A critical evaluation of dissection of the perineum in synchronous combined abdominoperineal excision of the rectum.

Two methods of perineal dissection were studied in a prospective clinical trial of 62 consecutive patients undergoing synchronous combined abdominoperineal resection of the rectum for carcinoma. Of the 62 patients, 39 were included in method 1 and 23, in method 2. The technical difference and the merits between the two methods have been evaluated. The results showed that the operative injury to the anterior wall of the rectum occurred in three patients in the method 1 group and in eight patients in the method 2 group; but in the latter, the urethral injury occurred in one of 15 male patients. Apart from the operative injuries to the rectum or urethra, the factors influencing the bladder dysfunction after excision of the rectum have been reviewed. There was no evidence of bladder dysfunction in 62 patients. This was due to the fact that the plane of dissection in both methods was kept close to the rectum to avoid damage of the neural plexus supplying the external sphincter urethrae and the membranous urethra, which are vulnerable to injury in perineal dissection. It is questionable whether or not the bladder dysfunction is the consequence of the perineal dissection. Results of this study, therefore, suggest that the risk of injury to the rectum or urethra and the problems of bladder dysfunction are both avoidable if method 1 is used for abdominoperineal excision of the rectum.