Posterior urethral valves: Case

This boy has posterior urethral valves presenting in the late, milder pattern. The two febrile urinary tract infections, the weak and dribbling stream, the daytime wetting, the growth faltering, the blood pressure at the 95th percentile, and the elevated creatinine for age are the clinical features, and the MCUG confirms the diagnosis with the dilated posterior urethra and the abrupt narrowing at the level of the valves. The bilateral grade 3 vesicoureteral reflux and the thick-walled bladder with a significant post-void residual are the expected associated findings. ^[1]

Clinical findings

The key clinical findings are the dilated posterior urethra with the abrupt narrowing on the MCUG, the bilateral moderate hydronephrosis, the thick-walled bladder with the post-void residual, the bilateral grade 3 reflux, the two febrile infections, the blood pressure at the 95th percentile, and the creatinine of 78 micromoles per litre in a 3-year-old. The growth on the 15th centile for weight and the blood pressure at the 95th percentile both signal the early chronic kidney disease and the hyperfiltration injury, which are the central concerns in a late-presenting boy. ^[2]

The differential for a boy with bilateral hydronephrosis and a thick-walled bladder includes posterior urethral valves, prune belly syndrome, a neurogenic bladder, and severe bilateral reflux. The MCUG showing the dilated posterior urethra with the abrupt narrowing is the discriminator that confirms the valves, because none of the mimics produce this sign. The normal abdominal wall excludes prune belly syndrome, and the absent spinal stigmata and the lower-limb neurology make a neurogenic bladder unlikely. ^[1]