DES C_Basic (1) Prepared : CHILLY

A neonate is noted to have an abnormally shaped face with a very small jaw. Several hours after birth, the baby develops convulsions and tetany. Serum chemistries show the following: Sodium 1 40 mEq/L, Potassium 4 mEq/L, Chloride 100 mEq/L, Bicarbonate 24 mEq/L, Magnesium 2 mEq/L, Calcium 5 mg/dL, Glucose 100 mg/dL. This child's disorder is associated with aplasia or hypoplasia of which of the following organs?

16 An 18-month-old child is brought to the emergency department by his mother due to a one-day history of lethargy and anorexia. He had a fever the whole day yesterday, which responded to Tylenol (Acetaminophen). He then developed a petechial rash over his entire body, which worsened in the last few hours. He is up-to-date with his immunizations, and is an otherwise healthy baby. On examination, he is drowsy and lethargic. He has neck stiffness and appears septic. He flexes his hips when his neck is flexed. What is the most likely organism responsible for the patient's symptoms?

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 (103° F), 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?

A 1-day-old boy is evaluated in the nursery for minimal right arm movement. He was born at 41 weeks gestation to a woman with poorly controlled type 1 diabetes mellitus. Attempted vaginal delivery was complicated by shoulder dystocia and became a cesarean section delivery. Family history is positive for obesity in the boy's father and osteoporosis in both grandmothers. Birth weight was 4.5 kg. Examination shows crepitus and irregularity over the right clavicle. Moro reflex is absent on the right. Bilateral biceps and grasp reflexes are intact and symmetric. The infant is plethoric and has excessive fat accumulation in the abdominal and scapular regions. The remainder of the examination is normal. Which of the following is the most significant risk factor for this patient's condition?

A 1-day-old infant appears dusky in the newborn nursery during feeding. Oxygen is immediately administered by nasal cannula. Shortly afterward, she develops tachypnea. On physical examination, her blood pressure from the right upper arm is 50/30 mm Hg, her pulse is 180/min, and her respirations are 60/min. An echocardiogram is consistent with hypoplastic left heart syndrome. Which of the following would likely be found on auscultation?

A 1-week-old female infant is brought to the office by her 30-year-old African-American mother because she has been "crying a lot." She was born at term. Her mother was diagnosed with gestational diabetes mellitus (GDM) at 24 weeks gestation and had been on insulin injections since. During labor, there was a prolonged second stage due to difficulty in delivering the shoulders. Her Apgar scores were 8 and 10 at 1 and 5 minutes, respectively. Her birth weight is 3.8 kg (8.5 Ib). On examination, the infant is active. On sudden extension of the head, there is extension of all the extremities, except for the left upper extremity. There is crepitus over the left clavicular bone. Which of the following statements is true for this baby?

A 1-week-old infant is brought to the emergency department due to vomiting and poor feeding. The prenatal and birth histories are unremarkable. The infant's pulse is 140/min, temperature is 37 C (98.7 F), and capillary refill is 2 sec. He has sunken eyes, depressed anterior fontanel, and dry mucus membranes; skin elasticity is reduced. Heart and lungs are clear. There is no abdominal mass. Genital examination shows enlarged clitoris, and fusion of the labioscrotal folds. The initial laboratory work-up reveals the following: Sodium 128 mEq/L, Potassium 5.8 mEq/L, BUN 25 mg/dl. If this patient's karyotype is 46 XX, which of the following is most likely to be increased in this patient's serum?

A 1-week-old male newborn is seen in the office for "noisy breathing." The mother says that the "noisy breathing" is more prominent when the infant is lying on his back, and improves when he is in a prone position with his chin up. The newborn is afebrile and has no cough, vomiting, or cyanosis. There are no inspiratory retractions or wheezes. On direct laryngoscopy, the epiglottis is rolled in from side to side. Which of the following statements is true about the child's condition?

A 1-year-old boy is brought to the physician by his parents for evaluation of bruising and blood in his stool. The child has had multiple episodes of otitis media and has been hospitalized twice with pneumonia, but has never had bleeding or easy bruising in the past. He has been eating and drinking well with no vomiting or diarrhea. He is afebrile with a heart rate of 150/min and a blood pressure of 80/40 mmHg. On examination, he is well-developed, well-nourished, and has a fair complexion. There are dry, scaly patches on his cheeks and lower extremities. He also has bruising and purpura on his lower extremities. His diaper contains a small amount of occult blood positive stool, but no fissures are seen on rectal examination. The remainder of the physical examination is unremarkable. Laboratory studies show: Complete blood count: Hemoglobin 11 .5 g/dL, Platelet count 20,000/mm3, Leukocyte count 6,500/mm3, Neutrophils 76%, Eosinophils 1%, Lymphocytes 13%, Monocytes 10%. A peripheral smear reveals a low number of platelets, and the platelets that are seen are small. Which of the following is the most likely cause of his bleeding?

A 1-year-old boy presents with the complaint from his parents of “not developing normally.” He was the product of an uneventful term pregnancy and delivery, and reportedly was normal at birth. His previous health-care provider noted his developmental delay, and also noted that the child seemed to have an enlarged spleen and liver. On your examination, you confirm the developmental delay and the hepatosplenomegaly, and also notice that the child has short stature, macrocephaly, hirsutism, a coarse facies, and decreased joint mobility. Which of the following is the most likely etiology of his condition?

A 1-year-old child with ALL in remission for 3 months is in the office for a health maintenance visit. He is due for multiple vaccinations including hepatitis B vaccine, inactivated polio vaccine (IPV), varicella vaccine H. influenzae B vaccine (Hib), and pneumococcal vaccine (PCV). You remember that some of these vaccines are live attenuated viruses and are contraindicated in immunocompromised patients. Which vaccine will you not give to this patient?

A 1-year-old patient is in the office for a health maintenance visit and is ready for immunizations. 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?

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?

A 10-year-old boy comes to the office with fever and chills for 5 days and myalgia. He has recently returned from a 2-week vacation to New England with his family. On physical examination he has mild splenomegaly. Which of the following is the most likely cause of his symptoms?

A 10-year-old boy is admitted to the hospital because of bleeding. Pertinent laboratory findings include a platelet count of 50,000/µL, prothrombin time (PT) of 15 seconds (control 11.5 seconds), activated partial thromboplastin time (aPTT) of 51 seconds (control 36 seconds), thrombin time (TT) of 13.7 seconds (control 10.5 seconds), and factor VIII level of 14% (normal 38%-178%). Which of the following is the most likely cause of his bleeding?

A 10-year-old boy presents with fever, headache, photophobia, and neck discomfort in the middle of summer. He is alert and oriented, but has neck pain with flexion and extension of the head. His fundi are normal, and there are no focal neurologic findings or skin changes. A lumbar puncture reveals normal protein and glucose with a cell count of 240/mL (90% lymphocytes). Which of the following is the most likely causative organism?

A 10-year-old boy was healthy until about 10 days ago when he developed 7 days of fever, chills, severe muscle pain, pharyngitis, headache, scleral injection, photophobia, and cervical adenopathy. After 7 days of symptoms he seemed to get better, but yesterday he developed fever, nausea, emesis, headache and mild nuchal rigidity. Cerebrospinal fluid (CSF) shows 200 white blood cells (WBC) per microliter (all monocytes) and an elevated protein. Correct statements about this infection include which of the following?

A 10-year-old girl has bullous target lesions and mucosal erythema, which developed after her third dose of trimethoprim-sulfamethoxazole for a urinary tract infection. Which of the following is a likely associated clinical finding?

A 10-year-old male fell while riding his scooter down a steep hill. In the Emergency Department, his injuries included a fractured wrist and a lacerated spleen, which required surgical removal. Two years later he is diagnosed with bacterial pneumonia. Which of the following bacterial agents is the most likely pathogen for this patient's pneumonia?

A 10-year-old presents with 2 months history of heavy menstrual-like bleeding. Menarche occurred 6 months ago and this first menses consisted of spotting for 3-4 days without cramps. Subsequent periods were light in flow but lasted 6 to 8 days. Which of the following is the most likely cause of her bleeding?

A 12-month-old patient has allergies to multiple foods. The child’s mother has eliminated the foods from the diet and wants to know if these allergies will be lifelong. You tell her that some allergies do get better if the food is eliminated for 1–2 years. In which of the following is the allergy most likely to resolve, with elimination of the food from the diet?

A 12-year-old African American boy is brought to the office due to a 2-day history of high-grade fever and chills. He was apparently well before the onset of fever. He has no bone pain. He has sickle cell disease and has had 4 hospitalizations for painful crises and one episode of osteomyelitis. His blood pressure is 90/60 mm Hg, pulse is 100/min, respirations are 22/min and temperature is 38.9 C (102F). He appears drowsy. His laboratory report shows a total WBC count of 16,000/mm3 with 12% bands and Hb of 9.0 g/dl. Which of the following is the most likely cause of this patient's condition?

A 12-year-old African American male is found to have a murmur during a routine sports physical. He has a family history of sudden death at a young age. It is a harsh crescendo-decrescendo murmur that begins after S1 and is best heard at the left lower sternal border. Valsalva maneuver intensifies the murmur. Which of the following is the most likely mitral valve abnormality in this patient?

A 12-year-old boy is brought to the clinic by his parents because "he cannot walk anymore." Yesterday, he became irritable, uneasy, and complained of tingling and weakness in both his legs. This morning, he couldn't stand up or move his legs, and complained of pain in his leg and thigh muscles. He denies any headaches, nausea or vomiting. He had an episode of febrile diarrhea 10 days ago. His family history is unremarkable. Physical examination reveals symmetric flaccid paralysis of both legs, absent deep tendon reflexes, and decreased superficial touch and vibratory sense. There is no nuchal rigidity. What structure is most likely affected in this patient's condition?

A 12-year-old boy is brought to the emergency department because of severe pain near his left knee. He has sickle cell disease and has been hospitalized previously for sickle cell crisis. Vital signs are notable for persistent fever. Examination of the left lower extremity reveals a normal knee joint with marked tenderness and swelling over the proximal tibia. Laboratory studies show leukocytosis and elevated ESR. Imaging studies confirm the diagnosis of osteomyelitis. Which of the following organisms is the most likely cause of his condition?

A 12-year-old boy is brought to the emergency department with a temperature of 39.1 C (102.4 F) at home, difficulty speaking, and odynophagia for 2 days, Physical examination reveals marked erythema of the right tonsil pillar and edema of the uvula with deviation to the left. In addition to anaerobic bacteria, which of the following organisms is most likely to be isolated from a tonsillar pillar aspirate?

A 12-year-old girl comes to the physician because of a 2-day history of periorbital edema and abdominal distention. She has no other complaints. She has never been diagnosed with hypertension. Her father died at the age of 40, with renal failure. Her temperature is 37.1°C (98.9°F), blood pressure is 125/75 mm Hg, pulse is 80/min, and respirations are 14/min. Examination shows facial puffiness, shifting dullness, and 1+ bilateral pitting pedal edema. Urinalysis shows 3+ proteinuria and lipid laden casts. 24-hour urinary protein excretion is 5 g/day, total serum protein is 4.5 g/dl and serum albumin is 2.3 g/dl. Which of the following is this patient at increased risk of developing?

A 12-year-old girl comes to the physician for an annual examination. She has been in good health for the past year and has no complaints. She began having menses this year and, after a few irregular cycles, is now having a monthly period. Past medical history is significant for multiple episodes of otitis media as a child. Past surgical history is unremarkable. She takes no medications and has no known drug allergies. Physical examination is unremarkable. If not currently immune, which of the following immunizations should this patient most likely receive?

A 12-year-old girl comes to the physician for chronic weight loss and fatigue. She has a history of bulky, floating, foul-smelling stools, flatulence and meteorism. She also has bone pain and easy bruising. Laboratory studies show anemia with serum iron: 25 mg/dl , ferritin: 25 mg/dl and serum total iron binding capacity 600 mg/dl (normal 300-360 mg/dL); PT is 16 sec. Physical examination shows loss of subcutaneous fat, pallor, hyperkeratosis and abdominal distention; bowel sounds are increased. Which of the following is most likely associated with this patient's condition?

A 12-year-old girl is brought to the clinic due to a 2-month history of headaches. Her headaches last 1-2 hours and have no fixed time of occurrence. She denies nausea, vomiting, chills or fevers. She has no other medical problems and takes no medication. Her family history is significant for hypertension and diabetes. Her blood pressure is 156/90 mm Hg, pulse is 80/min, and respirations are 14/min. Examination shows an alert child in no distress. There is a soft to-and-fro bruit heard at the right costovertebral angle. Which of the following is the most likely cause of her hypertension?

A 13-year-old comes to your office expressing concern about his height. He had first seen you a year prior for his routine checkup and a preparticipation sports physical for soccer (see growth curve). Now in the eighth grade, all of his friends are taller than he is, and he is at a disadvantage on the soccer field playing against much larger boys. After obtaining height information from his parents shown here, you order a skeletal bone age radiograph. Which of the following results would allow you to assure him of an excellent prognosis for normal adult height?

A 12-year-old boy is brought to the emergency department because of severe pain near his left knee. He has sickle cell disease and has been hospitalized previously for sickle cell crisis. Vital signs are notable for persistent fever. Examination of the left lower extremity reveals a normal knee joint with marked tenderness and swelling over the proximal tibia. Laboratory studies show leukocytosis and elevated ESR. Imaging studies confirm the diagnosis of osteomyelitis. Which of the following organisms is the most likely cause of his condition?

A 14-year-old African American male collapses and dies while playing basketball at a school tournament. He has no known past medical history. Which of the following is the most likely underlying disease in this patient?

A 14-year-old African American male is referred to your office after his older brother experienced sudden cardiac arrest during hiking trip. He has no current complaints. He denies any illicit drug use. His blood pressure is 110/60 mmHg and his heat rate is 75/min. Neck is supple, no jugular venous distention is appreciated. Carotid pulse seems to have dual upstroke. Lungs are clear. There is strong apical impulse and a systolic ejection type murmur along the left sternal border. Which of the following is most likely to increase the murmur intensity in this patient?

A 14-year-old boy is brought by his mother because she noticed a change in his voice. He has been having frequent nosebleeds for the last month, and feels that his "left nose" is always congested. There is no history of trauma. He admits to using marijuana, in the absence of his mother. He is otherwise well, and does not take any medications. He actively participates in the school basketball tournaments. Physical examination reveals an intact nasal septum with a visible mass at the back of the left nostril. CT scan reveals an erosion of the adjacent bone. What is the most likely reason of this patient's nosebleeds?

A 14-year-old boy is evaluated for short stature. He has no significant past medical history and is considered otherwise healthy by his parents. He eats a normal diet and has regular meals. His height and weight have been consistently at the 5th percentile since early childhood. His physical examination is normal, with genitalia at Tanner stage 3. Which of the following is the most likely laboratory finding for this boy?

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 stimulating 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?

A 14-year-old girl presents to clinic for an annual check up. Her parents are concerned that the child is not meeting normal milestones of adolescent growth. The patient reports no recent illnesses. She is up-to-date on her vaccines, and is not having any trouble in school. She denies drug use and is active in sports. On examination, her vital signs are stable. Her lungs are clear and heart is regular in rate and rhythm. Breast and areolar enlargement is noted with no contour separation of the areola. Pubic hair is noted to be dark. The patient also reports that she started menstruating 8 months ago. Which of the following is the most likely Tanner stage of development in this patient?

A 14-year-old girl s 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 characters. A urine pregnancy test is negative. Serum prolactin and thyroid stimulating 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?

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?

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?

A 15-year-old female presents to your office with secondary amenorrhea. As part of your evaluation, you find that she is pregnant. After informing her of the pregnancy, you continue to explain that young mothers have a higher risk of several pregnancy-related complications, including which of the following?

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?

A 15-year-old girl is seen in your clinic with a sprained ankle, which occurred the previous day while she was exercising in her room. You realize that you have not seen her for quite some time, and begin to expand your examination beyond the ankle. You find relatively minimal swelling on her right ankle. She has dental decay, especially of anterior teeth and a swollen, reddened, irritated uvula. She seems to be somewhat hirsute on her arms and legs, but has thinning of her hair of the head. She has a resting heart rate of 60 beats per minute, and her oral temperature is 35.5°C (96°F). Further questioning suggests that she has developed secondary amenorrhea. Which of the following is the most appropriate next step in the management of this girl?

A 15-year-old male is brought to the emergency department due to sudden-onset difficulty breathing for the past 45 minutes. He also complains of nausea, colicky abdominal pain and a swollen face. He has been suffering from bronchitis for the past 4 days, and his condition had been improving. His mother says that he had a similar episode when he had a tooth extraction 2 year ago. On examination, there is an edematous swelling of his face including the lips, hands, arms, legs, and genitals. His pulse is 82/min, blood pressure is 120/80 mmHg, respirations are 18/min and temperature is 36.8°C (98.4°F). Which of the following best explains the pathological process of his condition?

A 16-day-old infant presents with fever, irritability, poor feeding, and a bulging fontanelle. Spinal fluid demonstrates gram-positive cocci. Which of the following is the most likely diagnosis?

A 16-year-old African American male with sickle cell anemia presents complaining of a 1-week history of exertional dyspnea, fatigue, and generalized weakness. He denies fevers, chills, night sweats, or cough. His only medication is oxycodone for chronic pain. On physical examination, he weighs 68 kg (150 lbs) and is 168cm (66 in) tall His temperature is 36.7C (98F), blood pressure is 120/70 mm Hg, pulse is 76/min, and respirations are 18/min. All organ systems appear normal Laboratory studies show: Hematocrit 20%, Mean corpuscular volume 110 fl, Reticulocyte count 1.0%. Which of the following is the most likely mechanism underlying these findings?

A 16-year-old Asian boy presents with a two-day history of fever, malaise, and painful enlargement of his parotid glands. He has no significant past medical history. He was born in India, and has not received any childhood vaccinations. He recently returned from a one-week vacation in India. His vital signs are stable, except for a mild fever. Examination shows bilateral parotid enlargement. The rest of the examination is unremarkable. Which of the following organs is most likely to be affected by this patient's illness?

A 16-year-old Asian boy presents with a two-day history of fever, malaise, and painful enlargement of his parotid glands. He has no significant past medical history. He was born in India, and has not received any childhood vaccinations. He recently returned from a one-week vacation in India. His vital signs are stable, except for a mild fever. Examination shows bilateral parotid enlargement. The rest of the examination is unremarkable. Which of the following organs is most likely to be affected by this patient's illness?

A 16-year-old boy is brought into the emergency department by his friends. He is semicomatose, with a pulse of 60/min and respirations of 6-8/min. His pupils are constricted. Which of the following will most likely be revealed on a urine toxicology screen?

A 16-year-old boy presents to the emergency center with a 2-day history of an abscess with spreading cellulitis. While in the emergency center, he develops a high fever, hypotension, and vomiting with diarrhea. On examination you note a diffuse erythematous macular rash, injected conjunctiva and oral mucosa, and a strawberry tongue. He is not as alert as when he first arrived. This rapidly progressive symptom constellation is likely caused by which of the following disease processes?

A 16-year-old boy who is the backup quarterback for the local high school team is in your office complaining of worsening acne. For the last few months he has noted more acne and more oily hair. On his examination, you note gynecomastia and small testicular volume. He is SMR 5. Which of the following drugs of abuse is the likely explanation for all of his findings?

A 16-year-old boy with a history of ulcerative colitis presents to the physician complaining of diarrhea and a rash. He states that his appetite has been decreased recently, and also complains of nausea and abdominal pain in addition to watery diarrhea. He has an erythematous rash on his distal arms and legs that "burns". His mother reports that he has had poor concentration and has been irritable lately. Vital signs are stable. Examination reveals a beefy red tongue that appears swollen. Abdominal examination is normal. The rash resembles a sunburn and is located on his distal arms and legs. It is symmetrical and tender to palpation. Neurological examination is normal. This patient's symptoms are most likely due to a deficiency of which of the following vitamins?

A 16-year-old Caucasian male presents to the office with pain and limited motion of the right knee. His right knee, as well as his right ankle, has swelled several times before. He has a history of easy bruising since childhood, and an episode of excessive bleeding after a tooth extraction. His uncle had similar problems. Which of the following is the most likely cause of this patient's joint pain?

A 16-year-old College student presents to the physician's office because of a generalized 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?

A 16-year-old female complains of headaches and visual impairment for the past month. She says that the headaches are worst in the morning and are associated with nausea. Her medical history is also significant for severe acne for which she takes oral isotretinoin. On physical examination, her temperature is 36.7°C (98°F), blood pressure is 130/80 mm Hg, pulse is 70/min, and respirations are 15/min. She has papilledema and decreased visual acuity. There is no neck stiffness. Motor examination shows 5/5 power, 2+ deep tendon reflexes, and a normal plantar response. Sensory examination is unremarkable. CT scan of the head is within normal limits. Lumbar puncture reveals the following: Opening pressure 250 cm H20, CSF glucose 40 mg/dL, CSF protein 40 mg/dL, WBC 3/mm3. Which of the following is the most likely cause of her symptoms?

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 cell 3/mm3. Which of the following is the most likely cause of this patient’s symptoms?

A 16-year-old girl is in your office for a preparticipation sports examination. She plans 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?

A 16-year-old girl presents with a 2-day history of lower abdominal discomfort, burning micturition and increased frequency of urination. She had her first sexual intercourse last week. Her vital signs are stable. Examination shows suprapubic tenderness. Urinalysis shows positive nitrites, positive esterase, 50+ WBC, and many bacteria. Which of the following is the most likely mechanism responsible for her clinical condition?

A 16-year-old girl presents with a history of primary amenorrhea. On examination, short stature and a short neck with a low posterior hairline are noted. Chromosomal analysis most likely would reveal which of the following?

A 16-year-old girl with an incomplete vaccination record received one dose of the measles, mumps, and rubella (MMR) vaccine during a doctor's visit. One month later, she learns that she is 9 weeks pregnant, and she is concerned about potential birth defects resulting from the MMR vaccine. Which of the following most closely approximates the risk of birth defects secondary to MMR vaccine exposure during the first trimester?

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?

A 17 -year-old boy is brought to the emergency department by his father after the boy began threatening him at home. Over the last several months, the father reports, the boy has been increasingly abusive. He was recently involved in a fist fight at school. The boy states that there is nothing wrong. He is otherwise healthy. He denies alcohol use, but does admit to occasional marijuana use. On examination he has acne on his forehead and back and his hairline is receding. There is palpable tissue underneath his nipples bilaterally Heart and lung exams are normal. What substance is this boy most likely abusing?

A 17-year-old girl develops exertional dyspnea, but has no cough, sputum, or wheezing symptoms. On examination, she has a fixed splitting of her second heart sound and a 3/6 systolic ejection murmur heard best over the left sternal border. An echocardiogram confirms the condition. Which of the following is the best physiologic explanation for her condition?

A 17-year-old girl is seen by her primary care physician for the evaluation of left lower quadrant pain. The physician felt a pelvic mass on physical examination and ordered a pelvic ultrasound. You are consulted because an ovarian neoplasm is identified by the ultrasound. Which of the following is the most common ovarian tumor in this type of patient?

A 17-year-old girl presents to the office with a 5-day history of a malodorous vaginal discharge. She is sexually active and uses condoms for sexual intercourse. On examination, a thin, white discharge is seen. A "fishy" odor is produced when KOH is added to the discharge. The vaginal fluid has a pH of 5. Which of the following is the most likely finding on a microscopic examination of the vaginal fluid?

A 17-year-old male presents to clinic for routine check-up. He is a long distance runner and has beenachieving outstanding results recently. He is very proud of his athletic achievements, remarking that his effort "pays off." He does not smoke or consume alcohol. His family history is significant for diabetes mellitus in his mother and skin cancer in his father. Chest examination is normal. His liver span is 8 cm and his spleen is not palpable. His current laboratory findings include: Hematocrit 59%, WBC count 7,500/mm3, Platelet count 170,000/mm3, ESR 15 mm/hr. Which of the following is the most likely explanation for the high hematocrit in this patient?

A 17-year-old man comes to the emergency department and complains of intensive left flank pain that radiates to the groin. He refers to his symptom as "stone passage," which he has experienced "for so many times since childhood." His uncle has the same problem. Urinalysis shows hexagonal crystals. The urinary cyanide nitroprusside test is positive. Which of the following is the most likely cause of this patient's condition?

A 17-year-old sexually active girl comes to your office complaining of acne that is unresponsive to the usual treatment regimen. Physical examination reveals severe nodulocystic acne of her face, upper chest, and back. You consider prescribing isotretinoin (Accutane), but you are concerned about side effects. Reviewing the literature, you find which of the following to be true about isotretinoin?

A 17-year-old woman, gravida 1, para 0, at 38 weeks' gestation comes to the labor and delivery ward because of contractions. Her dating was determined by a 7-week ultrasound. Her prenatal course was complicated by gestational diabetes. Her past surgical history is significant for shoulder surgery. She takes insulin and prenatal vitamins. She has no known drug allergies. She smokes 3-4 cigarettes per day. She is initially found to be 4 cm dilated and is contracting every 2-3 minutes. She is admitted to the labor and delivery ward and, over the next 4 hours, progresses to full dilation. After pushing for 2 hours, she delivers the fetal head but has great difficulty delivering the fetal shoulders. Eventually, the fetus is delivered by the posterior arm. In the process of delivery of the newborn's humerus is fractured. Which of the following factors contributed the most to the difficult delivery of the fetus?

A 19-year-old college student presents with a testicular mass, and after treatment he returns for regular follow-up visits. Which of the following is the most useful serum marker for detecting recurrent disease after treatment of nonseminomatous testicular cancer?

A 19-year-old football linebacker is admitted following a motor vehicle accident. He had an extensive cerebral bleed, which led to a deep coma. He also has fractures of the C4 vertebra, pelvis, and right femur. Following admission, he is intubated and central lines are placed. During the next few days, he develops acute renal failure due to rhabdomyolysis. While he is recovering from acute renal failure, he is found to have a serum calcium level of 12.1 mg/dL. Other investigations are: Serum albumin 3.0 g/dL, Serum creatinine 2.8 mg/dL, Serum phosphorus 3.8 mg/dL, Blood glucose 108 mg/dL, PTH 9 pg/mL, PTHrP undetectable, 1, 25-dihyroxy vitamin D 19 pg/mL (normal 20-60 kg/mL). What is the most likely cause of this patient's hypercalcemia?

A 19-year-old male has a history of athlete’s foot but is otherwise healthy when he develops sudden onset of fever and pain in the right foot and leg. On physical examination, the foot and leg are fiery red with a welldefined indurated margin that appears to be rapidly advancing. There is tender inguinal lymphadenopathy. The most likely organism to cause this infection is which of the following?

A 19-year-old man sustains multiple injuries in a high-speed automobile collision. There is a pneumothorax on the left, for which he has a chest tube placed. Over the next several days, a large amount of air drains continuously through the tube (a large "air leak"), and daily chest x-rays show that his collapsed left lung is not expanding. The patient is not on a respirator. Which of the following is the most likely cause of these findings?

A 19-year-old man is brought in to the emergency department after being stabbed in the back. He has no past medical history and takes no medications. Muscle strength is absent and tone is decreased in the right leg. The right patellar and Achilles reflexes are absent. Babinski sign is present on the right. There is a loss of vibratory sense and toe joint position on the right. There is a loss of pain and temperature sensation below T12 on the left. Which of the following will cause a loss of pain and temperature sensation on the left side, beginning at T12?

A 19-year-old patient presents to your office with primary amenorrhea. She has normal breast and pubic hair development, but the uterus and vagina are absent. Diagnostic possibilities include which of the following?

A 19-year-old white male presents with nausea, vomiting, and abdominal cramps. He has had four episodes of vomiting over the last two hours. He has not had diarrhea or fever. Four hours ago, he ate a salad from a local restaurant. His pulse is 82/min, blood pressure is 120/80 mm Hg, and temperature is 37.2°C (99°F). Abdominal and rectal examinations are unremarkable. Which of the following is the most likely cause of this patient's symptoms?

A 19-year-old woman comes to the physician because of irregular vaginal bleeding. She has asthma and has never had surgery. She takes albuterol for her asthma and has been taking the oral contraceptive pill for 2 years. She has no allergies to medications. On examination she is found to have a vaginal lesion, which is biopsied. The biopsy shows clear cell adenocarcinoma of the vagina. This patient's malignancy is most likely associated with which of the following types of exposure?

A 19-year-old woman is being treated for Hodgkin's disease that originally presented as a painless, rubbery, enlarged right supraclavicular lymph node. She has recently completed a cycle of chemotherapy protocol that consists of Adriamycin, bleomycin, vinblastine, and dacarbazine (ABVD), and was reported to have tolerated the chemotherapy well. Shortly before her next planned cycle of chemotherapy, however, the patient comes to the emergency department complaining of diffuse abdominal pain and bloating. She has not had a bowel movement in 3 days, though she thinks she is still passing gas. Vital signs at this time are: temperature 37.0 C (98.6 F), blood pressure 128/78 mm Hg, pulse 115/min, and respirations 20/min. Examination reveals a diffusely distended abdomen that is mildly tender to palpation in all four quadrants, without rebound pain or guarding. The supraclavicular mass is not palpable. An abdominal radiograph reveals dilated loops of small bowel with air fluid levels and gas present throughout the colon and rectum. The patient is admitted to the medicine floor for management. Which of the following is the most likely cause of her current condition?

A 19-year-old woman was traveling in a rural area of South America. She returned 3 weeks ago and, over the past few days, has gradually developed lower abdominal pain and diarrhea. Now the symptoms are much worse with 10 stools a day consisting mostly of mucus and blood. She is afebrile, the abdomen is tender in left lower quadrant, and the remaining examination is normal. Her stool is mostly comprised of blood and mucus. Which of the following is the most likely causative organism?

A 2 1/2-year-old child is evaluated by a neurologist because of difficulty walking. Neurological examination documents ataxia and mental retardation. The neurologist notes the presence of multiple telangiectasias involving the conjunctiva, ears, and antecubital fossae. The child also has a history of multiple respiratory tract infections. Immunoglobulin studies on the child would most likely demonstrate an absence of which of the following?

A 2-month-old infant comes to the emergency center with fever for 2 days, emesis, a petechial rash, and increasing lethargy. In the ambulance he had a 3-minute generalized tonic/clonic seizure that was aborted with lorazepam. He does not respond when blood is drawn or when an IV is placed, but he continues to ooze blood from the skin puncture sites. On examination, his anterior fontanelle is open and bulging. His CBC shows a WBC of 30,000 cells/μL with 20% band forms. Which of the infant’s problems listed below is a contraindication to lumbar puncture?

A 2-day-old male infant is jaundiced. He was born at term from an uncomplicated 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?

A 2-month-old male is brought to the emergency department for evaluation of cyanosis, which occurred earlier in the day while the infant was taking his bottle. Initially, he became fussy and sweaty, then his mother noticed that his lips turned blue. He became intermittently tachypneic and continued to cry. As the crying continued, the cyanosis worsened. His temperature is 37C (98.6 F), blood pressure is 80/50 mmHg, pulse is 150/min, and respiratory rate is 45/min. On examination, the child is alert, cyanotic, and tachypneic. Cardiac auscultation reveals a normal S 1 followed by a systolic ejection click. A grade 2/6 crescendo-decrescendo systolic ejection murmur is heard at the left upper sternal border. The patient is immediately placed in a knee-chest position. This maneuver will improve this patient's condition by which of the following mechanisms?

A 2-week-old infant presents with hepatosplenomegaly and a thick, purulent, bloody nasal discharge. Coppery, oval, maculopapular skin lesions are present in an acral distribution. The neurologic examination is normal, including head circumference. Which of the following is the most likely cause of this congenital infection?

A 2-week-old boy in the neonatal intensive care unit had a birth weight of 1200 g. Ultrasound of the head reveals grade II intraventricular hemorrhage and periventricular leukomalacia. An ophthalmologic examination reveals retinopathy of prematurity of both eyes. In addition, a hearing screen demonstrates bilateral hearing deficits. Which of the following is the most important determinant of this child's neurodevelopmental outcome?

A 2-week-old neonate is brought to the office due to poor feeding and persistent vomiting. He had an episode of jerky movements of his limbs this morning. He was delivered at term with no complications and weighed 2.7kg (6 Ib) at birth. He appears lethargic, irritable and jaundiced. On examination, he weighs 2.2kg (5 Ib). His liver and spleen are enlarged. Bilateral cataracts are evident. Which of the following is most consistent with these findings?

A 2-year-old boy is being followed for congenital cytomegalovirus (CMV) infection. He is deaf and developmentally delayed. The child’s mother informs you that she has just become pregnant and is concerned that the new baby will be infected and may develop serious consequences. Which of the following is true?

A 2-year-old boy is brought to the office by his mother because he has not started to walk yet. His birth history is significant for prolonged labor, and his APGAR scores at 1 and 5 minutes were 3 and 5, respectively. His older brother is 4 years old, and has a normal developmental history. On examination, the child has hypotonia, learning disabilities and hyperactive deep tendon reflexes. What is the most likely cause for the child's delayed milestones?

A 2-year-old boy is brought to the office by his parents due to severe diarrhea since yesterday. He has had approximately 20 episodes of non-bloody, non-mucoid stool passage in the last twenty hours, and one episode of bilious vomiting. He is also feeding less than usual. He is febrile, tachycardic and moderately dehydrated. What is the most likely cause of his presentation?

A 2-year-old boy is brought to the pediatrician for a routine well-child visit. He has been growing and developing normally. He is starting to put words together into 2-word phrases. The boy eats a variety of foods including meats, vegetables, and fruits, and drinks 24-28 ounces (700ml) of whole milk each day. Past medical history is unremarkable. His mother has no concerns at today's visit. His physical examination is within normal limits. Laboratory results are as follows: Complete blood count: Hemoglobin 9.4 g/dl, Hematocrit 28%, Mean corpuscular volume 64 fl, Red cell distribution width 14% (normal 11.5%-16.0%), Reticulocytes 3.0%, Platelets 240,000/µL, Leukocytes 7,500/µL, Blood, plasma, and serum, Ferritin 100 ng/ml (7-140 ng/ml), Iron-binding capacity 300 µg/dl (240-450 µg/dl). Which of the following is the most likely cause for this child's anemia?

A 2-year-old boy is rushed to the emergency department by his 21 -year-old white mother because he had a sudden-onset nosebleed which has now subsided. He never had any previous episodes. He is "sickly" and suffers from a productive cough and diarrhea that "refuses to go." His stools are greasy and foul-smelling. His appetite is normal, although his diet consists mainly of milk. His mother's boyfriend lives with them and is a chronic alcoholic. He was delivered vaginally without any complications. His weight is at the 25th percentile for his age. Physical examination reveals dry skin and dried blood at the nasal turbinates. What is the most likely cause of this child's failure to thrive?

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 two common 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?

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?

A 2-year-old child is brought to the emergency department with sudden onset of unresponsiveness, miosis, bradycardia, and muscle fasciculations. These findings are most suggestive of poisoning with which of the following?

A 2-year-old girl has severe dental caries of the upper and lower incisors. Her teeth are brushed twice daily with a small amount of fluoride-containing toothpaste. What is the feeding practice most likely to result in this pattern of dental caries?

A 2-year-old girl is brought to the clinic due to fever, irritability and lethargy for the past two weeks. Over the past two months, she has complained of intermittent abdominal discomfort and has lost weight. Abdominal palpation reveals a firm nodular mass in the right flank. No bruits are heard. Abdominal x-ray reveals multiple calcifications in the renal area. Urine examination reveals increased levels of homovanillic acid and vanillylmandelic acid. Which embryonic structure has this mass most likely arisen from?

A 2-year-old girl presents with fever of 39.3 C and irritability. She has had an upper respiratory tract infection for 4 days. On examination, the right ear is bulging and has poor movement on insufflation. Which of the following organisms is most likely responsible for these findings?

A 20-month-old male is brought to ER with high fever, confusion and a skin rash suggestive of measles. He has a history of recurrent respiratory infections over the last 6 months. The patient's family has recently emigrated from a rural Russian province. Which of the following forms of vitamin supplementation should be considered in this patient?

A 20-year-old Caucasian male presents with lower abdominal pain for the past few hours. The pain first started around the umbilicus, but then shifted to the right lower abdominal area. He has had one episode of vomiting. Physical examination shows tenderness at McBurney's point. CT scan of the abdomen confirms the diagnosis of acute appendicitis. Which of the following explains the pathophysiology of the shifting of pain from the peri-umbilical area to the right lower quadrant in acute appendicitis?

A 20-year-old female with Müllerian agenesis is undergoing laparoscopic appendectomy by a general surgeon. You are consulted intraoperatively because the surgeon sees several lesions in the pelvis suspicious for endometriosis. You should tell the surgeon which of the following?

A 20-year-old G0 and her partner, a 20-year-old man, present for counseling for sexual dysfunction. Prior to their relationship, neither had been sexually active. Both deny any medical problems. In medical experience, which type of male or female sexual dysfunction has the lowest cure rate?

A 20-year-old male university student presents with a one-month history of 4 to 6 loose watery bowel movements per day with occasional tenesmus, urgency, and abdominal cramps. He also describes a two-week history of intermittent bright red blood per rectum. His appetite and energy levels are excellent and his weight is stable. He is otherwise healthy and takes no medications. His family history is unremarkable. He has not recently used antibiotics nor has he traveled outside the country. He does not use tobacco, alcohol or drugs. Sigmoidoscopy demonstrates mild erythema and rectal biopsy confirms acute mucosal inflammation. Which of the following is a potential complication of this condition requiring regular surveillance?

A 20-year-old man is brought to the emergency department by his mother because of a one-day history of fever, headache, and altered mental status. He has no history of medical illness. Herpes simplex encephalitis is suspected after cerebral spinal fluid analysis shows lymphocytic pleocytosis, elevated protein level, and normal glucose level; in addition, CT scan shows contrast enhancement in the temporoparietal area. High-dose intravenous acyclovir therapy is started. Two days after the beginning of the therapy, the neurologic status improves, but the patient develops oliguria. Laboratory studies show: Serum sodium 140 mEq/L, Serum potassium 4.5 mEq/L, Serum creatinine 2.8 mg/dl, BUN 25 mg/dl. Which of the following is the most likely cause of renal damage in this patient?

A 20-year-old woman presents to your office for a well-woman examination. She has been sexually active with one male partner for the past year. She has not achieved orgasm with her partner. On further questioning, she has never achieved orgasm with other partners or with masturbation or the use of a vibrator. Which of the following statements is true regarding her condition?

A 20-year-old woman presents to your office for her well-woman examination. She has recently become sexually active and desires an effective contraceptive method. She has no medical problems, but family history is significant for breast cancer in a maternal aunt at the age of 42. She is worried about getting cancer from taking birth control pills. You discuss with her the risks and benefits of contraceptive pills. You tell her that which of the following neoplasms has been associated with the use of oral contraceptives?

A 21 -year-old male has been experiencing severe headaches for the past week. He also describes difficulty grasping objects in his right hand and difficulty getting dressed, which both started today. CT scan of the head shows a ring-enhancing lesion in the left frontal lobe and a fluid collection in the left maxillary sinus. Tissue biopsy of the brain lesion is most likely to demonstrate which of the following?

A 21-year-old college junior requests an urgent appointment with her family physician to discuss a "personal concern." During her conversation with the doctor, the woman appears tense, speaks very little, and makes minimal eye contact. After gentle questioning, she breaks down and says that her father is taking lithium for a manic episode experienced two years ago. She had not realized this could have any bearing on her own situation until she encountered an article on the Internet that mentioned genetics appears to play a role in the pathogenesis of bipolar disorder. Since then, she has had disturbed sleep and has been very worried that she too will one day develop bipolar disorder. Based on clinical data, what is the likelihood that she will have a manic episode during her lifetime?

A 21-year-old G0 woman presents for a well-woman examination. Menarche began at age 12 years, and her periods occur every 26–30 days and last 4–5 days. She has had two sexual partners since becoming sexually active last year. She uses condoms for contraception and denies a history of sexually transmitted disease. Her physical examination is within normal limits. She has never had a pelvic exam before, and asks why it is necessary for her to get a Pap smear. Which of the following statements about cervical cancer screening is true?

A 21-year-old nulligravid woman comes to her physician to discuss birth control options. She became sexually active for the first time 2 weeks ago. She is currently using condoms for contraception. Her past medical history is significant for asthma, which has been inactive for 2 years. She takes no medications and has no allergies to medications. She has no family history of cancer. Her examination is within normal limits. After a discussion with the physician, she chooses to take the oral contraceptive pill (OCP). She stays on the pill for the next 6 years. She now has most significantly decreased her risk of developing which of the following malignancies?

A 21-year-old woman presents to the ED complaining of diarrhea, abdominal cramps, fever, anorexia, and weight loss for 3 days. Her BP is 127/75 mm Hg, HR is 91 beats per minute, and temperature is 100.8°F. Her abdomen is soft and nontender without rebound or guarding. WBC is 9200/μL, β-hCG is negative, urinalysis is unremarkable, and stool is guaiac positive. She tells you that she has had this similar presentation four times over the past 2 months. Which of the following extraintestinal manifestations is associated with Crohn disease but not ulcerative colitis?

A 21-year-old woman presents with left lower quadrant pain. An anterior 7-cm firm adnexal cyst is palpated. Ultrasound confirms a complex left adnexal mass with solid components that appear to contain bone and teeth. What percentage of these tumors are bilateral?

A 21-year-old woman returns to your office for evaluation of an abnormal Pap smear. The Pap smear showed a squamous abnormality suggestive of a high-grade squamous intraepithelial lesion (HGSIL). Colposcopy confirms the presence of a cervical lesion consistent with severe cervical dysplasia (CIN III). Which of the following human papilloma virus (HPV) types is most often associated with this type of lesion?

A 21-year-old woman visits her physician because of 3 weeks of a flu-likeǁ illness. She reports symptoms of malaise, fever, fatigue, and a sore throat. There is no weight loss or night sweats, and she has not traveled out of country. Her past medical history is not significant and she is not taking any medications. Physical examination is normal except for enlarged cervical lymph nodes. Laboratory data show hemoglobin 13.2 g/dL; hematocrit 42%; platelets 380,000/mL; WBC 8500/mL, with 35% segmented neutrophils, 1% eosinophils, and 64% lymphocytes, of which 36% were atypical. A heterophil antibody (sheep cell agglutination) test is negative. Which of the following is the most likely causative organism?

A 22-year-old African-American man presents to the ER with fever, jaundice, abdominal pain, and dark urine. His heart rate is 100/min and blood pressure is 100/60 mmHg. Peripheral blood smear reveals bite cells and red blood cell inclusions seen after crystal violet staining. The patient most likely suffers from which of the following conditions?

A 22-year-old Caucasian female who has received no prenatal care experiences a stillbirth. This is her first pregnancy. The baby has multiple fractures, blue sclerae and short, bent extremities. Her past medical history is significant for a seizure disorder. She has been taking phenytoin regularly and had no seizure episodes during the pregnancy. She admits to eating poorly and occasionally drinking alcohol during the first trimester. She lives with her boyfriend who abuses her physically. She recalls several episodes of abuse during the pregnancy. Which of the following is most likely responsible for fetal abnormalities?

A 22-year-old college student went to the health clinic complaining of a fever over the last 5 days, fatigue, myalgias, and a bout of vomiting and diarrhea. The clinic doctor diagnosed him with acute gastroenteritis and told him to drink more fluids. Three days later, the student presents to the ED complaining of substernal chest pain that is constant. He also feels short of breath. His temperature is 100.9°F, HR is 119 beats per minute, BP is 120/75 mmHg, and RR is 18 breaths per minute. An ECG is performed revealing sinus tachycardia. A chest radiograph is unremarkable. Laboratory tests are normal except for slightly elevated WBCs. Which of the following is the most common cause of this patient’s diagnosis?

A 22-year-old female is hospitalized after a car accident. She sustained a hip fracture, fractures of several ribs and a blunt abdominal injury that required a laparotomy. The laparotomy revealed a liver laceration and extensive hemoperitoneum. In the early postoperative period, the patient is noted to have hyperactive deep tendon reflexes. Which of the following electrolyte abnormalities may be responsible for this condition?

A 22-year-old female presents to the emergency room with a nosebleed. A quick review of her records reveals that she presented with the same problem yesterday, at which time the bleeding was stopped with prolonged local pressure. On review of systems, the patient also reports easy bruising for the past several months. On physical examination, her heart and lungs appear normal. The liver span is 8 cm and the spleen is not palpable. There are scattered ecchymoses over her arms and legs. Laboratory findings include the following: Hematocrit 45%, Platelet count 9,000/mm3, Leukocyte count 5,500/mm3, Neutrophils 56%, Eosinophils 1%, Lymphocytes 33%, Monocytes 10%, Fibrinogen 250 mg/dL, Prothrombin time 13 sec. Which of the following is the most likely cause of this patient's condition?

A 22-year-old G1 at 14 weeks gestation presents to your office with a history of recent exposure to her 3-year-old nephew who had a rubella viral infection. In which time period does maternal infection with rubella virus carry the greatest risk for congenital rubella syndrome in the fetus?