Episiotomy practice in France and prevention of high-grade perineal tears at the time of operative vaginal delivery: a prospective multicentre ancillary cohort study

Introduction and hypothesis Evidence suggests that episiotomies reduce the risk for obstetric anal sphincter injuries (OASIs) in operative vaginal deliveries (OVDs). However, there is limited evidence on the importance of episiotomy technique in this context. The primary objective of this study was to assess if an episiotomy suture angle >45 degrees from the median line would be associated with a lower risk for OASIs at the time of OVD. Methods This was an ancillary study from the multicentre prospective cohort INSTRUMODA study. Of the 2,620 patients who had an OVD with a concomitant episiotomy between April 2021 and March 2022, a total of 219 fulfilled the inclusion criteria. Post-suturing photographs were used to assess episiotomy characteristics. Results Based on suture angles of <= 45 degrees and >45 degrees the study cohort was categorized into groups A (n = 155) and B (n = 64) respectively. The groups had comparable demographic and birth-related characteristics. The mean episiotomy length was significantly longer in group A than in group B (3.21 cm vs 2.84 cm; p = 0.009). Senior obstetricians performed more acute angled episiotomies than junior residents (p = 0.016). The total prevalence of OASIS was 2.3%, with no significant difference in rate of OASI between the two study groups. Birthweight was significantly higher in OASI births (p = 0.018) and spatula-assisted births were associated with higher risk for OASIs than ventouse or forceps (p = 0.0039). Conclusions This study did not demonstrate a significant reduction in risk for OASI at the time of OVD when the episiotomy suture angle was >45 degrees from the median line. However, these results should be interpreted with caution owing to the low prevalence of OASIs in our cohort.