The Effect of Vaginal Dissection on the Pudendal Nerve

OBJECTIVE:To determine the effect of vaginal dissection on the pudendal nerve. METHODS:Pudendal and perineal nerve terminal motor latencies 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 pelvic floor prolapse, and their mean preoperative pudendal and perineal nerve terminal motor latencies were prolonged compared to previously established normal values. The 27 women undergoing vaginal dissection demonstrated significant mean increases in pudendal nerve terminal motor 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. Clinically significant increases (more than 2 standard deviations) in pudendal or perineal nerve terminal motor latency occurred in 20 women (74%) in the vaginal dissection group and in seven women (33%) in the abdominally operated group. The odds ratio of producing such neuropathy by vaginal dissection compared to operating abdominally without vaginal dissection was 5.78 (95% CI 1.6-20). CONCLUSIONS:All women had abnormal preoperative pudendal nerve function, supporting previous reports linking pudendal neuropathy with pelvic floor prolapse. Pelvic floor surgery involving vaginal dissection produces neuropathy of the pudendal nerve as measured by terminal motor latency.