Antenatally detected kidney and urinary-tract anomalies: newborn management — formative SAQs

SAQ 1 — Bilateral hydronephrosis in a male newborn (10 marks)

A male infant is born at 39 weeks after a pregnancy complicated by bilateral renal pelvic dilatation (right APD 18 mm, left APD 14 mm), a thick-walled distended bladder, and oligohydramnios in the third trimester. He is well at birth with Apgar scores of 9 and 9. On examination the bladder is palpable and the urinary stream is weak. ^{[3] [7]}

a) What is the leading diagnosis, and which antenatal features support it? (3 marks) The leading diagnosis is posterior urethral valves (PUV). The supporting features are: male sex (PUV occurs only in males); bilateral hydronephrosis with APD values well above the high-risk threshold; a thick-walled distended bladder indicating bladder-outlet obstruction; and oligohydramnios, which signals reduced fetal urine output and bilateral renal impact. ^{[7] [3]}

b) Outline your immediate newborn management, including the timing and role of imaging and any medication. (4 marks) Immediate management is the high-risk protective bundle. Perform a renal ultrasound within 48 to 72 hours (or sooner given the bladder) to confirm the bilateral dilatation and bladder appearance. Insert a urethral catheter to decompress the bladder if the infant is in retention. Start a prophylactic antibiotic (confirm the exact agent and dose locally) pending exclusion of obstruction and reflux. Send baseline creatinine and electrolytes. Arrange urgent paediatric urology review for a voiding cystourethrogram (VCUG) to confirm the dilated posterior urethra and obstructing valve, followed by cystoscopic valve ablation. Maintain hydration and perfusion. ^{[3] [6]}

c) Describe the long-term follow-up this child will need and why. (3 marks) Even after successful valve ablation these boys face a high lifetime risk of chronic kidney disease — a recent systematic review and meta-analysis confirms a substantial proportion progress to end-stage renal disease. Long-term follow-up includes blood-pressure monitoring, growth surveillance, serial serum creatinine (tracked as eGFR), urinalysis for proteinuria, serial renal ultrasound, and bladder-function assessment (urodynamics). The child enters combined nephrology and urology follow-up with a plan for transition to adult renal care. ^[7]