Sphincter rupture and anal incontinence after first vaginal delivery.

BACKGROUND

The aim of this prospective study was to establish the incidence of anal incontinence and sphincter defects after first vaginal delivery.

METHODS

A total of 99 nulliparous and pregnant women were examined prospectively 4 weeks (mean) before delivery and 4 months (mean) after delivery. Of the study population, 75 (76%) women had vaginal delivery and 24 (24%) had cesarean section. Vacuum extraction was necessary in 20 (20%) cases. The symptoms of anal incontinence were asked about using a standard questionnaire. Clinical examination, endoanal ultrasound (EAUS) and anal manometry were performed before and after delivery.

RESULTS

The symptoms of mild anal incontinence, mainly gas incontinence, increased after vaginal delivery more than after cesarean section (P < 0.032). Occult anal sphincter defects were noted in 17 (23%) of the 75 women after vaginal delivery by using EAUS. After vacuum extraction, anal sphincter defects were noted in nine (45%) out of 20 women. No new sphincter defects were found in the cesarean section group. The maximal squeezing pressures were significantly decreased in the patients with external anal sphincter (EAS) defects (P = 0.0025). Vacuum extraction leads to more sphincter defects but does not significantly increase anal incontinence or decrease mean anal sphincter pressures.

CONCLUSIONS

The first vaginal delivery can result in occult sphincter defects and the use of vacuum extraction increases the risk.