[Neonatal urinary ascites secondary to posterior urethral valves]

Urine collection within the perirenal spaces and subsequent urinary ascites may be caused either by calyceal perforation or filtration through the walls of urinary tract as a consequence of urinary obstruction. The obstruction to urine deflow is more frequently secondary to the presence of posterior urethral valves (PUV) in the paediatric age group. Urine collecting within the perirenal spaces may act as a decompressive mechanism that allows endoluminal pressure to decrease, being thus glomerular function and prognosis improved. The case of a newborn in poor clinical conditions with PUV who underwent an emergency surgical procedure for the onset of urinary ascites is described. On operation, no perforation of the upper urinary tract was found, being urinary ascites probably caused by filtration secondary to increased endoluminal pressure. PUV were coagulated by means of a Bugbee electrode and a nephrostomy set in place. Congenital obstruction of the urinary tract caused by PUV may lead to renal, ureteric and vesical damages. Surgery is necessary in order to preserve and improve renal function.