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

Abstract

IntroductionThere is conflicting evidence on whether mediolateral episiotomy (MLE) reduces the risk of obstetric anal sphincter injuries (OASI) in spontaneous vaginal deliveries (SVD).ObjectivesA systematic review was undertaken to compare rates of OASI amongst women who had undergone mediolateral episiotomy versus those who did not.MethodsᅟSearch strategyElectronic 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 resultsOf 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.ConclusionThe 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.

Long‐term outcomes of the Stop Traumatic OASI Morbidity Project (STOMP)

“…Notably, the reduction in OASI rate observed in the study cohort was not associated with a change in episiotomy rates, as described for other interventions . Previous studies have indicated that episiotomy may be protective against OASI, and that the angle of the episiotomy cut affects outcomes . The OASI care bundle, which has been launched by the UK Royal College of Obstetricians and Gynaecologists, includes optimization of the angle of episiotomy as one of its components.…”

FIGO Statement: Restrictive use rather than routine use of episiotomy

“…A recent meta-analysis of observational data concluded that mediolateral episiotomy may reduce OASIS and should not be withheld, especially in nulliparous women. 12 In fact, after adjusting for confounding factors, mediolateral episiotomy has shown a significant 2.5 times reduction in developing lacerations in primiparous women compared with no episiotomy. 8 However, other studies have shown that episiotomy and 3rd or 4th degree perineal lacerations increase the risk of anal incontinence after vaginal birth by 1.7 and 2.7 times, respectively.…”

“…The effect of mediolateral episiotomy on obstetric anal sphincter injuries (OASIS) in spontaneous vaginal deliveries is not completely clear. A recent meta‐analysis of observational data concluded that mediolateral episiotomy may reduce OASIS and should not be withheld, especially in nulliparous women . In fact, after adjusting for confounding factors, mediolateral episiotomy has shown a significant 2.5 times reduction in developing lacerations in primiparous women compared with no episiotomy .…”

“…Mediolateral episiotomy is associated with a lower risk of obstetrical injuries, when compared with midline episiotomy . There are some modifications of the procedure that can reduce risk of lacerations.…”

“…6 Mediolateral episiotomy is associated with a lower risk of obstetrical injuries, when compared with midline episiotomy. 6,12 There are some modifications of the procedure that can reduce risk of lacerations. Performing an episiotomy before crowning is associated with increased vaginal trauma, longer average incision length, and greater average estimated blood loss, and should therefore in principle be avoided.…”