Risk factors for obstetric anal sphincter injury recurrence: A systematic review and meta-analysis

Background: Women with previous obstetric anal sphincter injuries (OASIs) are at a higher risk of recurrence in the subsequent pregnancy, which may lead to the development or worsening of anal incontinence. Due to a lack of evidence, few recommendations can be made about the factors that may affect the risk of OASI recurrence. Objective: We sought to conduct a systematic review and meta-analysis to investigate potential risk factors for recurrent OASIs. Search strategy: Studies up to May 2019 were identified from PubMed, Scopus, Cochrane Library, and ISI Web of Science. Selection criteria: Studies assessing the impact of risk factors on OASI recurrence in subsequent pregnancies were included. Reviews, letters to the editor, conference abstracts, book chapters, guidelines, Cochrane reviews, and expert opinions were excluded. Data collection and analysis: Data were extracted by two independent reviewers. Odds ratio and standardized mean difference were chosen as effect measures. Pooled estimates were calculated using the random-effects model. Main results: The meta-analysis showed that maternal age, gestational age, occiput posterior presentation, oxytocin augmentation, operative delivery, and shoulder dystocia were associated with the risk of recurrent OASIs in the subsequent delivery. Conclusion: Prenatal and intrapartum risk factors are associated with recurrence of OASI. PROSPERO registration no. CRD42020178125.