THE EFFECT OF VAGINAL DISSECTION ON THE PUDENDAL NERVE

Objective: To determine the effect of vaginal dissection on the pudend al nerve. Methods: Pudendal and perineal nerve terminal motor latencie s were measured before and at least 6 weeks after either abdominal or vaginal surgery for genital tract prolapse with or without urinary and fecal incontinence. Forty-eight women were studied prospectively in a randomized, blinded fashion. Results: All women in this study had pel vic floor prolapse, and their mean preoperative pudendal and perineal nerve terminal motor latencies were prolonged compared to previously e stablished normal values. The 27 women undergoing vaginal dissection d emonstrated significant mean increases in pudendal nerve terminal moto r latency (0.63 milliseconds, 95% confidence interval [CI] 0.33-0.93; P = .001) and perineal nerve terminal motor latency (1.33 milliseconds , 95% CI 0.80-1.86; P = .0001). In the 21 who had abdominal operations without vaginal dissection, essentially no mean change was noted. Cli nically significant increases (more than 2 standard deviations) in pud endal or perineal nerve terminal motor latency occurred in 20 women (7 4%) in the vaginal dissection group and in seven women (33%) in the ab dominally operated group. The odds ratio of producing such neuropathy by vaginal dissection compared to operating abdominally without vagina l dissection was 5.78 (95% CI 1.6-20). Conclusions: All women had abno rmal preoperative pudendal nerve function, supporting previous reports linking pudendal neuropathy with pelvic floor prolapse. Pelvic floor surgery involving vaginal dissection produces neuropathy of the pudend al nerve as measured by terminal motor latency.