Effects of Pregnancy and Childbirth on the Pelvic Floor

Injury to the perineum, whether from episiotomy or spontaneous laceration, may result in loss of vaginal or rectal tone and/or anal incontinence. External anal sphincter defects can be identifi ed by endoanal ultrasound in 20% to 53% of women after normal vaginal delivery, a possible risk factor for anal incontinence that will be subsequently reported in 4% to 50% of cases. Flatal incontinence is reported six times more often by women who have experienced an anal sphincter injury during delivery. The risk of anal incontinence is increased with prolonged labor, forceps use, and episiotomy. The internal anal sphincter, extending an additional 12 mm cranial to the external sphincter margin, is prone to disruption by perineal lacerations and may be commonly overlooked during primary obstetrical repair. Using transanal ultrasonography, internal anal sphincter lacerations have been identifi ed in 17% of primiparas experiencing no visible perineal injury at delivery. Neurological injury to the anal sphincter may also play a role, explaining why normal function may not always be restored by surgical repair. Prolonged motor latencies may persist in the internal (upper) anal sphincter for up to fi ve months after vaginal delivery. Because of the limitations associated with the surgical repair of severe perineal and anorectal injuries, primary prevention of obstetrical trauma at the time of delivery should be considered the best approach for reducing chronic post-reproductive dysfunction in these areas. (Figure 3.2) Childbirth and the Pelvic Floor