Pudendal nerve damage increases the risk of fecal incontinence in women with anal sphincter rupture after childbirth.

AIM: To evaluate anal function after childbirth in 94 women in whom sphincter rupture occurred and in 19 control women. The findings of anorectal physiological assessment and history of childbirth were related to the presence of fecal incontinence.
METHODS: Anal manometry and electromyography were performed the first days after childbirth and repeated 3 months post partum together with measurement of pudendal nerve terminal motor latency.
RESULTS: Eighteen patients (19%) presented with incontinence. None of the controls developed fecal incontinence after delivery. Anal manometry showed that both incontinent and continent patients had decreased resting and squeeze pressures compared to control subjects (p < 0.005). No difference in anal electromyography was found between the three groups. Both anal manometry and electromyography showed a significant increase in pressure and activity respectively 3 months after delivery in patients and controls. Patients with pudendal nerve terminal motor latencies > 2.0 milliseconds had an increased risk of having fecal incontinence compared to patients with pudendal nerve terminal motor latencies < or = 2.0 milliseconds (odds ratio 2.18, p < 0.05). Fecal incontinence could not be related to the weight or head circumference of the infant. The manometric and electromyographic findings, the use of pudendal nerve block, the length of the second stage of labor, the depth of rupture or the use of vacuum extraction could not be related to either fecal incontinence or pudendal nerve function.
CONCLUSION: The manometric findings indicated damage to the anal sphincter apparatus in both continent and incontinent patients. Decreased pudendal nerve function characterized incontinent women. Accurate prediction of fecal incontinence in women with obstetric anal sphincter rupture is not possible.