite, but no cough. On physical examination, there are mild subcostal retractions, coarse breath sounds heard throughout the lung fields, and scattered expiratory wheezes. The child receives an intravenous fluid bolus in the emergency department and is admitted for observation. Which of the following is the most severe, life-threatening complication of this child's illness?

791. A 14-year-old boy has pain in his left leg. An x-ray shows a tumor and a biopsy reveals histopathologic features characteristic of neural origin. Which of the following is the most likely diagnosis?

792. A 7-year-old boy arrives at the emergency room in acute distress. Over the past 3 to 4 days he has become progressively ill with generalized fatigue and mild, mid-abdominal pain that have become steadily worse. On physical examination he has a maculopapular rash on his thighs and feet with some spread of the rash to his buttocks. The rash does not blanch and the some lesions near the ankles look petechial or bruised. His temperature is 39.0 C (102.2 F) and he is drawing his knees to his chest for relief of his stomach pains. He is nauseated and vomited once before coming to the hospital. He has semi-soft dark stool, which is guaiac-positive. The boy has not voided since early morning and cannot provide a urine sample. The doctor determines that he is 10% dehydrated and asks the nurse to start intravenous fluids. Which of the following is the most likely diagnosis?

793. A newborn girl is noted to be drooling saliva, and she chokes violently when she is first fed. On physical examination, she is found to have abdominal distention and an imperforate anus. There is no fistula to the perineum or vagina. Examination of the urine reveals no meconium in it. Echocardiogram and renal sonogram are reported as negative for other congenital defects. X-ray films show abundant gas in the gastrointestinal tract. Pictures taken with a metal marker taped to the anus, and the baby hanging upside down, show that there is a significant distance (2.5 cm) between the blind end of the rectum and the anal marker. Before a diverting colostomy is performed, which of the following steps should be taken?

794. A newborn male has oliguria and a midline mass in the lower abdomen. What is the most likely diagnosis?

795. A 22-month-old boy who recently immigrated from Eastern Europe with his family is brought to your office by his mother who is worried that he seems to tire easily. She describes how he becomes short of breath with even mild physical activity and cannot keep up with his peers during play. The boy is at the 40th percentile for height and 20th percentile for weight. On general examination, there is no clubbing, cyanosis, or peripheral edema, but there is a harsh 3/6 holosystolic murmur over the left lower sternal border and a rumbling diastolic murmur over the cardiac apex. Which of the following is the most likely cause of his symptoms?

796. A 15-year-old Caucasian female comes to your office because her menses have not yet started. Her breast development is Tanner stage 2 and there is scant pubic hair. Physical examination is also significant for decreased femoral pulses. Which of the following is the best next step in evaluating her condition?

798. A 5-month-old child was normal at birth, but the family reports that the child does not seem to look at them any longer. They also report the child seems to “startle” more easily than he had before. Testing of his white blood cells (WBCs) identifies the absence of -hexosaminidase A activity, confirming the diagnosis of which of the following?

799. The family of a 4-year-old boy has just moved into your area. The child was recently brought to the emergency department (ED) for an evaluation of abdominal pain. Although appendicitis was ruled out in the ED and the child’s abdominal pain has resolved, the ED physician requested that the family follow up in your office to evaluate an incidental finding of an elevated creatine kinase. The family notes that he was a late walker (began walking independently at about 18 months of age), that he is more clumsy than their daughter was at the same age (especially when trying to hold onto small objects), and that he seems to be somewhat sluggish when he runs, climbs stairs, rises from the ground after he sits, and rides his tricycle. A thorough history and physical examination are likely to reveal which of the following?

800. A 15-month-old boy is brought into the clinic with a 1-day history of fever, decreased oral intake, and runny nose. His vital signs are within normal limits except for a temperature of 39.5 C (103.1 F). He is active and in no distress. His ears are clear bilaterally. There is a clear nasal discharge. Multiple small (1-2 mm) vesicular lesions are noted on the mucosa of the anterior tonsillar pillars and posterior palate. The rest of his examination is within normal limits. Which of the following is the most likely diagnosis?

801. A nurse notices that a 1-week-old, premature infant in the neonatal unit is experiencing migratory jerks of the extremities. She picks the infant up and can feel that the muscle jerks are continuing to happen, even when she holds an involved extremity still. After about 5 minutes, the jerking movements stop. Which of the following is the most appropriate first step in diagnosis?

802. A neonate develops severe cyanosis that begins within minutes of birth. Blood drawn one hour after birth shows metabolic acidosis with respiratory acidosis. A chest x-ray film shows a narrow base to the great vessels and the heart resembles an egg on its side. ECG is normal. Which of the following is the most likely diagnosis?

803. A 13-year-old boy is seen for right knee pain that has persisted for the past 2 months despite the use of over-the-counter analgesics. His mother states that he has been limping since he started to have the pain. The pain is of insidious onset, but its intensity sometimes suddenly increases. On physical examination, the boy is obese; his weight is higher than the 90th percentile. Flexion of the right hip causes marked outward rotation and reproduces the pain. Internal rotation of the right hip is limited, and the right leg is slightly shortened compared with the left leg. Which of the following is the most likely diagnosis?

804. A 2-week-old male infant is brought to the office by his mother due to fever and vomiting for the past two days. He appeared normal until two days ago. He is being breastfed. He was born at 32 weeks gestation and weighed 2.7kg (6 Ib) at birth. On examination, he is ill-looking, lethargic, and febrile. His abdomen is distended, bowel sounds are absent, and stool is guaiac-positive. An abdominal x-ray demonstrates pneumatosis intestinalis. What is the most likely diagnosis of this patient?

805. A 5-year-old Mexican female child is brought to the office for the evaluation of a pruritic vulva for the past fifteen days. The pruritus is felt mostly during the night. Her 4-year-old cousin who visited them four weeks ago has a similar complaint. On examination, there is no vaginal discharge, but the vulva is erythematous. The rest of the physical examination is normal. What is the most appropriate next step in the management of this patient?

807. The parents of a 5-year-old boy come to the physician concerned about their child's recurrent leg pains. The boy has been complaining for several weeks about pain in both legs, usually occurring soon after going to bed. He derives relief from rubbing his legs and knees. He does not limp and is able to participate in sports activities. Which of the following is the most likely diagnosis?

808. A young black male with sickle cell trait is preparing for his travel to West Africa from North America. While obtaining his visa, he is advised by the health inspector to obtain some immunizations, although his chances of getting a certain tropical disorder are low. What disease has the sickle cell trait been shown to convey protection against?

809. A 5-year-old boy is brought to the emergency department by his mother. One week ago, he developed a low grade fever followed by persistent bouts of coughing that last 20-30 minutes each. The coughing spells are severe, unresponsive to antitussive medications, and appear to worsen with eating and drinking cold liquids. On physical examination, there is subconjunctival hemorrhage and extensive subcutaneous emphysema over the anterior chest. What is the most likely organism responsible for this child's illness?

811. A 4-year-old boy is brought to the emergency department for a painful and swollen right forearm. He was bitten and scratched by a family cat 2 days ago in the affected area. His temperature is 39.6 C (103.2 F). The right forearm is erythematous, edematous, and tender to touch. Which of the following is the most appropriate antibiotic treatment for this patient?

812. A 6-year-old boy is brought to the office by his parents after hearing that chicken pox is infectious and can occur in unimmunized contacts. One week ago, he and his family visited relatives, and one of his cousins had chicken pox at that time. He and his two other siblings are apparently healthy, and never had any "chicken pox shots." What is the best next step in the management of this patient?

813. You are called to the nursery to evaluate a newborn infant. The mother is a 24-year-old primigravida. Her pregnancy was complicated by preeclampsia. The infant was delivered at 39-weeks’ gestation via emergent cesarean section due to maternal hypertension and non-reassuring fetal heart tones. On examination, the infant's weight is 2.6 kg (5 lb 11 oz) placing him in the 5th percentile, height is 18 inches (46 em) placing him in the 5th percentile, and head circumference is 13 inches (33 cm) placing him in the 1oth percentile. The infant's head seems large for her body. There is a paucity of subcutaneous fat. The remainder of the physical examination is unremarkable. This infant is at risk for developing which of the following?

815. A one-month-old infant is brought to the physician for evaluation. His mother reports that for the past two weeks, he has been crying inconsolably for several hours every evening. His mother has tried multiple methods to calm the infant down, but nothing seems to work. The infant was born full term without complications. He takes two ounces of cow's milk-based formula every two hours and is growing well. His mother reports that he is happy and alert the rest of the day. The child's physical examination is unremarkable. Which of the following is a true statement about the child's condition?

816. An 18-month-old male is brought to the hospital because of fever, dyspnea, and productive cough of two days duration. His mother reports that he just recovered from prolonged diarrhea due to Giardia infection. His past medical history is also significant for pneumonia and recurrent ear infections since 6 months of age. On physical examination, his temperature is 38.7°C (101.7°F), pulse is 140/min, and respirations are 40/min. Examination reveals a young child in mild respiratory distress and bronchial breath sounds in the right lower lung lobe. Which of the following is the most likely cause of his recurrent infections?

818. A previously healthy 6-year-old girl is brought to the office due to a 10-day history of persistent, thick, nasal discharge, nasal congestion, cough, and intermittent low-grade fever. She has had no vomiting, headache, earache, or rash. Her temperature is 37.2 C (98.9 F), blood pressure is 88/50 mmHg, pulse is 90/min, and respirations are 15/min. Physical examination shows clear tympanic membranes, congested posterior nasopharynx with thick, yellow and purulent mucus, and red, swollen nasal turbinates. Transillumination of the sinuses is equivocal. Palpation of the maxillary sinuses shows mild tenderness. Lungs are clearto auscultation. Which of the following organisms is the most common etiologic agent of this condition?

819. A one-week-old infant is admitted to the neonatal intensive care unit due to vomiting, abdominal distension, and poor feeding. His vomitus is bile-stained. There is frank blood in his stools. He has been formula- fed since birth. Physical examination shows diminished bowel sounds. Abdominal x-rays reveal dilated loops of bowel with intramural air Laboratory studies show elevated WBCs. What is the most likely diagnosis?

820. A 14-year-old male presents with a complaint of soreness, and weakness in his legs for the past day that has slowly spread from his calves to his thighs. He now complains of weakness in his trunk and arms. On examination he appears tired and lays on the examining table. His temperature is 37 C (98.6 F), pulse is 48/min, and respirations are 22/min. Both of his legs are diffusely tender. Deep tendon reflexes are absent in the lower extremities, and sensation is greatly diminished. Which of the following studies is essential for this patient's diagnosis?

821. A 14-year-old boy is hit by an automobile while walking across the street and is immediately taken to the emergency department. On arrival, he is conscious and complains of shortness of breath and chest pain. Physical examination reveals an ecchymotic area over his right chest and subcutaneous emphysema. Breath sounds are absent on the right side. His trachea is deviated to the left, and his right hemithorax is tympanic to percussion. Which of the following is the most appropriate initial step in management of this patient?

822. A child has a 2-week history of spiking fevers, which have been as high as 40°C (104°F). She has spindle-shaped swelling of finger joints and complains of upper sternal pain. When she has fever, the parents note a faint salmon-colored rash that resolves with the resolution of the fever. She has had no conjunctivitis or mucositis, but her heart sounds are muffled and she has increased pulsus paradoxus. Which of the following is the most likely diagnosis?

823. In the newborn nursery it is noted that a child has uneven gluteal folds. Physical examination of the child's hips reveals that one of them can be easily dislocated posteriorly with a jerk and a "click," and returned to normal position with a "snapping" sound. The family is concerned because a previous child had the same problem. Which of the following is the most likely diagnosis?

824. A 3-year-old boy is brought to the emergency department because of a worsening cough over the past week. His temperature is 38.9 C (102 F), and inspiratory stridor is noted. A plain film of the neck reveals subglottic swelling. He is noted to have copious thick secretions and a barking cough. He has not had such events previously, and his parents deny recent contact with sick children. The patient is in respiratory distress and is noted to be retracting his subcostal muscles to breathe. Which of the following is the next most appropriate step in management?

825. A cyanotic newborn is suspected of having congenital heart disease. He has an increased left ventricular impulse and a holosystolic murmur along the left sternal border. The ECG shows left-axis deviation and left ventricular hypertrophy (LVH). Which of the following is the most likely diagnosis?

826. A 3-day-old infant with a single second heart sound has had progressively deepening cyanosis since birth but no respiratory distress. Chest radiography demonstrates no cardiomegaly and normal pulmonary vasculature. An ECG shows an axis of 120°and right ventricular prominence. Which of the following congenital cardiac malformations is most likely responsible for the cyanosis?

827. A 14-year-old girl is brought to the office by her mother for the evaluation of leg muscle fatigability while climbing the stairs. She has occasional headaches. She was diagnosed (via karyotyping) with Turner's syndrome two years ago. Her blood pressure is 165/95 mm Hg on the right arm, and 161/95 mm Hg on the left arm. Her heart rate is 85/min. The physical examination reveals no secondary sexual characteristics. Her chest is broad. The point of maximal apical impulse is displaced to the left and increased in intensity. A mild, continuous murmur is heard all over the chest. The lungs are clear. What is the most probable finding on her chest radiograph?

828. A 2-year-old child is brought to the office due to vomiting. He is recovering from an upper respiratory infection, which was treated by his mother with over-the-counter aspirin. On examination he is irritable, lethargic, agitated and uncooperative. His height, weight and head circumference are at the 50th percentile. The pupils are equal and have a sluggish reaction to light. The sclera is non-icteric. The neck is supple and without adenopathy. The abdomen is flat, with normal bowel sounds. The lab findings are as follows: Serum bilirubin Normal Serum ASAT and ALAT Increased Serum ammonia Increased Prothrombin time Prolonged A CT scan of the brain shows cerebral edema. CSF analysis is normal, except for increased pressure. What is the most likely diagnosis?

829. A 6-year-old child, attempting to pet a neighbor's domestic dog while the dog is eating, is bitten in the hand. The dog has been vaccinated regularly. Which of the following steps are needed for rabies prophylaxis in this case?

830. A 1-month-old baby boy has bloody diarrhea. No infectious agent is identified, but the baby is found to be profoundly thrombocytopenic. The baby is also noted to have a skin rash, and a dermatologist diagnoses eczema. By three months of age, the baby begins to develop recurrent respiratory infections. If this child survives until adolescence, he is at particularly high risk of developing which of the following?

831. An ill-appearing 2-week-old baby girl is brought to the emergency room. She is pale and dyspneic with a respiratory rate of 80 breaths per minute. Heart rate is 195 beats per minute, heart sounds are distant, a gallop is heard, and she has cardiomegaly on x-ray. An echocardiogram demonstrates poor ventricular function, dilated ventricles, and dilation of the left atrium. An ECG shows ventricular depolarization complexes that have low voltage. Which of the following is the most likely diagnosis based on this clinical picture?

832. A frantic mother telephones the pediatric office. She reports that her 10-year-old boy accidentally splashed Drano (a strongly corrosive, alkaline drain cleaner) on his face, and he is screaming in pain complaining that his right eye hurts terribly. Which of the following is the best advice to give to the mother?

833. The mother of a 4-year-old child takes her daughter to a pediatrician because she is "scratching all the time." Physical examination demonstrates multiple areas of excoriation, which are worst on the shoulders, buttocks, and abdomen. In the areas where the scratching has occurred, scattered tiny red punctate lesions are also seen. Careful examination of the clothing reveals small, ovoid, grayish-white structures attached to threads on the seams. Which of the following is the most likely causative agent?

834. A newborn infant has mild cyanosis, diaphoresis, poor peripheral pulses, hepatomegaly, and cardiomegaly. Respiratory rate is 60 breaths per minute, and heart rate is 250 beats per minute. The child most likely has congestive heart failure caused by which of the following?

836. A healthy 7 -year-old Caucasian boy is brought to the office by his mother because of fever and pain in the ear. He has had these symptoms for the past three days. He has no other medical problems. Family history is not significant. He takes no medication. His temperature is 38.3 C (101 F). Otoscopic examination reveals an ear discharge, and the tympanic membrane is immobile with insufflation. He has a boil just behind the pinna of the involved ear. His WBC count is 12,000/mm3. He is diagnosed with otitis media. Which of the following is most specific for the diagnosis of otitis media?

837. You are called to examine a newly delivered infant, who is 41 weeks gestation and a product of an uncomplicated pregnancy. Physical examination reveals a matted mass of edematous bowel loops protruding from the abdomen. There is no covering over the bowel loops. The umbilical cord appears normal. Which of the following is the best next step in the management of this patient?

838. A 3 year old male has sudden onset of dry cough with a small amount of bright red blood produced when he coughs. He has had no fevers, runny nose, or vomiting. In the Emergency Department a chest x-ray shows hyperexpansion of the right lung and clear lung fields. Which of the following is the most likely etiology of this child's symptoms?

839. A 17-year-old girl is found unconscious in a bathroom after ingesting a large amount of unknown sleeping pills. On arriving at the emergency department, she is somnolent; her temperature is 37.2 C (98.9 F), blood pressure is 120/74 mm Hg, pulse is 68/min, and respirations are 12/min. She responds to painful stimuli and to hearing her name loudly by opening her eyes briefly. However, she returns to the somnolent state immediately afterward. Which of the following is the most appropriate initial intervention?

840. A female neonate is undergoing an examination after birth. She was born to a 33-year-old primigravid mother at term via a normal spontaneous vaginal delivery. The pregnancy was uncomplicated, except for a positive maternal group B Streptococcus culture at 36 weeks' gestation, for which the mother received penicillin during labor. The infant's APGAR scores are 8 at 1 minute and 9 at 5 minutes. The mother notices that the infant has prominent labia and a dull pink vaginal epithelium. Which of the following is the most likely cause of the appearance of the infant's genitalia?

841. A 2-year-old boy presents to the emergency department with fever, irritability, and a skin rash 5 days after the onset of an upper respiratory infection. On examination, his temperature is 39.8 C (103.6 F), and his pulse is 94/min. There is an erythematous skin rash that involves his face, chest, back, and upper extremities. His skin is very tender to touch. Rubbing the skin causes separation of the epidermal layer. Which of the following is the most likely diagnosis?

842. A 9-year-old girl is brought by her sister to her pediatrician with the complaint of severe, intermittent headaches for the past several months, one of which resulted in her going to the ER. The physical examination today, including a careful neurologic examination, is normal. The headache is diffuse, throbbing, lasts several hours, and is not associated with vomiting or other symptoms. The child cannot feel the headaches coming on; they appear on all days of the week; and usually the headaches are gone when she awakens from a nap. The child reports that she is doing well in school, plays clarinet in the school band, and has “lots of friends.” The sister is not sure, but she thinks their father, who lives in another state, may have headaches. The most likely explanation for this girl’s headache is which of the following?

843. Examination of the cerebrospinal fluid (CSF) of an 8-year-old, mildly febrile child with nuchal rigidity and intermittent stupor shows the following: WBCs 85/L (all lymphocytes), negative Gram stain, protein 150 mg/dL, and glucose 15 mg/dL. A computed tomographic (CT) scan with contrast shows enhancement of the basal cisterns by the contrast material. Which of the following is the most likely diagnosis?

845. A full term neonate is being evaluated following an uncomplicated pregnancy and delivery on day 1 of life. He weighs 3.6kg (8ib), is 20in (50.8cm) tall, and has a head circumference of 13.5in (34cm). His physical examination is unremarkable. Initial laboratory data is shown below. Complete blood count Hemoglobin 20g/L Hematocrit 73% Platelets 200,000/mm3 Leukocyte count 5,500/mm3 Neutrophils 56% Eosinophils 1% Lymphocytes 33% Monocytes 10% Which of the following findings is most likely to be detected in this neonate?

846. The mother of a 2-year-old male child states that she has noticed white, cheeselike material arising from his foreskin and also that he cannot fully retract the foreskin behind the glans penis. Which of the following is the correct advice for this parent?

847. An 8-year-old boy is brought to the emergency department with a head injury. He hit his head on the ground when he fell off his bicycle. He was not wearing a helmet at the time. There was no loss of consciousness. He vomited 2 times after the accident and now complains of a right-sided headache and inability to hear with his right ear. There is no photophobia or diplopia. On physical examination, his blood pressure is 110/72 mm Hg, pulse is 104/min, and respirations are 22/min. He is alert and oriented and responds appropriately to questions. There is a round hematoma on the right side of his head. Bloody drainage is noted from his right ear. Which of the following injury is most consistent with these findings?

848. A 16-year-old girl comes to the physician's office because she has not begun menstruating yet. Both her mother and an older sister started menstruation at age 12. She takes no medication and denies strenuous exercise or excessive dieting. Her height is at the 50fh percentile for age; her weight is at the 60fh percentile. Both her breast and pubic hair development are at Tanner stage 4. Pelvic ultrasonography reveals a normal uterus and ovaries. Which of the following is the most likely diagnosis?

849. A one-month-old infant is born with craniofacial anomalies. Further evaluation reveals a cognitive impairment, a 22q 11 microdeletion in his chromosomes, and a heart condition with a right-to-left shunt. The infant subsequently undergoes heart surgery. The surgeon notes that the patient's thymus is absent. The anesthesiologist observes prolonged QT intervals in the patient's ECG. What is the most important parameter that should be monitored throughout this surgery?

850. An 8-month-old male infant is brought to the emergency department (ED) by his mother due to vomiting and a decreased urine output. Three days ago, he had a fever, sore throat and ear pain. He was subsequently diagnosed with otitis media and treated with oral amoxicillin. Today, in the ED, his temperature is 40.0C(104F), pulse is 80/min, respirations are 40/min and irregular, blood pressure is 100/60 mm Hg, and weight is 8kgs ( 15 lbs). He is lethargic and arousable only to painful stimuli. His anterior fontanel is full and tense. His tympanic membranes are red and bulging. His pupils are reactive, but his eyes do not focus well on his parents What is the most appropriate next step in the management of this patient?

851. A 12-year-old boy presents with a 2-month history of recurrent headache and deteriorating school performance. Neurologic examination is unremarkable except for bitemporal deficits in his visual field. X-ray and MRI of the head are performed. X-ray films show calcifications in the suprasellar region, while MRI images reveal a multicystic tumor displacing the optic chiasm. The patient undergoes neurosurgical operation for excision of the tumor. During the procedure, the surgeon notices that the cystic cavities contain a "machinery oil"-like fluid. Which of the following is the most likely diagnosis?

852. A 5-year-old female child is brought to the emergency department due to fever, chills and abdominal pain. She has been complaining of burning micturition and abdominal pain for the last 2 days. Her temperature is 102 F (38.9C), respirations are 20/min, pulse is 130/min, and blood pressure is 90/60 mmHg. Physical examination reveals costovertebral angle tenderness. Urine analysis shows pyuria, significant bacteriuria, WBC casts, positive nitrite, and esterase. What is the most likely cause of this condition in children?

853. A 10-year-old girl is brought to the office for a follow-up visit. She has been previously diagnosed with vesicoureteral reflux, and has had multiple episodes of acute urinary tract infections in the past. Intravenous pyelography (performed on her last visit) reveals bilateral focal parenchymal scarring and blunted calyces. What is the most likely diagnosis?

854. An 8-year-old immigrant from rural Central America presents with complaints of weakness, facial swelling, muscle pain, and fever. A CBC reveals marked eosinophilia. Which of the following parasites is most likely to be responsible?

855. A patient presents to the emergency center with a 6-hour history of fever to 38.9C (102F). Her mother reports that the patient appeared to be feeling poorly, that she had been eating less than normal, and that she vomited once. About 2 hours prior to arrival at the ER, the mother states that she noted a few purple spots scattered about the body on the patient, especially on the buttocks and legs. On the 30-minute ride to the ER, the purple areas spread rapidly and became coalesced in areas, and the patient is now obtunded. Which of the following is the most likely diagnosis?

856. A 3-year-old African-American female is brought to the office due to a swelling in her abdomen. According to her parents, this swelling was first noted when she was 3 months old, and has been increasing in size over the past 6 months. It is more pronounced during crying and coughing. Examination reveals a soft swelling of the umbilical region that is 3 cm in diameter and covered by skin. It can be easily reduced through the fibrous ring at the umbilicus. The child is afebrile and in good health. What is the most likely diagnosis and best course of action for this patient?

857. A 6-year-old boy is brought to the office due to a sudden onset of petechiae and epistaxis. Three weeks ago, he had an upper respiratory tract infection which resolved uneventfully. Physical examination shows a few petechiae over the trunk and extremities, but is otherwise unremarkable. Laboratory studies show: Hb 13.5g/dL WBC 7, 000/mm3 Differential count normal Platelets 60, 000/mm3 What is the most appropriate next step in the management of this patient?

858. A 6-year-old boy is brought to the pediatrician because of a 3-day history of skin lesions. On physical examination, he has multiple yellow, crusted erosions below the nares and on the cheeks, chin, and upper extremities. The rest of the examination is normal. Which of the following is the most appropriate treatment for this condition?

859. A 10-year-old girl comes to medical attention because of recurrent attacks of wheezing and dyspnea. The attacks occur mostly at home or, if outdoors, soon after exercise. Exacerbations are noted in springtime. The severity of symptoms is mild- Pulmonary function tests show that peak expiratory flow (PEF) and forced respiratory volume per second (FEVj) are reduced during an attack but are relatively normal during symptom-free intervals. Height and weight are in the 60th percentile. Complete blood count shows 8% eosinophils; all other parameters are normal. Cutaneous testing shows the patient to be allergic to a variety of allergens, including dust mites, animal dander, and several pollens. Which of the following is the most effective step in management?

860. A term neonate appears healthy at birth and receives routine perinatal care. Ten days after delivery, the infant develops severe eyelid edema with copious drainage of mucopurulent material and pseudomembrane formation. Which of the following is the most likely diagnosis?

861. A 5-year-old girl without past history of UTI is in the hospital on antibiotics for Escherichia coli pyelonephritis. She is still febrile after 4 days of appropriate antibiotics. A renal ultrasound revealed no abscess, but a focal enlargement of one of the lobes of the right kidney. CT of the abdomen reveals a wedge shaped area in the right kidney distinct from the normal tissue with minimal contrast enhancement. Appropriate management of this patient includes which of the following interventions?

862. A 4-year-old boy presents with severe pains in both of his legs. On physical examination, his temperature is 37.7 C (99.8 F), blood pressure is 108/68 mm Hg, pulse is 96/min, and respirations are 17/min. He is noted to have marked pallor on his lips and palpebral conjunctiva. Numerous purpura and petechiae are noted on his skin. His spleen is palpable 3 cm below his left costal margin. Laboratory evaluation reveals a white blood cell count of 1600/mm3; hemoglobin, 6.1 g/dL; and platelets, 36,000/mm3. Which of the following diagnoses is most consistent with these findings?

863. A 13-year-old healthy boy presents to the physician for a routine health maintenance visit. A urinalysis reveals 1+ proteinuria. There is no hematuria or bacteruria. His physical examination is unremarkable, revealing no edema and a normal blood pressure. Which of the following is the most likely diagnosis?

864. A 2-year-old child is brought to the emergency department because of generalized convulsions that last 15 minutes. He has had a fever for 24 hours, and his current temperature is 39.5 C (103 F). He also has a sore throat, but otherwise looks healthy. His father also had several episodes of febrile seizures in his childhood. Which of the following is the most important factor that will increase the risk of recurrence of febrile seizures?

865. A concerned mother brings her 2-month-old daughter to the clinic because of constipation. The mother had appropriate prenatal care but decided to deliver her child at home with the help of a midwife. The child has not received any medical attention since birth. Examination reveals jaundice, an umbilical hernia, and poor muscle tone. Which of the following is the most appropriate diagnostic study?

866. You have just given a 10-year-old boy an injection of pollen extract as prescribed by his allergist. You are about to move on to the next patient when the boy starts to complain about nausea and a funny feeling in his chest. You note that his face is flushed and his voice sounds muffled and strained. Which of the following is the first priority in managing this episode of anaphylaxis?

867. A previously healthy 18-month-old has been in a separate room from his family. The family notices the sudden onset of coughing, which resolves in a few minutes. Subsequently, the patient appears to be normal except for increased amounts of drooling and refusal to take foods orally. Which of the following is the most likely explanation for this toddler’s condition?

868. A term newborn infant from an uncomplicated pregnancy is being examined. He is pink, except for his extremities, which are blue. His heart rate is 150/min, and his respirations are irregular and slow at 40/min. He coughs on nasal stimulation and has some flexion of the extremities. What is his Apgar score?

869. A 2-month-old infant is brought to the clinic for the evaluation of poor feeding. He was born at 32 weeks of gestation with a birth weight of 1200 g. The pertinent physical findings are pallor, tachypnea, tachycardia, and flow murmurs. The laboratory studies are as follows: Hb 7 g/dl WBC 7,000/mm3 Platelets 230,000/mm3 Reticulocytes Low The peripheral smear shows normocytic normochromic RBC. What is the most likely diagnosis?

870. A 5-year-old girl presents with a 3-day history of fever, dyspnea, and intermittent joint pain. She has a history of sore throat about 1 month ago. On physical examination, her temperature is 39.6 C (103.2 F), blood pressure is 94/60 mm Hg, pulse is 114/min, and respirations are 22/min. Her knees and elbow joints are swollen and tender to palpation. There is a grade III/VI diastolic murmur best heard at the apex. Multiple fine, pink macules are noted on her trunk. These macules are blanching in the middle. Which of the following is the most likely diagnosis?

871. An 8-year-old boy presents to the physician for a routine health maintenance visit. His mother states that he has had difficulty reading and concentrating in his second-grade class. On examination, seven café-au-lait spots on his body, as well as two small, soft masses above his orbit, are seen. He also has axillary freckling. His mother also has café-au-lait spots on her arms. Which of the following is the most likely diagnosis?

872. A 7-month-old boy is brought to his physician because of increased agitation and restlessness. Lung examination reveals crackles and decreased breath sounds bilaterally. Chest x-ray films are notable for bilateral pneumonia. Arterial blood gas analysis reveals an oxygen tension of 45 mm Hg and a carbon dioxide tension of 60 mm Hg. Which of the following is the most appropriate next step in management?

873. A 4-year-old boy from India presents with weakness. His parents note that he has been looking increasingly pale. Hemoglobin electrophoresis demonstrates an abnormal hemoglobin species. Genetic analysis indicates that the patient has the substitution of a valine for a glutamine in the sixth position of the betahemoglobin chain. Which of the following will most likely be seen on his blood smear?

875. A 6-month-old infant has been exclusively fed a commercially available infant formula. Upon introduction of fruit juices, however, the child develops jaundice, hepatomegaly, vomiting, lethargy, irritability, and seizures. Tests for urine-reducing substances are positive. Which of the following is likely to explain this child’s condition?

876. A one-year-old girl is brought to the emergency department (ED) by her mother due to a one-day history of fever and drowsiness. The child has been irritable since yesterday. On examination, she is hypothermic, lethargic and has nuchal rigidity. She flexes her hips when her neck is flexed. She appears septic, and large petechial and purpuric lesions are developing on her body. In the ED, she suddenly becomes hypotensive. Despite aggressive fluid and antibiotic resuscitation, the child dies. What will most likely be revealed as the cause of death during the autopsy of this child?

877. A mother brings her infant into the clinic for a routine visit. Examination reveals nothing abnormal. Developmental assessment shows that the infant sits well unsupported, enjoys looking around, babbles, and has a raking grasp. What is the most likely age of this infant?

878. A 1 1/2 -year-old girl is sent to a children's hospital for evaluation following a nosebleed which was so severe as to require nasal packing and transfusion of platelet concentrates. When a blood sample had been drawn in the emergency room for serum chemistry studies, the local hospital laboratory had noted that the clot that formed was unusual in that it failed to retract. Peripheral blood smear obtained by finger puncture showed an appropriate number of normal-sized platelets, all of which were individual, without clumping. At the children's hospital, it was noted that the child's parents were cousins. Special platelet studies showed that the child's platelet's failed to aggregate with any physiologic aggregating agent, including a high concentration of exogenous ADP. Which of the following is the most likely diagnosis?

880. A 4-year-old boy and his family have recently visited a local amusement park. Several of the family members developed “gastroenteritis” with fever and diarrhea, but the 4-year-old’s stool was slightly different, as it contained blood. His mother reports that in the past 24 hours he developed pallor and lethargy; she relates that his face looks swollen and that he has been urinating very little. Laboratory evaluation reveals a hematocrit of 28% and a platelet count of 72,000/L. He has blood and protein in the urine. Which of the following diagnoses is most likely to explain these symptoms?

881. A 12-year-old boy comes to the emergency department with severe shortness of breath, cough, and fever. He was diagnosed with cystic fibrosis when he was five years old. He is currently not taking any medications. His temperature is 39.4 C (103F), blood pressure is 80/40 mmHg, pulse is 120/min, and respirations are 30/min. He is excessively using his accessory respiratory muscles. Lung auscultation reveals bilateral lower lobe crackles and expiratory wheezing. Pulse oximetry shows Sa02 of 85% that improves to 92% after oxygen supplementation. Which of the following antibiotics or combinations is the best choice for this patient?

882. A 4-day old pre term male neonate is being managed in the neonatal intensive care unit. He was born in the 34th week of gestation via lower segment caesarian section. On the first day of life, he developed tachypnea, grunting and nasal flaring. Chest x-rays showed a ground glass appearance of both lungs. He underwent endotracheal intubation and therapy with intravenous fluids, positive pressure ventilation, and intravenous antibiotics. He consequently showed remarkable improvement; however, he is currently beginning to have increased gastric residues. What is the most likely cause for this child's increased gastric residues?

883. A 14-month-old infant suddenly develops a fever of 40.2C (104.4F). Physical examination shows an alert, active infant who drinks milk eagerly. No physical abnormalities are noted. The WBC count is 22,000/L with 78% polymorphonuclear leukocytes, 18% of which are band forms. Which of the following is the most likely diagnosis?

884. A 21-year-old woman has just delivered a term infant. She has had only one visit to her obstetrician, and that was at about 6 weeks of pregnancy. She provides her laboratory results from that visit. The delivered infant is microcephalic, has cataracts, a heart murmur, and hepatosplenomegaly. Your further evaluation of the child demonstrates thrombocytopenia, mild hemolytic anemia, and, on the echocardiogram, patent ductus arteriosus and peripheral pulmonary artery stenosis. Which of the following maternal laboratory tests done at 6 weeks gestation is likely to explain the findings in this child?

885. The parents of a 7-day-old infant bring her to your office for a swollen eye. Her temperature has been normal, but for the last 2 days she has had progressive erythema and swelling over the medial aspect of the right lowe lid near the punctum. Her sclera and conjunctiva are clear. Gentle pressure extrudes a whitish material from the punctum. Which of the following ophthalmic conditions is the correct diagnosis?

886. A 3-year-old boy is brought to the office by his 27-year-old white mother for the evaluation of recurrent bone fractures. His first fracture was that of the femur, and occured when he was 6 months old. He had a fracture of the wrist 4 months ago. His mother also has a history of multiple fractures since childhood. She lost all her teeth at a very early age and is complaining of deafness. Her husband has a history of severe alcohol abuse. On examination, both mother and son have blue sclerae. What is the most likely involved disease process?

887. A 5-year-old African-American boy is brought to the office by his mother due to a painful right knee, fever and chills over the last 2 days. The child was diagnosed with pharyngitis 2 weeks ago, and was treated with a 10-day course of penicillin G. His temperature is 38.8 C (102F) and pulse rate is 102/min. On examination, his right knee joint is swollen and erythematous, with a decreased range of motion. The laboratory findings are significant for leukocytosis and an elevated ESR. X-rays of both the right hip and knee joints are normal. What is the most appropriate treatment for the patient's condition?

888. A 14-year-old girl awakens with a mild sore throat, low-grade fever, and a diffuse maculopapular rash. During the next 24 hours, she develops tender swelling of her wrists and redness of her eyes. In addition, her physician notes mild tenderness and marked swelling of her posterior cervical and occipital lymph nodes. Four days after the onset of her illness, the rash has vanished. Which of the following is the most likely diagnosis?

889. A 4-year-old child presents in the clinic with an illness notable for swelling in front of and in back of the ear on the affected side, as well as altered taste sensation. Correct statements about this condition include which of the following?

890. A 5-day-old male term neonate has been passing maroon-colored stools for the past three days, along with frequent episodes of vomiting. He is being breastfed by his mother, who is an asthmatic. His vital signs are within normal limits. The physical examination is unremarkable. Stool examination is positive for RBCs and eosinophils. What is the most likely cause of this patient's findings?

891. A 6-year-old girl is brought to the office due to significant steatorrhea and failure to thrive. She has a poor appetite and general malaise. Her past medical history is significant for prolonged neonatal jaundice and numerous respiratory tract infections. On examination, she looks a little underweight and has a runny nose. Auscultation reveals mild wheezing and diminished air entry in both lungs. Clubbing is visible on both hands. What is the best diagnostic test for this patient?

892. A 6-year-old girl is brought to the emergency room because her urine is red. She has been healthy her whole life, and has recently returned from an outing with her grandmother to a local amusement park. Her urine dip for heme is positive, suggesting which of the following is a possibility?

893. A 14-year-old girl with a history of seizures is admitted to the hospital with the diagnosis of status epilepticus. Her valproic acid level is in the therapeutic range. You arrange a 24-hour video electroencephalogram (EEG). During the EEG, she has several episodes of tonic and clonic movements with moaning and crying, with no loss of bowel or bladder control. The neurologist tells you that during the events the EEG had excessive muscle artifact but no epileptiform discharges. Which of the following treatments is the most appropriate for this condition?

894. A 6-year-old boy with mental retardation has recently been diagnosed with Fragile X syndrome. His 9-year-old sister appears to be of normal intelligence but has symptoms of attention deficit hyperactivity disorder (ADHD). What is the first test that is indicated in her work-up for ADHD?

895. A new mother complains that her 6-week-old infant frequently regurgitates small volumes of formula during and after feedings. Physical examination demonstrates a happy baby who has gained half a pound since his last visit. No abdominal masses are noted. Which of the following is the best next step in management?

896. A 3-year-old girl presents to the pediatrician's office. The mother states that the girl has been having big, bulky stools that float in the toilet. She also has intermittent diarrhea. On examination, her height is 88 cm (34.6 in, <5th percentile) and weight is 15.8 kg (34.8 lb, <5th percentile). In addition, she has an uncle who died of recurrent lower respiratory infections. Which of the following would be most effective for alleviating the gastrointestinal symptoms of this patient?

897. The signs and symptoms of meningitis in an infant can be different than those in an adult. Which of the following signs and symptoms of meningitis is more helpful in an adult patient than in a 4-month-old?

898. A woman gives birth to twins at 38 weeks’ gestation. The first twin weighs 2800 g (6 lb, 3 oz) and has a hematocrit of 70%; the second twin weighs 2100 g (4 lb, 10 oz) and has a hematocrit of 40%. Which of the following statements is correct?

899. A 9-month-old African American boy is brought to the office by his parents due to swelling of the feet and hands for the past two days, accompanied by poor feeding and fussiness. His vital signs are stable, except for a temperature of 38.3C (101 F). He appears pale. On examination, the dorsal surface of his hands and feet on both sides are swollen and tender, with restricted range of movement. He is an adopted child, and his family history is not available. Radiography of the feet and hands reveal soft tissue swelling. What is the pathophysiology of this patient's presentation?

900. A 3-year-old girl is brought to the physician's office for a routine physical examination. Her facial appearance, short stature, short webbed neck and widely spaced nipples are suggestive of a chromosomal abnormality, which is subsequently confirmed by karyotyping. What is the cardiovascular anomaly that is most likely to be present in this child?

901. A 20-year-old female is brought to the Emergency Room by her college roommate who states that the patient vomited all night. The patient complains of a sore throat and says she has not eaten for the last two days. She admits to a "sugar problem" and quit taking her medication because she has not been eating. Examination reveals an ill-appearing woman. Her temperature is 37.9 C (100.2 F), blood pressure is 118/78 mm Hg, pulse is 160/min, and respirations are 30/min. The patient's lips and mucous membranes are dry. There is a fruity odor noted to the patient's breath. The lung and cardiac examination are unremarkable except for mild tachypnea and tachycardia. Laboratory analysis shows: Sodium......................130 mEq/L Potassium..................6.1 mEq/L Chloride....................100 mEq/L Bicarbonate...............8 mEq/L Urea nitrogen............10 mg/dL Creatinine.................1.0 mg/dL Glucose....................680 mg/dL pH...........................7.15 pCO2.......................30 mm Hg pO2.........................85 mm Hg Urinalysis is positive for ketones. Which of the following is the most appropriate initial step in management?

902. An 8-year-old boy is seen in the pediatrician's office for a routine health supervision visit. The mother states that he has Duchenne muscular dystrophy. On examination, he is found to have hip waddle and enlargement of both calves. He is ambulatory, but his muscle strength is diminished symmetrically. Which of the following signs is most consistent with Duchenne muscular dystrophy?

903. A 7-year-old girl was found in a routine health supervision visit to have bilateral breast tissue development. She also had long, pigmented hair over the labia majora. Her height and weight are both at the 80th percentile for her age. Which of the following is the most appropriate management?

904. An 8-year-old boy is brought to the pediatrician with a rash on his abdomen. The mother first noticed the rash about 3 weeks ago. The boy has no fever or other symptoms. On examination, there is a well-circumscribed, circular, erythematous, scaly annular patch on his abdomen. The border of the skin lesion is raised and well defined. Which of the following is the most likely diagnosis?

905. A 16-year-old arrives to your office soon after beginning basketball season. He states that he has had progressive pain in his knees. A physical examination reveals, in addition to tenderness, a swollen and prominent tibial tubercle. Radiographs of the area are unremarkable. Which of the following is the most likely diagnosis?

907. A 4-year-old boy is brought to the office for a routine exam. He has a small face, upslanting palpebral fissures, a speckled iris, and a simian crease. Auscultation reveals a loud P2. His mother informs you that he has trisomy. What is the most likely congenital heart disorder in this patient?

908. A mother brings her 4-year-old son to see you. She seems to be very concerned about her child's bedwetting. As you explore the history, the mother tells you that she started his toilet training when he was 2 years old. The child responded to his mother's efforts and slowly was able to reduce the frequency of bedwetting. However, he did not completely succeed and still occasionally wets his bed. She has become so concerned that she demands you to order tests and prescribe some drugs to resolve the problem. What is your best next step in the management of this boy?

909. An infant comes to the office for his 1-year check up. His father states that he is worried that his son is smaller than he should be. The child's weight is 8.6 kg (19 lb), and his length is 71 cm (28 in). He appears to be growing appropriately on his growth curve. Which of the following is the most appropriate explanation about growth to be given to the father?

910. A 15-year-old Ashkenazi Jewish boy comes to the office because of pain in his right knee. He gives a history of easy bruising and chronic fatigue. His height and weight are in the 40th percentile mark for his age. The physical examination reveals tenderness over the lower end of the right femur, mildly enlarged liver, and moderately enlarged spleen. X-rays of the right femur reveal an Erlenmeyer flask deformity of the distal femur. Significant lab findings are anemia and thrombocytopenia. A bone marrow examination reveals cells with a wrinkled paper appearance. What is the most likely cause of this patient's condition?

911. A 7-year-old girl is brought to the office by her mother. The mother is worriedbecause she noticed some axillary hair development in her daughter. The girl appears calm, and denies the presence of headaches, visual disturbances or abdominal pain. There has been no change in her behavior. Her medical history is unremarkable. Her older sister's pubertal changes began at age 11. Physical examination reveals scarce and dark axillary hair, absent breast development and absent pubic hair. The rest of the examination is unremarkable. Activation of which of the following structures is most likely responsible for this patient's symptomatology?

912. On the second day after birth, a mother reports that her newborn infant does not movehis left hand and his left eyelid droops. On examination, you confirm the findings of the mother and elicit myosis in the left eye. Pregnancy was uneventful, and delivery uncomplicated. Which of the following is the most likely diagnosis?

913. During a physical examination for participation in a sport, a 16 year-old-girl is noted to have a late apical systolic murmur, which is preceded by a click. The rest of the cardiac examination is normal. She states that her mother also has some type of heart “murmur” but knows nothing else about it. Which of the following is the most likely diagnosis?

914. A previously normal newborn infant in a community hospital nursery is noted to be cyanotic at 14 hours of life. She is placed on a face mask with oxygen flowing at 10 L/min. She remains cyanotic, and her pulse oximetry reading does not change. An arterial blood gas shows her PaO2 to be 23 mm Hg. Bilateral breath sounds are present, and she has no murmur. She is breathing deeply and quickly, but she is not retracting. While you are waiting for the transport team from the nearby children’s hospital, you should initiate which of the following?

915. A 14-month-old male infant presents to the emergency room with a chief complaint of high grade fever with no response to antipyretic therapy. This illness started suddenly with the abrupt onset of fever early yesterday morning. He then developed a severe cough and increased work of breathing. The mother reports that he is frequently ill. He was hospitalized 2 months ago for pneumococcal pneumonia. On examination: PR: 145/min; RR: 55/min; BP 100/60mm Hg; oxygen saturation 91%; weight 7 kg (154 lbs). He is listless, tired, and small for age. Both ear canals contain purulent drainage. An immunologic work-up is done and found to have markedly elevated IgM, undetectable IgG and IgA with diminished total B- lymphocytes and neutrophils. Which of the following is the most likely diagnosis?

916. A 4-year-old girl is brought to the office due to easy bruising and a rash for the past 3 days. She had an upper respiratory infection approximately two weeks ago. She has never had palpable bruises, hemarthroses, or deep muscle bleeding in the past. She has 2 older brothers, neither of which has had bleeding symptoms before. Her family history is negative for any bleeding disorders. Her vital signs are normal. Physical examination reveals a diffuse petechial rash on her neck, trunk, extremities and groin. There is no hepatosplenomegaly. Nonpalpable ecchymoses of varying ages are present on the shins and arms. The laboratory findings are as follows: Hemoglobin 12 .8 g/dl Hematocrit 38.5% WBC 6,000/mm3 Platelets 5,000/mm3 PT 12.0 sec PTT 30 sec Peripheral smear shows normal morphology of the red and white blood cell lines. The platelets are reduced in number, and majority of them are increased in size. What is the most likely diagnosis?

917. A 1-year-old patient is in the office for a health maintenance visit and is ready forimmunizations. The child has a mild upper respiratory infection and a low-grade fever. The mother does not want the child to receive vaccine because she has been told that the vaccine could make the illness worse. You tell her the only true contraindication to vaccination is which of the following?

918. An athletic 12-year-old boy complains of left knee pain when he runs and plays sports. The pain resolves when he rests. He has otherwise been well. His physical examination is normal, except for swelling and increased prominence over the left tibial tubercle. A radiograph of the left knee is normal. Which of the following is the most likely diagnosis?

E. Hemophilia B 922. A 23-year-old primigravida comes to the physician for a prenatal visit. She is considering breastfeeding her infant, and the physician discusses the benefits of breastfeeding for both the mother and the infant. She asks if there are any reasons that she should not breastfeed. Which of the following maternal conditions is a contraindication to breastfeeding?

923. a 3-day-old newborn is ready to be discharged from the neonatal nursery, when hismother reports that a rash has appeared on his abdomen and chest. He otherwise appears healthy. He has no fever and no risk factors for infection. Examination reveals a nontoxic neonate with erythematous papules and vesicles surrounded by patches of erythema. Microscopic evaluation of the pustules reveals numerous eosinophils. What is the most likely diagnosis?

924. A 5-year-old child develops an earache, but her mother is too busy to take her to the pediatrician. Two weeks later, the child still has not improved and now has a painful, swollen, red area behind the pinna. At this point, the child is taken to the emergency department, where the physician additionally notes the presence of fever and a creamy discharge in the ear canal. Which of the following is the most likely diagnosis?

925. A 3-year-old girl is believed to have swallowed a marble. She presents to the emergency department unable to speak and begins to become cyanotic. Initial attempts at endotracheal intubation are unsuccessful. Which of the following is the most appropriate next step in management?

926. An infant is brought to a hospital because her wet diapers turn black when they are exposed to air. Physical examination is normal. Urine is positive both for reducing substance and when tested with ferric chloride. This disorder is caused by a deficiency of which of the following?

927. A 7-year-old girl complains of increased urinary frequency, dysuria and itching on urination. Her urinalysis is consistent with a urinary tract infection. This is her 20th infection in the past year, despite adequate antibiotic coverage. Further imaging of her bladder, kidneys and ureter reveals is consistent with vesicoureteral reflux. Which of the following is the next appropriate step?

928. A mother brings her 3-year-old son to the pediatrician because he has had 7 days of fever and a painful swollen lymph node in his right groin. This is the boy's sixth episode of lymph node swelling; previous episodes resolved after drainage and prolonged antibiotic therapy. The child also has a past medical history significant for pneumonia at 12 months of age that required chest tube placement for drainage. His maternal uncle died in childhood from recurrent infections. On examination, the boy is at the 5th percentile for both height and weight His temperature is 38.5 c (101.3 F). There is an enlarged, tender lymph node in the right inguinal area with erythema and warmth of the overlying skin. There are several healed incisions in the inguinal regions bilaterally, as well as around the neck from old drainage sites. Laboratory analyses reveal the following: Hematocrit 35% Platelet count 350,000/mm3 Leukocyte count 17000/mm3 Segmented neutrophils 65% Bands 10% Lymphocytes 25% Gram stain of fluid aspirated from the affected lymph node reveals numerous bacteria-filled segmented neutrophils. Cultures grow S. aureus. What is the most likely mechanism underlying these findings?

929. A 7-year-old boy has cramping abdominal pain and a rash mainly on the back of hislegs and buttocks as well as on the extensor surfaces of his forearms. Laboratory analysis reveals proteinuria and microhematuria. You diagnose Henoch-Schönlein, or anaphylactoid, purpura. In addition to his rash and abdominal pain, what other finding is he likely to have?

930. A 21-year-old woman presents to the emergency room in active labor. She has had no prenatal care, but her last menstrual period was approximately 9 months prior. Her membranes are artificially ruptured, yielding no amniotic fluid. She delivers an 1800-g (4-lb) term infant who develops significant respiratory distress immediately at birth. The first chest radiograph on this infant demonstrates hypoplastic lungs. After this infant is stabilized, which of the following is the most appropriate next step for this infant?

931. A pediatrician is called to the delivery room because a full-term infant has developed cyanosis and respiratory distress immediately after birth. A brief examination of the infant reveals cyanosis on room air not completely relieved by oxygen administered by mask, subcostal and intercostal retractions, absent air entry on the left with audible bowel sounds in the left chest, and poor air entry on the right chest. The heart is best heard in the right hemithorax; the abdomen is flat without organomegaly. Which of the following is the most likely diagnosis?

932. A blood type B infant born to a blood type O mother has clinically significant fetal- maternal blood group incompatibility with mild anemia and a weakly positive Coombs test. The infant develops jaundice a few hours after birth, with a bilirubin (measured at 12 hours after birth) of 12 mg/dL (predominately unconjugated) compared with 3.5 mg/dL in cord blood. The physician is concerned that the rising bilirubin levels will damage the infant's nervous system. Which of the following sites is most vulnerable to this injury?

933. A 15-year-old girl is brought to the pediatrician's office because of sudden deterioration of school performance. Over the past month, her mother has noticed an occasional paint stain on the girl's hands. Her mother also noticed six bottles of typewriter correction fluid in her bedroom about a week ago. She raised the concern of inhalant abuse. Which of the following is the most likely consequence of chronic inhalant abuse?

934. A 4-year-old child comes in for a health maintenance visit. His mother is concerned that he is not doing some things that other kids in his preschool do. Which of the following skills would be expected of a 4-year-old?

935. A 5-year-old boy is brought to the emergency department with high-grade fevers, irritability, dyspnea and difficulty swallowing that started just hours ago. His mother reports that he had been well before going to bed, but then awoke in the middle of the night with respiratory distress. His vaccination history is uncertain. On physical examination, his temperature is 39. 1 °C (102 .4°F), pulse is 130/min, and respirations are 46/min. He appears anxious and restless, and he is drooling. While observing his respirations, you note that inspiring causes him particular distress. There is no stridor. Sitting upright with his neck hyperextended seems to give the child some relief. Which of the following is the most likely diagnosis?

936. A 3-year-old boy is brought to the clinic due to an abdominal mass that his mothernoted while she was bathing him. She seems distressed about the matter, and seeks your "expert opinion." The patient does not have any significant past medical history. On examination, he is calm and quiet. A firm abdominal mass is palpated in the left quadrant, which does not cross the midline. The mass is tender on deep palpation, but is not pulsatile Urinalysis reveals a trace amount of blood. What is the most likely diagnosis?

937. A 7-day-old female neonate is brought to your office for a 2-day history of jaundice and poor feeding. According to the mother, she has vomited twice but doesn't appear febrile. She is regularly breastfed. Her birth history is unremarkable. On examination, she appears listless, and mild jaundice, along with signs of dehydration, are noted. Her blood pressure is 78/52mm Hg, pulse rate is 150/min, and temperature is 36 C (96 F). Her family history is insignificant. What is the most appropriate next step in the management of this patient?

938. The father of a 1-week-old infant comes to the office in a panic. He has just noticed on his child a right anterior shoulder mass that seems ten- der. The father is an osteosarcoma survivor and fears the child has the same malignancy. In reviewing the baby’s discharge papers, you note the child was a term, appropriate-for-gestational-age vaginal delivery with a birth weight of 3200 g (7 lb, 1 oz). Apgar scores were 9 at 1 and 5 minutes. Your examination is significant for a large firm mass on the right clavicle; the rest of the examination is normal. Management of this problem should include which of the following?

939. A 1-day-old infant who was born by a difficult forceps delivery is alert and active. She does not move her left arm spontaneously or during a Moro reflex. Rather, she prefers to maintain it internally rotated by her side with the forearm extended and pronated. The rest of her physical examination is normal. This clinical scenario most likely indicates which of the following?

940. A 2-year-old girl is brought to the physician because of protracted irritability, crying, and loss of appetite. She recently had a sore throat. Her temperature is 38.5 C (101.3 F). Physical examination is unremarkable, except for abnormalities of the tympanic membrane detected on otoscopic examination. Which of the following signs or symptoms correlates best with a diagnosis of acute otitis media?

A 3-month-old infant is taken to the emergency department with constipation and behavioral changes. Physical examination demonstrates ptosis and an absence of facial expression. The child appears conscious but has trouble following a toy with her gaze. The crying is very weak, and saliva is pooling in her mouth. She is also developing a generalized hypotonia, and breathing is becoming more shallow. This child's condition is most likely related to ingestion of which of the following food products?

942. A 5-week-old infant is brought to the clinic for a 4-week history of noisy breathing that has not improved. She has otherwise been healthy except for a current upper respiratory infection for the past 4 days, which according to the parents, has worsened the noisy breathing. On examination, she has inspiratory stridor. The noisy breathing improves when the infant is asleep. Which of the following is the most likely diagnosis?

943. A 3-week-old boy presents to the physician's office with a 1-week history of forceful, projectile vomiting. He has been vomiting after almost every feeding. The vomitus contains mostly undigested formula and is non-bilious. On examination, his oral mucosa is dry, his anterior fontanel appears to be depressed, and his capillary refill is 3-4 seconds. An abdominal examination reveals an olive-sized mass in the epigastrium. Which of the following electrolyte findings will most likely be seen?

944. A 15-day-old male infant is brought to the emergency department by his mother due to vomiting and bloodstained stools since yesterday. The vomitus is green. Recently, the neonate has been feeding poorly. His birth history is not significant: he was absolutely normal and passed meconium within the first 12 hours of life. He has been breastfed since birth. His pulse rate is 122/min and blood pressure is 80/50mm Hg. He is irritable, his mucous membranes are dry, and his abdomen is distended. Based on these findings, what is the most likely diagnosis?

945. A married couple brings their 2-week-old infant to the office for the evaluation of lethargy, poor feeding and hypotonia. The infant was "fine" until yesterday, when he started to present with these symptoms. The mother's medical history is unremarkable, and her pregnancy was uneventful. On examination, hypotonia, poor reflexes and bulging fontanel are noted. There are no focal neurological signs. He is hypotensive and tachycardiac. His temperature is 39.4 C (103F). Initial investigation reveals a WBC count of 16,000/mm3 with 18% bands. What is the most likely diagnosis?

946. A 16-year-old girl is in your office for a pre participation sports examination. Sheplans to play soccer in the fall, and needs her form filled out. Which of the following history or physical examination findings is usually considered a contraindication to playing contact sports?

947. A 15-year-old boy is in the office for a preparticipation sports physical examination before he begins playing with the varsity football team at his school. Although he is a skilled receiver, he will be one of the smallest players on the field and is concerned about the potential for injury. He asks how to bulk up. Appropriate advice to increase muscle mass includes which of the following?

948. An 18-year-old male college student is seen in the student health clinic for urinary frequency, dysuria, and urethral discharge. Which of the following is likely to explain his condition?

949. A neonate is markedly edematous and dies 1 hour after birth. A diagnosis of hydrops fetalis is made after the hematocrit on cord blood is demonstrated to be 5%. The erythrocytes in a smear from the cord blood are markedly hypochromatic. The mother is Rh positive and is known to have alpha-thalassemia trait. The thalassemia status of the father is unknown. Alpha-thalassemia is the suspected cause of the infant's hydrops. Which of the following hemoglobins would most likely be markedly elevated in this infant's blood if this diagnosis were correct?

950. A 1-year-old girl is brought to the emergency department by her mother because the child's "eyes and feet are dancing." On physical examination, the girl is well developed and in no acute distress. Her temperature 37.0 C (98.6 F), blood pressure is 100/55 mm Hg, pulse is 100/min, and respirations are 20/min. The patient has opsoclonus, myoclonus, and ptosis of the right eye. On history, the mother notes the child was born "looking like a blueberry muffin" and has had a persistent cough since the age of 2 months. Which of the following is the most likely diagnosis?

951. A 19-year-old male college student returns from spring break in Fort Lauderdale, Florida, with complaints of acute pain and swelling of the scrotum. Physical examination reveals an exquisitely tender, swollen right testis that is rather hard to examine. The cremasteric reflex is absent, but there is no swelling in the inguinal area. The rest of his genitourinary examination appears to be normal. A urine dip is negative for red and white blood cells. Which of the following is the appropriate next step in management?

952. A 16-year-old girl presents with lower abdominal pain and fever. On physical examination, a tender adnexal mass is felt. Further questioning in private reveals the following: she has a new sexual partner; her periods are irregular; she has a vaginal discharge. Which of the following is the most likely diagnosis?

953. A 6-year-old girl with acute lymphocytic leukemia (ALL) is admitted to the hospital with a generalized vesicular rash and high fever. She has no previous history of chickenpox and has never received immunization for varicella. Her 4-year-old sister recently recovered from chickenpox that started about 10 days ago. On admission, her temperature is 38.4 C (101.1 F), blood pressure is 94/58 mm Hg, pulse is 80/min, and respirations are 20/min. Which of the following is the most serious complication of varicella that might occur in this patient?

954. A 5-year-old boy suddenly begins coughing while eating peanuts. He is choking and gagging. When he is brought to the emergency department, but he is awake and is able to give his name. On physical examination, his vital signs are stable. On examination of the chest, inspiratory stridor and intercostal and suprasternal retractions are apparent. Which of the following is the most appropriate initial step in management?

9-year-old boy is rushed to the emergency department after having a seizure. He is visiting his grandparents for the weekend. His past medical history is insignificant. When the grandmother is questioned about any medications, she replies with, "He isn't taking any medications, but I'm taking nortriptyline, and my husband is taking atenolol and enalapril." The boy's blood pressure is 80/40 mmHg and pulse is 90/min. Physical examination reveals dry oral mucosa and dilated pupils. His answers are adequate, but delayed. EKG shows wide QRS complexes. What is the best next step in the management of this patient?

956. A 1-month-old infant is brought to the office for a routine neonatal visit. His prenatal and birth histories are unremarkable. His vital signs are normal. Examination reveals a harsh, loud holosystolic murmur over the left, lower sternal border. Palpation reveals a thrill over the precordial region. There is no cyanosis, and pulmonary auscultation reveals no rales. Chest radiograph reveals a heart of normal size and a slight increase in pulmonary vascularity. EKG is normal. Which of the following is the most appropriate course of action?

958. A 12-year-old boy comes to the emergency department at midnight with a complaint of severe scrotal pain since 7 PM. There is no history of trauma. Which of the following is the most appropriate first step in management?

959. A 12-year-old boy presents with an intensely pruritic rash for 3 days. He just went on a camping trip, during which he wore only short-sleeve shirts and short pants. His  temperature is 37.6 C (99.7 F), blood pressure is 96/62 mm Hg, pulse is 65/min, and respirations are 12/min. There are numerous erythematous papules and vesicles on both arms and legs. Most of them are in a linear array. Which of the following is the most appropriate pharmacotherapy?

960. A premature infant has a difficult delivery with episodes of arrhythmia and suspected hypoxiaischemia. After the delivery, the infant is lethargic and has periods of apnea. Intracranial hemorrhage is suspected. No obvious head trauma is noted. Cranial ultrasound identifies blood within the ventricles. Which of the following structures is the most likely source of the hemorrhage?

961. The mother of a 2-year-old girl reports that her daughter complains of burning when she urinates and that she has foul-smelling discharge from her vagina. She has some slight staining on the front of her underwear, but denies fever, nausea, vomiting, or other constitutional signs. The child does not attend day care, and she has demonstrated no change in behavior. The physical examination is normal with an intact hymen, but the child’s vulva is reddened and with a malodorous scent noted. Her urinalysis and culture are normal. Management of this condition includes which of the following?

962. A 4-year-old child is observed to hold his eyelids open with his fingers and to close one eye periodically, especially in the evening. He has some trouble swallowing his food. He usually appears sad, although he laughs often enough. He can throw a ball, and he runs well. Which of the following is most likely to aid in the diagnosis?

963. An 8-year-old girl is being evaluated for short stature. She is at 8th percentile for height and 30th percentile for weight. Vital signs are within normal limits. Examination shows a high arched palate and inverted, widely spaced nipples Karyotyping shows 45 XO. Which of the following is she most at risk of developing?

964. A female infant is born full-term to a 24-year-old Caucasian primigravida. The delivery was uncomplicated. The Apgar scores were 7 and 8 at 1 and 5 minutes, respectively. The prenatal course was complicated with asymptomatic bacteriuria that was treated with an antibiotic. The mother took multivitamins during her last trimester, occasionally took acetaminophen for back pain throughout the pregnancy, and denies smoking and alcohol consumption. Physical examination of the infant reveals a blood-tinged vaginal discharge and bilaterally enlarged mammary glands. What is the best next step in the management of this patient?

965. Awakening at night. His mother states that when he wakes up suddenly, he screams, "Go! Get away! Go!" and does not respond to the parents. His eyes are wide open, and he sweats heavily and looks scared. The parents have had to struggle to awaken him. After the episodes, he has no memory of what happened. Which of the following is the most likely diagnosis?

966. A 15-year-old boy comes to the physician for advice about his facial acne. On examination, the patient has mild to moderate acne, mostly consisting of open comedones, some closed comedones, and a few pustules on the forehead and cheeks. Which of the following is the best advice to give this patient?

967. The parents of a 16-year-old girl complain that she does not get enough sleep. They recently discovered that she stays awake most nights until 1:00 AM reading and text messaging her friends. She wakes at 6:30 AM for school, and complains of sleepiness during the day. On weekends she sleeps until noon. Her parents have tried taking away her computer and phone, but she still would go to bed at the same time. The parents are looking for advice in dealing with their “night owl” daughter. Which of the following is appropriate advice for this family?

968. A 2-year-old girl is brought to the emergency department due to severe, sudden-onset abdominal pain. She has nausea and vomiting, and her stools contain blood and mucus. Her parents say that she was in her usual state of health when she developed this problem. Her A 9-year-old boy presents with a 3-month history of multiple episodes of sudden pulse rate is 116/min, blood pressure is 90/60mm Hg, temperature is 37.7C (100F), and respirations are 28/min. She looks lethargic and ill. She is crying and drawing her knees towards her chest. Her abdomen is tender to palpation, and there is a palpable, sausage-like abdominal mass. The bowel sounds are increased, and rectal examination reveals bloody mucus. What is the most likely cause of her symptoms?

969.A neonate born at term is found to have webbed neck and swollen hands and feet. 969. Ultrasonogram of the abdomen shows a horseshoe kidney. Which of the following is the most likely cause of edema?

970. A 5-year-old boy is brought to his pediatrician's office after he falls from his bicycles and strikes his head against the sidewalk. There were no witnesses to this incident, which occurred 8 hours ago. The child is otherwise healthy, up-to-date on his immunizations, and not taking any medications. On physical examination, his vital signs are stable. He has a 5 × 4 cm abrasion on his forehead. He is alert and oriented to date, place and self. His motor and sensory examinations are normal and reflexes are normal. Which of the following constitutes reasonable management?

971. A 3-week-old African American boy is brought to the Emergency Department because of a generalized seizure 2 hours ago. The infant is highly irritable with incessant high pitched crying. The infant's weight is 2.5 kg (250 gm below birth weight), blood pressure is 70 /40 mm Hg, pulse is 145/min and respirations are 50/min. Laboratory results show: Blood glucose 120 mg/dL Urea nitrogen 50 mg/dL Serum sodium 170 mEq/L Serum calcium 8.5 mg/dL Serum magnesium 1.5 mg/dL Which of the following is the most likely cause of this infants seizure?

972. A 3-year-old-boy ingests 40 of his older sister's chewable vitamin tablets, as well as 3 tablets of 250 mg of acetaminophen. The ingredients in the multivitamin tablets are as follows: Vitamin A 3000 IU Thiamine 1 mg Vitamin C 75 mg Immune mediated red cell destruction Dysgenesis of the lymphatic network@ Decreased synthesis of albumin Increased urinary loss of protein Severe intrauterine hypoxia A 5-year-old boy is brought to his pediatrician's office after he falls from his bicycle Vitamin B6 1 mg Vitamin D 400 IU Iron 12 mg Fluoride 1 mg The child is brought to the emergency department in no acute distress. Which of the following complications may occur if appropriate therapy is not undertaken?

973. A 7-year-old boy presents with tenderness and erythema of one knee joint. He has had troubles with infections since about 3 months of age. A brother and a maternal uncle both died of infectious disease at an early age. A detailed immunologic evaluation performed at 2 years of age demonstrated plasma IgG less than 50 mg/100 mL. Normal numbers of circulating T cells and normal cellular immunity were found. The boy had been treated monthly since then with IV immunoglobulin. This therapy had markedly reduced, but not eliminated, the boy's infection rate. Which of the following is the most likely pathogen to cause infectious arthritis in this patient?

974. You are examining a newborn infant in the well-baby nursery. The infant was the product of a benign pregnancy and vaginal delivery; he appears to be in no distress. Interestingly, your measurement of fronto- occipital head circumference is about 2 cm larger than the initial measurement done several hours before. Your examination otherwise is significant for tachycardia and a “squishy” feel to the entire scalp. You can elicit a fluid wave over the scalp. Management of this condition should include which of the following?

976. A 1-year-old Caucasian boy is brought to your office with necrotic periodontal infection. The past medical history is significant for recurrent cutaneous and sinus infections revealing S. Aureus and P. Aeruginosa isolates. The separation of the umbilical cord was delayed (4 weeks). CBC shows leukocytosis and increased neutrophils. The number of peripheral lymphocytes is normal. Gamma-globulin level is increased on plasma protein electrophoresis. The Nitroblue tetrazolium (NBT) test is normal. Which of the following is the most likely defect present in this patient?

977. A 6-week-old girl comes to medical attention because of a bright red plaque on her neck. The plaque is slightly raised, measures 2 cm in greatest diameter, and blanches partially on pressure. The mother reports that the lesion appeared in the second or third week and has been gradually increasing in size. Which of the following is the most appropriate next step in management?

978. A 15-year-old girl presents to a pediatric cardiology clinic with a complaint of chest pain. She states the pain has come and gone over the past year, but has increased in frequency over the past few weeks. She describes it as a sharp pain over her left chest. Physical examination reveals a healthy-appearing 15-year-old girl. Her temperature is 37.2 C (99 F), pulse is 90/min, and respiratory rate is 20/min. Lung examination is normal. Cardiac examination reveals a late systolic murmur preceded by a click at the apex. No heave or rub is Adenosine deaminase deficiency Complement deficiency Opsonization defect Destruction ofT lymphocytes Impaired leukocyte adhesion@ A 6-week-old girl comes to medical attention because of a bright red plaque on her present. An electrocardiogram and chest x-ray film are unremarkable. Which of the following is the most likely diagnosis?

979. Within 8 hours after birth, an infant has "excessive salivation." Physical examination reveals that she has an imperforate anus, with a small fistula to the vagina. A small, soft nasogastric tube is inserted, and the infant is taken to xray. The film shows the tube coiled back on itself in the upper chest, and a normal gas pattern in the gastrointestinal tract. There are no apparent abnormalities of the radius or the vertebral bodies. Which of the following is the most appropriate next step in management?

980. An 8-year-old girl is brought to the pediatrician's office for evaluation of new onset swelling around the eyes. Physical examination reveals periorbital, sacral, and pretibial edema; her blood pressure is 96/64 mm Hg. The rest other physical examination is normal. Which of the following is the most appropriate initial diagnostic study?

981. A 6-year-old child has had repeated episodes of otitis media. She undergoes an uneventful surgical placement of pressure-equalization (PE) tubes. In the recovery room she develops a fever of 40C (104F), rigidity of her muscles, and metabolic and respiratory acidosis. Which of the following is the most likely explanation for her condition?

982. The 7-year-old boy now in your office was last seen 2 weeks ago with a mild viral upper respiratory tract infection. Today, however, he presents with fever, ataxia, weakness, headache, and emesis. In the office he has a 3 minutes left-sided tonic-clonic seizure. You send him to the hospital and order a magnetic resonance imaging (MRI) of the brain, the results of which show disseminated multifocal white matter lesions that enhance with contrast. This boy’s likely diagnosis is which of the following?

A 10-year-old African American boy is brought to the office for the evaluation of worsening fatigue for the past few weeks. He has sickle cell anemia, and has had several hospitalizations for painful crises. His vital signs are stable. He appears pale. He has a hemoglobin level of 7. 7 g/dl and hematocrit of 22.5%. Which is the most likely type of anemia of this patient?

984.increasing fatigue. He was well until 2 weeks ago when he had an upper respiratory illness (URI). He has a decreased appetite and has lost 2 lbs over the last 2 weeks. He has some shortness of breath when he climbs the stairs. His past medical history is unremarkable. On examination his vital signs are normal, and his height and weight are at the 80th percentile. His conjunctiva are pale, and he has bilateral, mobile (about 1-2cm) and non-tender nodes in the cervical, axillary, and inguinal regions. Hepatosplenomegaly is present, and skin shows no lesions. Labs are Hemoglobin 7.3g/dl, platelet count 20,000/mm3, WBC count 42,100/mm3, with 24% lymphoblasts, 70% lymphocytes, and 6% atypical lymphocytes. Chest X-rays show clear lung fields but a wide mediastinum. Which of the following is the most likely diagnosis

985. A 7-year-old boy is referred by his school for psychiatric evaluation. The teachers have noticed that, in the past year, he has been unable to sustain attention in class, and has been fidgeting and talking to his peers during class. He seems unable to wait for others to finish speaking and keeps interrupting and blurting out answers before questions are completed. At home, his parents state that he is forgetful and losses things easily. Which of the following is the most likely diagnosis?

986. An 8-year-old boy falls on his right hand with the arm extended, and he breaks his elbow by hyperextension. X-ray films show a supracondylar fracture of the humerus. Which of the following complications is of greatest concern with this type of injury?

987. An 18-year-old girl has hepatosplenomegaly, an intention tremor, dysarthria, dystonia, and deterioration in her school performance. She also developed abnormal urine with excess glucose, protein, and uric acid. She has a several-year history of elevated liver enzymes of unknown etiology. Which of the following best explains her condition?

988. A 3-month-old infant without significant past history was brought to the emergency center by her mother with a generalized tonic-clonic seizure. She is found to have glucose of 5 mg/dL. After correction of her hypoglycemia, she is admitted to your service for further evaluation. Several hours later, her nurse calls to tell you that her bedside glucose check was now 10 mg/dL. You order laboratory work suggested by the pediatric endocrinology team and again correct the infant’s hypoglycemia. The results of the laboratory tests you drew include an elevated serum insulin level of 50 U/mL, and a low IGFBP-1 (plasma insulin-like growth factor binding protein-1). C-peptide levels are not detectable. Which of the following is the likely cause of this child’s recurrent hypoglycemia?

989. A 3-year-old boy is brought to the physician for help with toilet training. He recently started day care and screams "no" when teachers try to place him on the toilet. He has bowel movements every other day and strains when he passes hard, pellet-like stools. The boy is a picky eater but loves milk and drinks up to 30 oz of chocolate milk daily. He has no medical problems and takes no medications. His weight and height have been tracking along the 75th percentile. Examination shows a cooperative, well-nourished boy. He runs well and can climb onto the examination table independently. He speaks in short sentences that are mostly understandable. The boy's abdomen is soft, nontender, and nondistended. He has normal Tanner I male genitalia. A small fissure is noted on the anal verge. Which of the following is the best next step in management of this patient?

990. An African-American boy is in the newborn nursery with a bulge on his abdomen that was identified immediately after birth and is most pronounced during crying. The patient was born to an 18-year-old woman who did not receive prenatal care or take prenatal vitamins. Vitals are normal. Examination shows a soft swelling at the umbilical ring. Which of the following is the most likely diagnosis and best course of action for this patient?

991. A 14-year-old girl is brought to the physician’s office because of irregular menstrual periods. She had her menarche at age 13, and since then her periods have been irregular with the cycles varying from 3 to 6 weeks. She has no other symptoms. Physical examination is unremarkable. She has age appropriate secondary sexual characteristics. A urine pregnancy test is negative. Serum prolactin and thyroid stimulationg hormone levels are normal. Administration of micronized oral progesterone results in withdrawal bleeding in 3 days. Which of the following most likely explains her irregular periods?

992. Parents bring their 17-year-old son to the emergency department due to his strange behavior at times during the past few weeks. The boy is normally polite and soft-spoken, but he has recently become irritable, impatient, and rude. His parents initially dismissed his behavior as a “phase” with the expectatioin that he would grow out of it. However, they became very concerned on discovering that he had stolen money from their wallets and was sleeping erratically. When questioned by his father about his strange behavior, the boy responsed, “I’m on a secret mission. The king of Norway has sent me here to spy on the US government.” His temperature is 36.6 C, BP is 144/94 mmHg, pulse is 118/min, and respirations are 18/min. On physical examination, the patient appears to be irritated. He is sweating profusely and his pupils are dilated. He is observed in the emergency department for several hours, his condition improves, and he is discharged to the care of his parents. Which of the following is the most likely diagnosis?

993. A 7-year-old is brought to the office with sore throat, poor appetite, and malaise over the last 2 days. He has no cough, rhinorrhea, or nasal congestion. The boy takes no medications, has no known allergies, and his immunization are up to date. Temperature is 38.9 C, BP is 110/70 mmHg, pulse is 130/min, and respitations are 16/min. On examination, his tonsils are swollen and covered with thin, with exudates. Small, tender anterior cervical lymph nodes are palpated. What is the most appropriate next step in management of this patient?

994. A 16-year-old girl comes to the physician with headache and vision changes for the past month. The headaches are worse in the morning and are associated with nausea. She takes oral isotretinoin for severe acne. Her temperature is 36.7 C, BP is 130/80 mmHg, Pulse is 70/min, and respirations are 15/min. Eye examination shows papilledema and decreased visual acuity. There is no neck stiffness. Motor examination shows 5/5 strength, 2+ deep- tendon reflexes, and a normal plantar response. Sensory examination is unremarkable. Computed tomography scan of the head is within normal limits. Lumbar puncture shows the following: Opening pressure 280 mm H2O Cerebrospinal fluid glucose 40 mg/dL Cerebrospinal fluid protein 40 mg/dL White blood cells 3/mm3 Which of the following is the most likely cause of this patient’s symptoms?

995. A 12-year-old male child comes to the office after being referred for a medical evaluation. His schoolteacher says that he has a problem concentrating during class. He stares in space for a few seconds several times a day, and appears totally absorbed in his thoughts. He is not disruptive in class, but appears forgetful. There is no history of trauma, infection or problem at birth. On examination, the child is alert with stable vital signs. There is no loss of motor or sensory perceptioin. Which of the following can confirm the patient’s diagnosis?

996. A worried and anxious pregnant mother brings her 3-year-old son to the emergency room after he experienced several episodes of vomiting and abdominal pain for the past two hours. His vomit is coffee ground in appearance. He is irritable and lethargic. His BP is 80/40 mmHg and pulse rate is 120/min. Examination shows a normal oropharynx; chest auscultation is within normal limits. Abdomen is soft and mildly tender at the epigastrium; there is no hepatosplenomegaly. Extremities are cold to touch. Initial laboratory studies show: Hemoglobin 10.3 g/L Leukocyte count 14, 500/mm3 Bicarbonate 18 mEq/L Chest x-ray is normal limits. Abdominal imaging shows radiopaque tablets in the stomach. Intravenous normal saline is started. Which of the following is the most appropriate next step in management?

997. A 12-year-old African American male with known sickle cell disease presents with a 2 hours history of right-sided arm weakness ans slurred speech. He has been hospitalized before for pain crises and pneumonia. He takes hydroxyurea, oxycodones as needed, and folic acid. His temperature is 36.6 C, BP is 153/83 mmHg and HR is 112/min with regular rhythm. On physical examination, he has right arm weakness and mild dysarthria. His laboratory values are the following: Hemoglobin 8.2 mg/dL WBC count 14, 000.mm3 Platelet count 210, 000/mm3 Creatinine 0.9 mg/dL CT of the head shows no evidence of intracranial bleeding. Which of the following is the best initial management for this patient?

998. A 1-day-old full-term boy is in the neonatal intensive care unit with cyanosis. His BP is 80/40 mmHg in all 4 extremities, HR is 140/min, and respirations are 55/min. Pulse oxymetry shows 80% and does not improve with 100% inspired oxygen by face mask. He is breathing comfortably, but his fingertips and oral mucosa are blue. A continuous machine- like murmur is heard on auscultation. Chest x-ray shows clear lung fields bilaterally. Which of the following is the best next step in management of this patient?

999. The parents of a 16-year-old girl bring their daughter to the Emergency Department due to their concerns regarding her recent behavior. Her mother reports, “She has always been a straight “A” student and has had an uneventful childhood until now.” Her developmental and medical history are insignificant except for a diagnosis of asthma when she was eight- years-old. Over the last two months, she has been spending time with new friends, dressing differently, and has become increasingly defiant. This morning, her parents received a call from her school counselor who reported that the patient missed three days of school last week and is in danger of having to attend next course because she is falling math. Last night, she did not return home until 3 am despite the fact that her curfew was 11 pm. The patient is annoyed and states, “What’s the big deal? I was just hanging out with my friends.” Initially, she refused to answer any questions. Her cooperation improves, however, when assessed without her parents present. Review of symptoms was negative and she confirms that her asthma was controlled. She denies abusing any substances. She confirms that her grades have dropped because she is tired of school. She also says, “I really don’t care if I fail, but I’m not going to next course. Me and my friends have plans.” She would not provide any further details. After interviewing both the parents and the adolescent individually, which of the following is the most appropriate course of action?