Comparison of OASI rates and risk factors in ventouse assisted and unassisted births
S Basude, R Bahl

Introduction

Primiparity is a known risk factor for Obstetric anal sphincter injury (OASI). Particularly higher rates of OASI have been noted in primiparous women in our unit. Our objective was to ascertain the rates of OASI with regards to different modes of vaginal births in St Michael’s hospital. To compare the OASI rates and risk factors in Primigravidae in the two modes of birth groups with the lowest OASI rates to inform areas for consideration to further reduce OASI rates.

Conclusions

Primary risk factors identified by Stendenfelt etal include primiparity, assisted vaginal birth and birth weight (BW) over 4000g. Furthermore, one of the OASI2 care bundle recommendations is to perform episiotomy when indicated. Of the types of vaginal births, UAB are known to have the lowest OASI rates. However in our cohort UAB rates were higher as compared to VAB irrespective of the risk factors, except in the groups who had episiotomy. This may suggest that there may be a need to lower the threshold of considering use of episiotomy in primigravida having UAB.