Three systematic reviews were identified. Only one (Jiang) included RCTs:
- A Cochrane review of selective versus routine use of episiotomy for vaginal birth (Jiang) says: “For women where an unassisted vaginal birth was anticipated, a policy of selective episiotomy may result in 30% fewer women experiencing severe perineal/vaginal trauma (RR 0.70, 95% CI 0.52 to 0.94; 5375 women; eight RCTs; low-certainty evidence).”
(Evidence level 1a)
- A review of episiotomy in vacuum-assisted delivery (Lund) included 15 observational studies and found that mediolateral or lateral episiotomy significantly reduced the risk of OASIS in vacuum-assisted deliveries in primiparous women (OR 0.53 (95% CI 0.37-0.77)).
- A review of morbidity associated with episiotomy in vacuum delivery (Sagi-Dain) noted “the suboptimal quality of the available evidence, which precludes us from drawing any solid deductions or recommendations”. The authors say “The results of our meta-analysis suggest that midline and mediolateral episiotomy in parous women may increase the rate of advanced perineal tears at vacuum delivery, and that lateral episiotomy in nulliparous women could be associated with a decreased risk of OASIS. In addition, mediolateral episiotomy could increase the risk of postpartum haemorrhage and pain.”
A review of 16 studies of obstetric anal sphincter injuries after episiotomy (Verghese) noted 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, mediolateral episiotomy reduced the risk of OASI (RR 0.67 95 % CI 0.49-0.92) in vaginal delivery.
(Evidence level III)
- Jiang H, Qian X, Carroli G, Garner P. Selective versus routine use of episiotomy for vaginal birth. Cochrane Database of Systematic Reviews 2017, Issue 2. Art. No.: CD000081. DOI: 10.1002/14651858.CD000081.pub3.
- Lund NS, Persson LK, Jangö H, Gommesen D, Westergaard HB. Episiotomy in vacuum-assisted delivery affects the risk of obstetric anal sphincter injury: a systematic review and meta-analysis. Eur J Obstet Gynecol Reprod Biol. 2016 Dec;207:193-199. Abstract. Full text available to RCOG Fellows, Members and Trainees.
- Sagi-Dain L, Sagi S. Morbidity associated with episiotomy in vacuum delivery: a systematic review and meta-analysis. BJOG. 2015 Jul;122(8):1073-81.
- Verghese TS, Champaneria R, Kapoor DS, Latthe PM. Obstetric anal sphincter injuries after episiotomy: systematic review and meta-analysis. Int Urogynecol J. 2016 Oct;27(10):1459-67
Classification of evidence levels
- Ia Evidence obtained from meta-analysis of randomised controlled trials.
- Ib Evidence obtained from at least one randomised controlled trial.
- IIa Evidence obtained from at least one well-designed controlled study without randomisation.
- IIb Evidence obtained from at least one other type of well-designed quasi-experimental study.
- III Evidence obtained from well-designed non-experimental descriptive studies, such as comparative studies, correlation studies and case studies.
- IV Evidence obtained from expert committee reports or opinions and/or clinical experience of respected authorities
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