The effect of a normal vaginal delivery on anal function

Background. To determine the effect of an uncomplicated vaginal delivery on anal sphincter function in primiparous women. Methods. In a prospective study, anal manometry was performed prenatally and at 4-6 weeks postnatally in 18 primiparous women (11 undergoing vaginal delivery; seven having Cesarean section). No patient had any evidence of anal sphincter damage after delivery as determined by anal ultrasound and pudendal nerve terminal motor latency. Results. Vaginal delivery was associated with a significant reduction in the squeeze pressure (SP: prenatal 269 cm H₂O vs postnatal 204 cm H₂O; p = 0.004) but not the resting pressure (RP: prenatal 96 cm H₂O vs postnatal 86 cm H₂O; p = 0.075). Cesarean section was not associated with any significant change in anal pressures. Conclusion. A normal vaginal delivery with no evidence of sphincter injury was associated with a significant effect on anal function when measured 4-6 weeks postnatally.