Question:medium
In a male fetus, ultrasonography identification of bilateral hydronephrosis and bladder dilatation is diagnostic of
In a male fetus, ultrasonography identification of bilateral hydronephrosis and bladder dilatation is diagnostic of
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Bilateral hydronephrosis plus a dilated bladder in a male fetus points to a urethral outflow obstruction.
Updated On: Jul 7, 2026
- Polycystic kidney disease
- Multicystic dysplastic kidney
- Uteropelvic junction obstruction
- Posterior urethral valve syndrome
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The Correct Option is D
Solution and Explanation
Step 1: Understanding the Concept:
The question gives a pattern rather than a single finding, a big bladder plus both kidneys swollen with urine, and asks which disease explains that whole pattern in a male fetus.
Step 2: Key Approach:
Work from the bladder backward. If the bladder itself is enlarged, the block is most likely downstream at the level of the urethra, since a block higher up at the kidney or ureter would not usually make the bladder itself swell.
Step 3: Detailed Explanation:
A valve like fold in the posterior urethra, found only in male fetuses, obstructs the outlet of the bladder. Urine cannot escape normally, so the bladder swells and thickens first, then pressure travels back up both ureters and both kidneys, causing hydronephrosis on both sides. This combination of thick, large bladder and bilateral hydronephrosis is the signature of posterior urethral valve syndrome.
Polycystic kidney disease and multicystic dysplastic kidney are both primary kidney problems, cysts replacing kidney tissue, and neither one causes the bladder itself to swell. Uteropelvic junction obstruction blocks urine only where the kidney drains into the ureter, almost always on one side, and again spares the bladder.
Step 4: Final Answer:
Only posterior urethral valve syndrome explains both a dilated bladder and bilateral hydronephrosis in a male fetus.
The question gives a pattern rather than a single finding, a big bladder plus both kidneys swollen with urine, and asks which disease explains that whole pattern in a male fetus.
Step 2: Key Approach:
Work from the bladder backward. If the bladder itself is enlarged, the block is most likely downstream at the level of the urethra, since a block higher up at the kidney or ureter would not usually make the bladder itself swell.
Step 3: Detailed Explanation:
A valve like fold in the posterior urethra, found only in male fetuses, obstructs the outlet of the bladder. Urine cannot escape normally, so the bladder swells and thickens first, then pressure travels back up both ureters and both kidneys, causing hydronephrosis on both sides. This combination of thick, large bladder and bilateral hydronephrosis is the signature of posterior urethral valve syndrome.
Polycystic kidney disease and multicystic dysplastic kidney are both primary kidney problems, cysts replacing kidney tissue, and neither one causes the bladder itself to swell. Uteropelvic junction obstruction blocks urine only where the kidney drains into the ureter, almost always on one side, and again spares the bladder.
Step 4: Final Answer:
Only posterior urethral valve syndrome explains both a dilated bladder and bilateral hydronephrosis in a male fetus.
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