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Quizzes > Health & Medicine

Nephrectasis Quiz: Distension of the Kidney

Quick, free quiz to test your knowledge of the medical term for kidney distension. Instant results.

Editorial: Review CompletedCreated By: Frosted MishaUpdated Aug 28, 2025
Difficulty: Moderate
2-5mins
Learning OutcomesCheat Sheet
Paper art kidneys and bladder illustration on coral background quiz on urinary system nephrectasis scanty urine.

This nephrectasis quiz helps you review the distension of the kidney, key definitions, and how to spot related terms on exams. Build recall with quick questions, then deepen context with the renal pelvis anatomy quiz and compare symptoms in the kidney stone or uti quiz. Learn at your own pace with clear feedback on each item.

What does the term 'nephrectasis' refer to?
Inflammation of the kidney
Surgical removal of the kidney
Dilation of the kidney
Formation of kidney stones
The suffix 'ectasis' means expansion or dilation, and 'nephro' refers to the kidney, thus nephrectasis means dilation of the kidney's collecting system due to backpressure. This term is synonymous with hydronephrosis in clinical practice.
Which part of the kidney is primarily dilated in nephrectasis?
Collecting duct
Loop of Henle
Glomerulus
Renal pelvis
Nephrectasis is characterized by dilation of the renal pelvis and calyces due to urine accumulation from obstructed outflow. The pelvis is the funnel-shaped area that collects urine before it passes into the ureter.
Which imaging modality is first-line to detect kidney distension?
CT scan
Intravenous pyelogram (IVP)
Ultrasound
MRI
Ultrasound is noninvasive, readily available, and highly sensitive for detecting dilation of the pelvicalyceal system seen in nephrectasis. It can show echo-free areas in the collecting system with thinning of the renal cortex.
Hydronephrosis is also known as what?
Nephrectasis
Polycystic kidney disease
Glomerulonephritis
Renal agenesis
Hydronephrosis refers to swelling of the kidney due to a build-up of urine, which is synonymous with the term nephrectasis - 'nephro' meaning kidney and 'ectasis' meaning dilation.
Which is a common symptom of kidney distension?
Vision loss
Flank pain
Headache
Cough
Flank pain is the most frequent symptom of hydronephrosis or nephrectasis, resulting from stretching of the renal capsule due to urine accumulation. Other systemic signs are less directly associated.
Scanty urine production is called what?
Anuria
Polyuria
Oliguria
Dysuria
Oliguria is defined as diminished urine output, typically less than 400 mL per day in adults. Anuria refers to near absence of urine (<100 mL/day), polyuria to excessive urine, and dysuria to painful urination.
Oliguria is defined as urine output of less than how many milliliters per day?
800 mL
400 mL
2000 mL
2500 mL
Oliguria is typically defined as daily urine output below 400 mL in adults. This reflects reduced renal excretory function and may accompany obstructive uropathy.
Anuria refers to urine output below what threshold per day?
400 mL
800 mL
100 mL
1000 mL
Anuria is the absence or near absence of urine production, usually defined as urine output below 100 mL per day. It indicates severe renal dysfunction or complete urinary tract obstruction.
The suffix 'ectasis' means what?
Inflammation
Necrosis
Removal
Dilation
The suffix 'ectasis' denotes dilation or expansion of a tubular structure. In nephrectasis or bronchiectasis, it describes abnormal widening of the affected organ.
The prefix 'nephro-' refers to which organ?
Kidney
Bladder
Pancreas
Liver
The prefix 'nephro-' is derived from Greek and refers to the kidney, as seen in nephrology (study of kidneys) and nephrectomy (surgical removal of a kidney).
The pelvicalyceal system includes which structures?
Renal pelvis and calyces
Glomeruli
Proximal tubules
Loop of Henle segments
The pelvicalyceal system is the internal urinary collecting system of the kidney comprising the renal pelvis and its minor and major calyces, which funnel urine into the ureter.
What is the normal adult daily urine output?
800 - 2000 mL
100 - 400 mL
200 - 500 mL
3000 - 4000 mL
Healthy adult kidneys typically produce between 800 and 2000 mL of urine per day, depending on fluid intake and other physiological factors. Outputs below or above this range may indicate pathology.
The primary function of the renal pelvis is to what?
Collect urine from the calyces
Reabsorb sodium
Filter blood plasma
Produce erythropoietin
The renal pelvis acts as a funnel-like reservoir that collects urine from the calyces and directs it into the ureter for transport to the bladder.
In which condition is backpressure the main cause of nephrectasis?
Acute glomerulonephritis
Renal artery stenosis
Obstructive uropathy
Nephrotic syndrome
Obstructive uropathy, such as from stones or strictures, causes urine to back up into the kidney, increasing hydrostatic pressure and leading to dilation of the pelvicalyceal system (nephrectasis).
The abbreviation 'USG' in renal imaging stands for what?
Ureteroscopy guide
Ultrasonography
Urodynamic study
Urography series
USG stands for ultrasonography, a noninvasive imaging method that uses sound waves to visualize internal organs, including the kidneys and urinary tract.
Which one is NOT typically a cause of urinary tract obstruction?
Bladder tumor
Ureteral stones
Dehydration
Ureteral stricture
Dehydration reduces urine production but does not mechanically obstruct flow. Stones, tumors, and strictures physically block urinary passage leading to hydronephrosis.
The most common cause of unilateral hydronephrosis in adults is which condition?
Vesicoureteral reflux
Pregnancy
Benign prostatic hyperplasia
Ureteric stone
Ureteric stones frequently lodge in the ureter causing unilateral obstruction and hydronephrosis. BPH is more often bilateral and lower tract, while reflux and pregnancy affect different demographics.
Vesicoureteral reflux predisposes a patient to which renal finding?
Hydronephrosis
Polycystic kidneys
Glomerulonephritis
Renal artery stenosis
Vesicoureteral reflux allows urine to flow backward from the bladder into the ureters and kidneys, leading to dilation of the pelvicalyceal system (hydronephrosis).
Which congenital anomaly causes posterior urethral valves leading to hydronephrosis in males?
Horseshoe kidney
Posterior urethral valves
Polycystic kidney disease
Ureterocele
Posterior urethral valves are membranous folds in the male urethra that obstruct urinary outflow, causing bilateral hydronephrosis in infants and young boys.
On renal ultrasound, which finding is indicative of hydronephrosis?
Increased cortical echogenicity without dilation
Central echo-free area in the kidney
Absent renal pelvis
Diffuse cortical calcifications
An echo-free (anechoic) area in the central kidney corresponds to fluid-filled dilated pelvicalyceal system seen in hydronephrosis, unlike parenchymal changes which affect echogenicity rather than central fluid.
A diuretic renogram (Lasix renogram) is primarily used to distinguish what?
Glomerular from tubular disease
Acute from chronic renal failure
Obstructive vs non-obstructive hydronephrosis
Pyelonephritis from cystitis
Diuretic renography uses a loop diuretic to assess washout of radiotracer from the kidney; delayed clearance suggests true obstruction, while prompt clearance rules out obstruction despite dilation.
During physical exam, hydronephrosis may present with which palpable finding?
Pulsatile abdominal mass
Costovertebral angle lump
Flank mass
Suprapubic fullness
A significantly distended kidney may present as a palpable flank mass. A pulsatile mass suggests aneurysm and suprapubic fullness suggests bladder distension.
Azotemia refers to an elevation of what laboratory parameters?
Serum albumin and bilirubin
Serum potassium and phosphate
Complete blood count
Blood urea nitrogen and creatinine
Azotemia is characterized by an accumulation of nitrogenous waste products, chiefly blood urea nitrogen (BUN) and creatinine, due to reduced renal clearance.
Which laboratory test is most useful in assessing renal excretory function?
Alanine transaminase (ALT)
Serum amylase
Prothrombin time
Serum creatinine
Serum creatinine is produced by muscle metabolism and is excreted by the kidneys; elevated levels indicate impaired glomerular filtration rate.
Functional obstruction of the kidney can best be evaluated by which method?
Blood pressure monitoring
Plain abdominal X-ray
Diuretic renography
Serum electrolytes
Diuretic renography differentiates between obstructive and non-obstructive dilation by evaluating tracer clearance after diuretic administration, identifying functional blockage.
A DTPA renal scan primarily measures which renal parameter?
Tubular secretion rate
Glomerular filtration rate
Collecting system pressure
Renal blood flow
Technetium-99m DTPA (diethylenetriamine pentaacetate) is filtered solely by the glomerulus, allowing accurate assessment of glomerular filtration rate in each kidney.
Ureteropelvic junction obstruction typically presents on imaging with which feature?
Non-dilated collecting system
Pelvic dilation without ureteral dilation
Isolated ureteral dilation
Diffuse cortical cysts
UPJ obstruction causes dilation of the renal pelvis and calyces, but the ureter remains normal in caliber distal to the junction. This pattern is diagnostic on imaging.
Physiologic hydronephrosis in pregnancy is mainly due to what factor?
Progesterone-mediated ureteral relaxation
Estrogen-induced kidney growth
Increased fetal movement
Elevated aldosterone
High levels of progesterone cause smooth muscle relaxation, leading to dilation of the ureters and renal pelvis, which is physiologic in many pregnant women.
Benign prostatic hyperplasia is a risk factor for which type of urinary obstruction?
Glomerular obstruction
Bladder neck spasm without obstruction
Lower urinary tract obstruction leading to hydronephrosis
Renal artery obstruction
Enlargement of the prostate can compress the urethra and bladder outlet, causing backpressure and secondary hydronephrosis if severe.
Which imaging modality provides the highest anatomic detail for hydronephrosis assessment?
Intravenous pyelogram (IVP)
Plain abdominal X-ray
Nuclear renogram
CT urography
CT urography gives high-resolution cross-sectional images and can evaluate both the collecting system and surrounding structures, making it superior for detailed anatomical assessment.
Which of the following is NOT a recognized grading system for hydronephrosis?
Atmanspacher score
Society for Fetal Urology (SFU)
London classification
Onen grading system
The London classification is not a standard grading system for hydronephrosis. Commonly used systems include the SFU and Onen scales for pediatric and fetal hydronephrosis.
On Doppler ultrasound, a resistive index (RI) above what value suggests obstruction?
0.6 or less
>0.7
0.3
<0.5
An RI greater than 0.7 on intrarenal Doppler ultrasound suggests increased vascular resistance, commonly seen in obstructive uropathy and intrinsic renal disease.
Society for Fetal Urology (SFU) grade I hydronephrosis indicates which ultrasound finding?
Perirenal fluid collection
Marked cortical thinning
Gross pelvicalyceal dilation
Mild splitting of the central renal echo complex
SFU grade I hydronephrosis is the mildest form, showing only slight separation of the central echo (renal pelvis) without calyceal dilation or parenchymal thinning.
In SFU grade III hydronephrosis, ultrasound shows:
Severe cortical scarring
Pelvic and calyceal dilation with mild parenchymal thinning
No dilation of calyces
Perinephric hemorrhage
SFU grade III is defined by dilation of both the renal pelvis and calyces along with mild thinning of the renal cortex.
On a MAG3 renogram, a T1/2 greater than how many minutes suggests obstruction?
10 minutes
30 minutes
20 minutes
5 minutes
A half-time (T1/2) of tracer clearance exceeding 20 minutes on a diuretic renogram is indicative of significant obstruction.
Chronic obstructive nephropathy histologically demonstrates which change?
Medullary calcifications
Acute tubular necrosis
Glomerular hypercellularity
Tubulointerstitial fibrosis
Long-standing obstruction leads to decreased blood flow, ischemia, and eventual tubulointerstitial fibrosis, reducing functional renal parenchyma.
Malacoplakia of the kidney is characterized by which histologic finding?
Glomerular crescents
Amyloid deposits
Michaelis - Gutmann bodies
Xanthoma cells
Malacoplakia features pathognomonic Michaelis - Gutmann bodies, which are laminated mineralized inclusions in macrophages, often in the setting of chronic infection.
Which cytokine is notably upregulated in obstructive nephropathy promoting fibrosis?
IL-2
Erythropoietin
TGF-? (transforming growth factor beta)
TNF-? only
TGF-? is a central mediator in renal fibrogenesis, driving extracellular matrix deposition in response to sustained obstruction.
Post-obstructive diuresis is primarily due to which mechanism?
Natriuresis and osmotic diuresis from accumulated solutes
Elevated ADH release
Increased aldosterone secretion
Decreased cardiac output
After relief of ureteral obstruction, accumulated solutes and water in the kidney cause a diuretic phase due to osmotic and natriuretic diuresis until homeostasis is restored.
A renal resistive index above 0.7 on Doppler ultrasound suggests what?
Acute myocardial infarction
Elevated intrarenal vascular resistance such as in obstruction
Chronic liver disease
Normal renal perfusion
An intrarenal resistive index (RI) >0.7 indicates increased arterial resistance, commonly seen in obstructive uropathy or intrinsic renal parenchymal disease.
On CT urography, hydronephrosis appears as which feature?
Low-attenuation fluid within a dilated collecting system
Diffuse cortical enhancement
High-attenuation calcifications only
Solid renal masses
Fluid in a dilated collecting system shows low attenuation on CT, distinguishing hydronephrosis from solid tissue or calcifications.
On MRI, dilated renal calyces in hydronephrosis are which signal intensity on T2-weighted images?
No signal
Hyperintense (bright)
Hypointense (dark)
Isointense to liver
Fluid appears bright (hyperintense) on T2-weighted MRI sequences, so urine-filled dilated calyces are clearly visible against the darker renal parenchyma.
The 'bear paw' sign on imaging is associated with which renal condition?
Acute glomerulonephritis
Hydronephrosis only
Simple renal cysts
Xanthogranulomatous pyelonephritis
Xanthogranulomatous pyelonephritis shows multiple low-attenuation areas in an enlarged kidney resembling a 'bear paw', reflecting lipid-laden macrophages and abscess cavities.
Renal functional recovery after relief of obstruction depends primarily on what factor?
Serum albumin level
Duration of obstruction
Patient height
Blood type
Prolonged obstruction causes irreversible tubular and interstitial damage; shorter duration obstructions allow for better recovery of renal function after relief.
The Anderson-Hynes pyeloplasty is a surgical procedure used to correct which condition?
Renal artery stenosis
Bladder neck obstruction
Ureteropelvic junction obstruction
Posterior urethral valves
Anderson-Hynes dismembered pyeloplasty reconstructs the ureteropelvic junction to relieve obstruction, commonly performed via open or laparoscopic approaches.
Endopyelotomy is best described as what?
Extracorporeal shock wave lithotripsy
Endoscopic incision of a stenotic ureteropelvic junction
Open removal of kidney stones
Renal biopsy technique
Endopyelotomy involves endoscopic cutting of stenotic tissue at the ureteropelvic junction to relieve obstruction without full open surgery.
A preserved renal function on imaging is suggested if cortical thickness exceeds what measurement?
5 mm
20 mm
1 mm
15 mm
A cortical thickness greater than 5 mm on ultrasound or CT is associated with preserved renal parenchymal function despite dilation.
Which SFU grade of hydronephrosis in adults typically warrants surgical intervention?
Grade II
Grade IV
Grade I
Grade III
SFU grade IV hydronephrosis shows severe dilation of the pelvicalyceal system with cortical thinning, often indicating significant obstruction requiring surgical correction.
RAAS (renin-angiotensin-aldosterone system) activation in obstructive nephropathy primarily promotes which process?
Suppression of TGF-?
Immediate diuresis
Glomerular hyperfiltration
Interstitial fibrosis through angiotensin II signaling
Angiotensin II generated by RAAS stimulates profibrotic pathways including TGF-? production, leading to renal interstitial fibrosis in chronic obstructive nephropathy.
In a renal transplant, a pelvicalyceal diameter greater than what on ultrasound suggests possible obstruction?
5 mm
15 mm
20 mm
10 mm
Post-transplant hydronephrosis with a pelvicalyceal diameter exceeding 10 mm raises concern for obstruction at the ureterovesical anastomosis and warrants further evaluation.
In malignant ureteric obstruction, percutaneous nephrostomy compared to ureteral stent placement generally results in which outcome?
Lower complication rate
Immediate decompression but higher infection risk
Better long-term patency
No need for further interventions
Percutaneous nephrostomy provides rapid relief of obstruction even in complex or malignant cases but carries a higher risk of infection and external catheter complications compared to internal stenting.
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Study Outcomes

  1. Define distension of the kidney (nephrectasis) -

    Provide the clinical definition of nephrectasis and describe the pathophysiological changes that lead to renal distension.

  2. Interpret the medical term scanty urination -

    Explain scanty urination as a condition of scanty urine production and recognize its common etiologies.

  3. Differentiate nephrectasis from other urinary disorders -

    Compare and contrast the clinical features and diagnostic criteria of kidney distension with other urinary system conditions.

  4. Identify clinical symptoms associated with nephrectasis and scanty urination -

    List key signs and symptoms to monitor in patients presenting with renal distension and reduced urine output.

  5. Apply knowledge to quiz scenarios -

    Use your understanding of nephrectasis and the condition of scanty urine production to answer quiz questions accurately and reinforce diagnostic skills.

Cheat Sheet

  1. Definition of Nephrectasis -

    Nephrectasis describes the distension of the kidney's collecting system due to urine backflow, highlighting "nephr - " (kidney) and " - ectasis" (expansion) (Merck Manual). This term clarifies that the distension of the kidney is called nephrectasis, distinct from simple swelling.

  2. Common Obstructive Causes -

    Ureteral stones, strictures, and benign prostatic hyperplasia frequently trigger nephrectasis by blocking urine outflow (American Urological Association). Early identification of these etiologies is vital to prevent irreversible renal damage.

  3. Diagnostic Imaging Strategies -

    Renal ultrasound is the first-line tool for detecting dilation of the collecting system, with high sensitivity for early nephrectasis (American Institute of Ultrasound in Medicine). When ultrasound findings are inconclusive, CT urography offers detailed anatomical resolution.

  4. Medical Term for Scanty Urination -

    Scanty urination, the medical term scanty urination is "oliguria," defined as a condition of scanty urine production below 400 mL per 24 hours (National Kidney Foundation). Oliguria signals compromised renal perfusion or injury and warrants prompt evaluation.

  5. Mnemonic for Urine Output Disorders -

    Remember "AnOliPo" to differentiate Anuria (≤50 mL), Oliguria (<400 mL), and Polyuria (>2,500 mL) in 24 hours (UpToDate). This quick mnemonic helps you recall a condition of scanty urine production and plan appropriate management.

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