The effect of vaginal delivery on the pelvic floor.

This study was undertaken to determine the effects of vaginal deliveries on anorectal function, and to analyze the possible clinical, physiological, and radiological risk factors predisposing to damage of the pelvic floor musculature. We studied 25 consecutive women with a mean age of 32 years old, 3 months after vaginal delivery, 17 of whom were primiparae and 8, multiparae. The symptoms of anal incontinence were assessed, and anorectal manometry, rectal sensation, and radiological measurements of the anorectal angle and pelvic floor position at rest, on squeezing, and on straining were performed. As a control, six nulliparous women underwent the same examinations. Pelvic floor descent in both the primiparae and multiparae was significantly greater at rest and on squeezing than that in the nulliparous women. Furthermore, pelvic floor descent on straining was greater in the multiparae than in the nulliparous women (P = 0.028). An analysis of the 17 primiparae showed that prolonged duration of the second stage of labor and third-degree perineal tears were important factors predisposing to pelvic floor descent. In fact, 3 of the 17 primiparae (17%) had anal incontinence. These findings indicate that vaginal delivery may cause pelvic floor descent, an obtuse anorectal angle, and bowel symptoms.