Early secondary repair of obstetric anal sphincter injuries (OASIs): experience and a review of the literature

Introduction and hypothesis Secondary anal sphincter repair for a dehisced obstetric anal sphincter injury (OASI) is required following 2.6% of primary repairs. There is growing evidence that instead of delaying repair for 3-6 months, early secondary repair of the anal sphincter can be completed within 14 days. Our aims were to review the literature and to describe experiences in our unit. Methods This is a narrative review of all published cases reporting outcomes of early secondary repair of dehisced OASIs. In addition, we report a series from Croydon University Hospital (CUH) between 2010 and 2019. Results Ninety patients from five studies were identified on literature search. Six patients from CUH were included in the case series. Overall, the most common complications following secondary repair included skin dehiscence [10.3% (n = 10)], infection [5.2% (n = 5)] and fistula formation [8.2% (n = 8)]. In our case series, following secondary repair, normal manometric incremental squeeze pressure was found in five women (83%). Also, on endoanal ultrasound, internal anal sphincter (IAS) defects were found in 75% with a history of IAS injury (n = 4). There were no full-thickness external anal sphincter defects. Compared to those requiring primary repair alone, residual defects were significantly larger in those who also underwent secondary repair (Starck score 2.1 vs. 5.7, p = 0.01). Conclusion Early secondary repair is a feasible surgical procedure for the reconstruction of dehisced OASIs. This case series and review of the literature can be used to support clinicians in the management of primary OASI repair dehiscence.