Urodynamic studies before and/or after abdominoperineal resection of the rectum for carcinoma.

Urodynamic studies were performed on 62 patients who underwent abdominoperineal resection of the rectum during the last 14 months. Of these patients 20 were evaluated preoperatively and postoperatively, and 42 were studied postoperatively only. Urodynamic studies consisted of cystometry, urethral sphincter electromyography and uroflowmetry. The results of these studies revealed a significant decrease in effective bladder capacity, and increases in first sensation to void and residual urine postoperatively. The peak and average urinary flow rates also were decreased significantly. No significant changes could be found in urethral sphincter electromyography. The incidence of complete denervation of the bladder in our study was 11.3 per cent. More severe voiding dysfunction was found in patients with stage C2 anorectal tumors than in those with stage B2 disease and in patients with tumors 4 to 8 cm. from the anal verge. Urodynamic evaluation, especially cystometry, is necessary after abdominoperineal resection to detect voiding dysfunction.