Pediatric Urology
Paediatric urology questions centre on antenatal hydronephrosis, vesicoureteric reflux, obstructed systems, undescended testis and the acute scrotum, plus hypospadias. The exam rewards correct timing of surgery and recognition of the few true emergencies.
Antenatal hydronephrosis and posterior urethral valves
- Grade with the SFU system and measure anterior-posterior renal pelvis diameter; below 10 mm in the third trimester is usually benign and needs postnatal ultrasound only.
- Postnatal ultrasound after the first week, when dehydration is corrected; MAG3 renography at around 3 months assesses drainage and split function; VCUG is indicated for bilateral dilatation, duplex systems, thick-walled bladder or suspected valves.
- Posterior urethral valves occur only in boys: bilateral hydronephrosis, thick trabeculated bladder, poor stream, keyhole sign on VCUG. Pass a urethral catheter immediately, check creatinine and potassium, then ablate valves; long-term risk is chronic kidney disease and bladder dysfunction.
Vesicoureteric reflux and urinary infection
- Grade I-V on VCUG; DMSA identifies cortical scarring. Address bladder and bowel dysfunction and constipation first.
- Continuous antibiotic prophylaxis for grade III-V or recurrent febrile infection; options are endoscopic bulking injection and ureteric reimplantation (Cohen or Lich-Gregoir).
- A febrile urinary tract infection in an infant warrants ultrasound and either VCUG or DMSA.
Undescended testis, hypospadias and acute scrotum
- Orchidopexy by 6-18 months, ideally 6-12, to reduce infertility and malignancy risk and allow surveillance.
- Hypospadias: never circumcise before repair; reconstruct at 6-18 months, treating chordee and the proximal meatus.
- Testicular torsion is a clinical diagnosis: immediate exploration and bilateral fixation; salvage falls sharply after 6 hours. Torsion of the appendix testis gives a blue dot sign and can be managed conservatively when the diagnosis is certain.
Worked example
A newborn boy has bilateral hydronephrosis, a thick-walled bladder and a poor stream. Catheterise to relieve obstruction, check creatinine and potassium, and perform a VCUG, which shows a dilated posterior urethra with a valve-like obstruction and bilateral reflux. The diagnosis is posterior urethral valves; treat hyperkalaemia, start antibiotics, and proceed to cystoscopic valve ablation, with lifelong follow-up of renal function and bladder dynamics.
Traps that cost marks
Missing posterior urethral valves in a boy with bilateral dilatation; delaying exploration for torsion; circumcising a hypospadiac penis; treating mild reflux aggressively while ignoring constipation; forgetting that antenatal pelvis diameter thresholds differ by gestational age.