Variable expression of the congenital obstructive posterior urethral membrane.

OBJECTIVES: To assess the variability of membranous folds in the posterior urethra and their relationship to urethral obstruction.

METHODS: Endoscopic video recordings of 19 boys with a membranous lesion in the posterior urethra were obtained over a 2.5-year period. Six had an endoscopy after a prenatal diagnosis of obstructive uropathy and 13 boys presented with either a urinary tract infection or hematuria.

RESULTS: Young's type I and type III appearances were seen in all with an obstructive membrane, and those with a less obstructing membrane probably had incidental pathologic conditions.

CONCLUSIONS: These observations support the thesis that the congenital attachment of the verumontanum to the anterior wall of the posterior urethra is the embryologic fore-runner to the congenital obstruction of the posterior urethra, and that there may be a variable degree of persistence of that attachment, which in some boys is not obstructive.