Short-Term and Long-Term Outcomes and Predictors of Complications Following Major Obstetric Anal Sphincter Injuries

Obstetric anal sphincter injuries (OASIs) are among the most severe complications of vaginal delivery. Major OASIs (3c and 4th degree), often result in long-term morbidity affecting urinary, bowel, sexual and vaginal function domains. The aim of this study was to establish the difference in long-term outcomes between 3c and 4th degree OASIs on the different domains of pelvic floor function. We also established the association of known risk factors with adverse outcomes.

This project was a service evaluation at a UK tertiary hospital, analysing demographic, clinical and follow-up data for women with major OASIs. Outcomes and predictors of adverse outcome were assessed by retrospective record review and structured patient interviews using validated questionnaires.

A total of 207 women who suffered either a 3c or 4th-degree tears were compared. Of these 106 had a 3c and 101 had a 4th-degree tear. Women who suffered a 4th-degree tear showed higher rates of short-term bowel, long-term urinary and immediate/long-term vaginal complications. Long-term bowel outcomes were, however, similar in the two groups. Increased baby birthweight was found to have a significant association with long-term bowel and urinary complications after a 3c tear. This association was not seen for 4th-degree tears.

This study demonstrates that 4th-degree OASIs result in more severe and sustained functional impairment, especially for bowel, urinary and vaginal symptoms, than 3c tears. It also highlights the negative impact of increased baby birthweight on long-term bowel and urinary function in women suffering from a 3c tear during delivery. The findings highlight the need for robust, long-term follow-up and individualised management for women sustaining major perineal trauma.