Obstetric anal sphincter injuries after episiotomy: systematic review and meta-analysis

Tina Sara Verghese, Rita Champaneria, Dharmesh S Kapoor, Pallavi Manish Latthe

Research output: Contribution to journalArticlepeer-review

40 Citations (Scopus)
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There is conflicting evidence on whether mediolateral episiotomy (MLE) reduces the risk of obstetric anal sphincter injuries (OASI) in spontaneous vaginal deliveries (SVD).


A systematic review was undertaken to compare rates of OASI amongst women who had undergone mediolateral episiotomy versus those who did not.

Search strategy

Electronic searches were performed in literature databases: CINAHL, Cochrane, EMBASE, Medline and MIDIRS from database inception to July 2015. Studies were eligible if MLE was compared to spontaneous tears and if OASI was the outcome of interest.

Two reviewers independently selected and extracted data on study characteristics, quality and results. We computed events of OASI in those who did and did not have an episiotomy from individual studies and pooled these results in a meta-analysis where possible.

Main results

Of the 2090 citations, 16 were included in the review. All were non-randomised, population based or retrospective cohort studies. There was great variation in quality amongst these studies. Data from 7 studies was used for meta-analysis. On collating data from these studies where the majority of women (636755/651114) were nulliparous, MLE reduced the risk of OASI (RR 0.67 95 % CI 0.49-0.92) in vaginal delivery.


The pooled analysis of a large number of women undergoing vaginal birth, most of who were nulliparous, indicates that MLE has a beneficial effect in prevention of OASI. An accurately given MLE might have a role in reducing OASI and should not be withheld, especially in nulliparous women. Caution is advised as the data is from non-randomised studies.
Original languageEnglish
Pages (from-to)1459-1467
JournalInternational Urogynecology Journal
Issue number10
Early online date19 Feb 2016
Publication statusPublished - Oct 2016


  • Obstetric anal sphincter injury
  • Mediolateral episiotomy
  • Spontaneous vaginal delivery
  • Perineum


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