Surgery MCQs Q9

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PEDIATRIC SURGERY • RADIOLOGY

A 2-year-old boy presents with poor urinary stream, recurrent urinary tract infections, and abdominal distension. Ultrasound shows bilateral hydronephrosis and a distended bladder with thickened wall. Posterior urethral valves are suspected.

What is the investigation of choice to confirm the diagnosis?

A MCUG (Micturating Cystourethrogram)

B Cystoscopy

C Cystourethroscopy

D Retrograde ureteroscopy

E CT scan

MCUG (Micturating Cystourethrogram). This is the gold standard for confirming Posterior Urethral Valves (PUV). It allows visualization of the dilated posterior urethra and the obstructive valve during the voiding phase.

Decoding Clue

1

CLUE "Male child + obstructive urinary symptoms + hydronephrosis"

TRANS Diagnosis is Posterior Urethral Valves (PUV).

2

CLUE "Investigation of choice to confirm"

TRANS Needs a dynamic study to see the urethra while voiding.

Explanation

A. MCUG: Correct. It shows the hallmark "keyhole" or "spinning top" sign (dilated posterior urethra) and helps identify associated Vesicoureteral Reflux (VUR).

B & C. Cystoscopy/Cystourethroscopy: These are endoscopic procedures. While they can confirm valves, they are invasive and typically reserved for treatment (valve ablation) after the diagnosis is made via MCUG.

D. Retrograde ureteroscopy: Evaluates the ureters and kidneys from below; not useful for identifying a defect in the urethra.

E. CT scan: Provides poor detail of the urethra and involves unnecessary radiation for a child; Ultrasound is the screening tool of choice, MCUG is the confirmatory one.

🧠 High-Yield Pearls

Step	Action / Finding	Reasoning
Initial Screen	Ultrasound KUB	Non-invasive; shows Hydronephrosis & thick bladder
Confirm Diagnosis	MCUG / VCUG	Gold Standard; shows dilated posterior urethra
Immediate Care	Catheterization	Decompress the bladder & stabilize electrolytes
Definitive Tx	Endoscopic Ablation	Surgical removal of the valve leaflets

Integrated Clinical Questions

1. Most common cause of bladder outlet obstruction in male infants?

Answer: Posterior Urethral Valves (PUV).

2. What is the 'Keyhole Sign' on prenatal ultrasound?

Answer: A dilated bladder and dilated posterior urethra appearing like a keyhole, highly suggestive of PUV.

3. Why is PUV a medical emergency in a neonate?

Answer: Severe obstruction can cause pulmonary hypoplasia (due to oligohydramnios) and progressive renal failure.

4. Long-term complication of PUV even after successful surgery?

Answer: Chronic Kidney Disease (CKD) or 'Valve Bladder Syndrome' (myogenic bladder failure).

⚡ Exam Pearls

• MCUG = Diagnosis. Cystoscopy = Treatment.
• Classic triad: Male infant + Distended bladder + Poor stream.
• Associated with bilateral Hydroureteronephrosis.
• Rule of Thumb: Male child + UTI = Think PUV until proven otherwise.

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