Correlation of the endoscopic and radiological anatomy of congenital obstruction of the posterior urethra and the external sphincter

Objective To determine whether the external sphincter is distal to congenital occlusion of the posterior urethra in boys by correlating endoscopic video-recorded information with cysto-urethrographic observations and assessing the anatomy of the disease. Patients and methods This study reviewed the endoscopic and radiographic findings in 42 boys (mean age 42 months, range newborn to 14 years), using material from a videotape library, and correlated these with the pre-operative cystogram. The nature of the obstructive lesion and its relationship to the verumontanum and the external sphincter was assessed. Results Of the 42 boys, 36 had the proximal extent of the external sphincter identified on the endoscopic video recording to be above the posterior urethral membrane; 22 of the membranes were obstructive. The proximal extent of the external sphincter was identified on the static cystogram images of only 31 of the 38 boys examined, but only ever above the posterior urethral membrane. Conclusion The proximal extent of the external sphincter, i.e. that portion which is most prominent endoscopically, is proximal to the membrane in congenital obstruction of the posterior urethra.