Best Approach for a Young Woman with Anal Incontinence Following OASI Repair

Anal incontinence (AI) is the most degrading benign condition that any human being has to endure, and vaginal birth is the major cause. When AI develops after an OASI repair, a careful history should be taken regarding the consistency of stool and type of incontinence (flatus, passive leakage, urgency related incontinence). Most women would be given stool softeners/laxatives after the repair and therefore if the stool is very loose, AI is more likely to occur even with a good repair. In general, when symptoms appear in the early postpartum period, a secondary repair would not be performed unless it is suspected that the repair was inappropriate e.g., superficial transverse perineal muscle repaired instead of external sphincter (Sioutis et al 2017) or if there is breakdown of the OASI wound (Okeahialam et al 2021). Under these circumstances, endoanal ultrasound would be the preferred investigation (Okeahialam et al 2022) to delineate the ends of the torn muscles and also ensure that the full extent of the injury had not been underestimated. Moreover, one needs to be aware that AI may be due to a pelvic/pudendal neuropathy and therefore digital rectal assessment should be performed to assess the contractility of the residual anal sphincter and the levator ani muscles. Poor contractility of the levator ani would suggest global pelvic floor and anal sphincter neuropathy. This is likely to recover with physiotherapy and if necessary, electrical muscle stimulation.

When perineal wound infection occurs, even with perineal wound breakdown, the repaired OASI does not usually breakdown (Okeeahialam et al 2023). Complete dehiscence of a primary OASI repair requiring secondary anal sphincter repair occurs in 2.6% of women following primary repair. However, if it does breakdown, then repair should be performed within a few days following wound irrigation and antibiotics. There is no benefit in waiting for the traditional 3 to 6 months previously advocated by colorectal surgeons. Early secondary repair (defined as within 14 days of primary repair) minimizes the risk of fibrosis and atrophy of the anal sphincter muscles which can retract. Early repair also allows for repair of the internal sphincter if necessary. The swing to the early approach has also been seen in fistula surgery where women are spared the suffering, humiliation and poor quality of life while being ostracized by society. There is no evidence that a prolonged delay in fistula repair provides a better outcome. Given that the long-term result of late secondary sphincter is unfavorable (Glasgow et al 2012), women need to be counseled and offered the opportunity of early anal sphincter repair.

REFERENCES

Sioutis D, Thakar R, Sultan AH. Overdiagnosis and rising rate of obstetric anal sphincter injuries (OASIS): time for reappraisal. Ultrasound Obstet Gynecol. 2017;50(5):642-7.

Okeahialam NA, Thakar R, Sultan AH. Early secondary repair of obstetric anal sphincter injuries (OASIs): experience and a review of the literature. Int Urogynecol J. 2021;32(7):1611-22.

Okeahialam NA, Thakar R, Sultan AH. Comparison of diagnostic criteria for significant anal sphincter defects between endoanal and transperineal ultrasound. Ultrasound Obstet Gynecol. 2022;60(6):793-9.

Okeahialam NA, Thakar R, Sultan AH. Postpartum perineal wound infection and its effect on anal sphincter integrity. Results of a prospective observational study. Acta Obstet Gynecol Scand. 2023 Jan 27. doi: 10.1111/aogs.14515. Epub ahead of print. PMID: 36707852.

Glasgow SC, Lowry AC. Long-term outcomes of anal sphincter repair for fecal incontinence: a systematic review. Dis Colon Rectum. 2012;55(4):482-90.