How time influences episiotomy utilization and obstetric anal sphincter injuries (OASIS)

Obstetric anal sphincter injuries (OASIS) pose significant challenges for young women following childbirth. The association between mediolateral episiotomy and OASIS remains a subject of debate and uncertainty. This study seeks to fill this gap.

This retrospective cohort study was performed using electronic database of obstetrics department at a tertiary medical center. All vaginal deliveries and vacuum-assisted deliveries at term, with a singleton live fetus at cephalic presentation between 2015 and 2021, were included. A comparison of the rates of mediolateral episiotomy and OASIS was conducted between the periods 2015-2017 and 2018-2021. Subgroup analysis was carried out based on parity and the mode of delivery.

Overall, the study included 18,202 women. Between 2015 and 2017, episiotomy was performed in 1,272 cases (17.5 %), compared to 1,241 cases (11.4 %) between 2018 and 2021 (p<0.0001). Conversely, a significant increase in OASIS was observed, rising from 0.3 % during 2015-2017 to 0.6 % during 2018-2021 (p=0.012). Multivariable analysis unveiled two factors significantly linked to OASIS: the temporal cohort studied, indicating an increasing trend in recent years, and the utilization of epidural analgesia, which exhibited a protective effect, while episiotomy was not associated with OASIS.

Our findings indicate a marked decline in the utilization of episiotomy over the study period, accompanied by an increase in OASIS incidence. Nevertheless, our analysis found no statistically significant link between episiotomy use and OASIS incidence.