A 6-month-old boy presents with poor urinary stream, recurrent urinary tract infections, and failure to thrive. Renal ultrasound shows bilateral hydronephrosis and a thick-walled, trabeculated bladder. Which investigation is most definitive for diagnosis?

• A DMSA renal scan
• B Micturating cystourethrogram (MCUG/VCUG) ✓
• C Diuretic renogram (DTPA/MAG3)
• D CT urography

Explanation

The clinical picture (poor stream, bilateral hydronephrosis, thick-walled bladder in a male infant) is classic for posterior urethral valves (PUV). MCUG/VCUG is the gold standard, demonstrating the dilated posterior urethra with a narrow jet and vesicoureteral reflux. DMSA shows scarring but not anatomy. Diuretic renogram assesses drainage, not the obstructing lesion. CT involves radiation and does not visualize the valves as well.

Reference: Bailey and Love Short Practice of Surgery, 28th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.