Association between severity of obstetric perineal tears and risk of levator ani avulsion - a systematic review

AIM: The aim of this study was to investigate whether the incidence of levator ani avulsion (LAA) is associated with the degree of obstetric tear.

METHODS: This systematic review was conducted in accordance with the PRISMA guidelines. A literature search was performed in PubMed, the Cochrane Library, and Embase. Articles were screened by two independent reviewers, and data were extracted on study characteristics, number of included women, degree of obstetric perineal tear, and the incidence of levator ani avulsion (LAA).

RESULTS: A total of 13 studies were included, comprising 3,584 primiparous women. We found that the incidence of levator ani avulsion was 13 % (95 %CI: 10-17 %) in women without a perineal tear, 24% (95 %CI: 20-29 %) with a first-degree tear, 22 % (95 %CI: 18-25 %) with a spontaneous second-degree tear, 23 % (95 %CI: 17-29 %) with an episiotomy, and 35% (95 %CI: 30-40 %) with an obstetric anal sphincter injury (OASI). Additionally, some studies grouped women with no, first-, or second-degree tears together and here the incidence of LAA was 16% (95 %CI: 14-18 %).

CONCLUSION: LAA is common after vaginal delivery and is related to the degree of obstetric tear, ranging from 13 % in women without perineal tear to 35 % with OASI.