Posterior urethral valves are the most common obstructive urethral lesion in newborn and infant males and the most common cause of end-stage renal disease in boys. They are partially obstructive and thus lead to variable degrees of back pressure damage to the urinary bladder and upper urinary tract. Dilation and obstruction of the prostatic urethra are always present. Spontaneous urinary ascites from the kidneys is often seen in neonates. This clear when the obstruction is relieved. About one-third of children with posterior urethral valves are now diagnosed by prenatal ultrasound. Another one-third are diagnosed in the first year of life, with the remaining third presenting later.Clinical manifestations consist of difficult voiding, a weak urinary stream, and a midline lower abdominal mass that represents a distended bladder.In some cases, the kidneys are palpable and the child may have signs and symptoms of uremia and acidosis. Urinary incontinence and urinary tract infection may occur. Laboratory findings include elevated serum urea nitrogen and creatinine and evidence of urinary infection. Ultrasound shows evidence of bladder thickening and trabeculation, hydroureter, and hydronephrosis. Demon­stration of urethral valves on a voiding cystourethrogram establishes the diagnosis, as does endoscopic identifica­tion of valves. Up to 70% of children with valves may have vesicoureteral reflux.TreatmentConsists of the destruction of the valves by endoscopic In a premature infant with a small urethra prohibiting transurethral resection, a temporary cutaneous vesicostomy may be required to provide drainage and improve impaired kidney function.