How do vaginal delivery and elective cesarean section compare in short-term anal sphincter function?

Details

Fear that vaginal delivery may damage the pelvic floor and cause long-term urinary or anal incontinence is sometimes cited as a reason for cesarean section on request. This study aimed to compare anal sphincter function after vaginal delivery versus elective cesarean section.

In this longitudinal comparative study, researchers assessed 71 consecutive women six weeks before delivery and 52 of them 4–6 weeks after delivery. All women with occult sphincter lesions—lesions not recognized clinically—were assessed 3 months after delivery. Assessment included a bowel function questionnaire, anal endosonography, manometry, and measurement of pudendal-nerve terminal motor latency (PNTML).

Of the women assessed after delivery, 42 (80.8 percent) delivered vaginally and ten (19.2 percent) had an elective cesarean section at term. Clinically recognized anal sphincter injuries occurred in four women (9.5 percent); two of them developed incontinence for gas. The overall incidence of anal incontinence after vaginal delivery was 4.8 percent.

Endosonography identified occult sphincter defects in eight women (19 percent). At 3 months after delivery, no cases of any anal incontinence were reported. No woman delivered by cesarean section had altered anal continence or any significant change in anal pressures, rectal sensibility, or PNTML.

The authors concluded that severe sphincter tear is the single most important factor leading to anal incontinence in women. They stated that occult sphincter defects are rarely associated with short-term consequences but may predispose women to anal incontinence later in life. They recommended elective cesarean section for women at increased risk of anal incontinence.