CONGENITAL URETHRAL OBSTRUCTION - COBBS COLLAR OR PROLAPSED CONGENITAL OBSTRUCTIVE POSTERIOR URETHRAL MEMBRANE (COPUM)

Objective To determine whether there are two distinct types of congeni tal obstruction of the proximal urethra. Patients and methods Three bo ys with a congenital bulbar urethral narrowing (Cobb's collar) were ex amined. Recent papers on congenital obstructive posterior urethral mem brane (COPUM) were reviewed. Results The more proximal lesion is a mem branous obstruction which is able to prolapse as far as the bulbar ure thra, but has paramedian folds that attach along the posterior wall of the urethra to the verumontanum, and is due to persistence of an embr yological attachment between the distal verumontanum and the anterior wall of the posterior urethra. The more distal narrowing is not always obstructive and is primarily a bulbar urethral membrane, is independe nt of the verumontanum and external sphincter, and may represent a per sistence of part of the urogenital membrane. Conclusions There are two distinct types of congenital obstruction of the proximal urethra, wit h the association to the verumontanum being the distinguishing feature .