A male neonate develops respiratory distress and ascites shortly after birth. Antenatal scans showed bilateral hydronephrosis and oligohydramnios. Examination reveals a distended bladder and weak urinary stream. Which single investigation will best confirm the underlying cause?

• A Retrograde urethrography
• B Renal dynamic scan (DTPA)
• C Voiding cystourethrogram ✓
• D Urodynamic study

Explanation

The presentation is classic for posterior urethral valves, the commonest cause of lower urinary tract obstruction in male infants, presenting with hydronephrosis, oligohydramnios, pulmonary hypoplasia and urinary ascites. C voiding cystourethrogram demonstrates the dilated posterior urethra with an abrupt transition at the level of the valves, the key diagnostic finding. C DTPA scan assesses function but cannot show the obstructing membranes, and urodynamics is impractical and unnecessary when the anatomical diagnosis is visible on VCUG.

Reference: Campbell-Walsh Urology, 12th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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