Obstetric anal sphincter injuries (OASIS) incidence. Twenty-five years’ evolution

Introduction

Pelvic floor disorder is an issue that affects quality of life. Obstetric anal sphincter injuries (OASIS) are related to vaginal parity and can lead to anal incontinence in 60% of women in the long term. Its identification is crucial to perform optimal surgical repair. The aim of the study was to describe obstetric trauma in our population and evolution in a 25-year period.

Material and methods

Observational retrospective study of woman who delivered in Hospital Parc Taulí between 1998 and 2021. Patients without vaginal delivery or delivery before 22nd gestational week were excluded. Data processing and analysis were performed using Excel.2016 and IBM SPSS Statistics 17.0.

Results

Sixty thousand one hundred forty-five women who delivered in our hospital over the study period were included. Fifty thousand twenty-two (83.17%) had a vaginal delivery: 82.12% were eutocic and 17.22% operative assisted. Loco regional anaesthesia was performed in 81% and the overall episiotomy rate was 59.7%. OASIS were reported in 369 women, constituting 0.74% of all vaginal deliveries, the major part detected in Kjelland forceps deliveries (representing 46.8% of OASIS) and eutocic deliveries (41.5%). Analysing the evolution of OASIS, an important reduction from 2018 to 2021 was noticeable (1.1 vs. 0.6%) and also a statistically significant difference in OASIS rate between operative and eutocic deliveries (p < 0.05).

Conclusions

The study agrees with the literature on the predominance of OASIS in forceps deliveries. It evidences a decrease in operative vaginal deliveries parallel to a significant decline of OASIS since 2018, when vacuum deliveries increased in detriment of forceps. Establishment of regular training programs appear to increase OASIS detection.