Delivery and pudendal nerve function

To assess the impact of mode of delivery and the occurrence of pelvic instability upon the pudendal nerve function and relate the pudendal nerve function to the occurrence of anal and urinary incontinence.

One hundred and forty-six pregnant women were examined during pregnancy and 12 weeks post partum with measurement of pudendal nerve terminal motor latency (PNTML), the difference between the two measurements was defined as delta PNTML. Anal and urinary continence status, details of delivery and the occurrence of pelvic instability were recorded prospectively.

Pudendal nerve terminal motor latency increased from 1.7 msec in primiparae and 1.8 msec in multiparae during pregnancy to 2.0 msec (p < 0.001) and 2.1 (p < 0.001) respectively after delivery. The increase was significantly higher after the use of vacuum extraction (p < 0.04). Multivariate analysis showed that delta PNTML was associated with age, the presence of pelvic instability and the use of vacuum extraction. Whereas delta PNTML was not associated with factors such as infant's head circumference and weight, parity, cesarean section, pudendal block, epidural analgesia and second stage of labor. Only four women had anal incontinence after delivery. Twenty-five women with urinary incontinence had a significantly higher mean PNTML (2.20 msec) than 121 continent women (2.01 msec).

Pudendal nerve terminal motor latency increases in both primiparous and multiparous women after delivery. In 10% of the women the increase resulted in a pathologic PNTML value > 2.4 msec. The delta PNTML was significantly associated with age, the occurrence of pelvic instability and the use of vacuum extraction. The group of women with urinary incontinence had a significant increased PNTML.