Rare combination of unilateral renal agenesis, congenital obstructive posterior urethral membrane, and enlarged prostatic utricle, with absence of hydroureteronephrosis.

The existence of congenital obstructive posterior urethral membrane (COPUM), extending proximally from the verumontanum toward the bladder neck, has been widely debated. Although COPUM often leads to chronic renal disease, a milder degree of obstruction and protective pressure pop-off mechanisms have been reported. We present a male infant with a rare combination of unilateral renal agenesis, COPUM proximally from the verumontanum to the bladder neck, and enlarged prostatic utricle. The posterior urethra was dilated, without bladder abnormalities or hydroureteronephrosis, indicating milder obstruction. Moreover, the enlarged prostatic utricle could contribute in the urinary tract protection, serving as an uncommon pressure pop-off mechanism.