Management of a Complex Obstetric Anal Sphincter Injury

Objectives: Obstetrical anal sphincter injuries (OASIS) are estimated to occur in 11% of vaginal deliveries. Adequate identification of OASIS is essential since these injuries can have a huge impact on a woman's quality of life and future fertility. Furthermore, OASIS can cause anal incontinence in reproductive age women; a condition with a severe social, psychological, sexual, and economic impact on women. Trainees report a decrease in competency in the identification and management of OASIS. Lack of formal training and familiarity with anatomy leads to improper identification and suboptimal repair. To develop tools to aid in the proper identification, repair technique, and postoperative management of OASIS, we developed a surgical video to describe technical considerations in managing a complex perineal laceration.

Methods: Our patient presented with a complete defect of the anal sphincter complex with a one-centimeter rectovaginal fistula following an operative vaginal delivery. MRI performed was consistent with these findings. A multidisciplinary team consisting of colorectal surgery and urogynecologist performed the rectovaginal fistula repair and sphincteroplasty. The procedure started with a curvilinear incision made from the 9 to 3 o'clock position. A tear-drop incision was made about the fistula and the surrounding vaginal epithelium was mobilized circumferentially to allow for a tension-free closure. The retracted anal sphincter muscles were identified using a muscle stimulator and dissected free using sharp and cautery dissection. Once adequate dissection was achieved to allow for a vest-over-pants closure, attention was turned to the fistula repair. An incision was made in the anus and extended cephalad toward the fistula. The fistula tract was excised, and the anal mucosa closed in 2 layers. The external anal sphincter was then brought together in a vest-over-pants fashion using delayed 2.0 PDS sutures. To avoid constriction at the introitus, a vaginal advancement flap was then undertaken. The patient was discharged on POD 1 on a 7-day course of Cefaclor and Flagyl. Analgesia was maintained with scheduled ibuprofen and acetaminophen for 2 weeks (with narcotics used only for breakthrough pain). She was instructed on PeriCare (clean her bottom with water or by sitz bath after BM) and to take fiber (e.g., Fybogel 1 sachet 2 times per day for two weeks) and Lactulose 15 ml twice daily to avoid constipation. At her 6-week visit, she was noted to have resolution of her fistula, anal continence, and adequate vaginal caliber. There was a superficial breakdown of the perineal body skin which healed spontaneously in 3 months.

Clinical Relevance: Complex obstetric anal sphincter injuries can benefit from a multidisciplinary team. In addition to adhering to meticulous hemostasis, tension-free closure, and adequate sphincter muscle mobilization, the team should provide clear patient instructions to avoid infection and constipation as these may undermine the best of surgical repairs.