Surgery MCQs Q9

A male infant presents with poor urinary stream and recurrent urinary tract infections. On examination, there is bladder distension and palpable kidneys.

Which of the following is the investigation of choice for posterior urethral valves (PUV)?

A. Micturating cystourethrogram (MCU)

B. Cystoscopy

C. Cystourethroscopy

D. Retrograde ureteroscopy

E. CT scan

✅ Correct Answer:

A. Micturating cystourethrogram (MCU)

Explanation of Correct Answer

MCU (Voiding cystourethrogram) is the gold standard investigation for diagnosing posterior urethral valves. It allows for:

• Visualization of the posterior urethra during voiding.
• Assessment of bladder changes (thickening, trabeculations).
• Detection of vesicoureteral reflux (VUR).

Explanation of Wrong Options

B. Cystoscopy: Can directly visualize valves but is invasive, usually reserved for definitive treatment (valve ablation), not initial diagnosis.

C. Cystourethroscopy: Essentially same as cystoscopy; useful therapeutically but not first-line diagnostic tool in infants.

D. Retrograde ureteroscopy: Investigates ureters and renal pelvis, not suitable for detecting posterior urethral valves.

E. CT scan: May detect hydronephrosis or renal abnormalities, but cannot reliably visualize valves.

🧠 High-Yield Points

Posterior urethral valves: Most common cause of lower urinary tract obstruction in male infants.
Key initial investigation: MCU / VCUG.
Clinical features: Poor urinary stream, UTI, palpable bladder/kidneys, failure to thrive.
Definitive treatment: Endoscopic valve ablation.

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💡 Quick Clinical Challenge:

An antenatal ultrasound reveals bilateral hydronephrosis and a "keyhole sign" in a male fetus.

Your Challenge:

1. What does the "keyhole sign" represent on ultrasound?
2. What is the most concerning complication of PUV in the neonatal period?

Show Answer

✅ Answer:

1. The dilated posterior urethra and distended bladder.
2. Pulmonary hypoplasia due to severe oligohydramnios.