Nomogram Use to Predict Obstetric Anal Sphincter Injuries prior to Term Vaginal Delivery [14R

Abstract

INTRODUCTION: Obstetric anal sphincter injuries (OASIs) following vaginal delivery are a significant complication. We previously identified and published significant independent risk factors for OASIs. A validated OASIs prediction model for women with known risk factors planning vaginal delivery is needed to facilitate patient counseling and shared treatment decision-making. METHODS: We performed a retrospective cohort study including women having had vaginal deliveries (2006-2015), with demographic and obstetric data abstracted through medical record review. Results were adjusted for potential confounding factors. Nomogram developed using logistic regression analyses that included risk factors taken from published OASIs literature. Dataset was divided into training and test datasets for internal validation. Prediction nomogram was constructed using regression-based coefficient scoring system with a correlated probability of OASIs. RESULTS: Among 16,024 included vaginal delivery, 1106 (6.9%) were complicated with an OASIs. Predictors identified in the train cohort were: Asian race, nulliparous status, increased age, birth-weight, birthweight-maternal body mass index ratio (BW:BMI), smoking status, gestational age, parity, episiotomy, trial of labor after cesarean, and operative vaginal deliveries. The constructed nomogram was internally validated. CONCLUSION: This study confirmed known OASIs risk factors among women having term vaginal deliveries. Furthermore, we established and validated a novel nomogram for the prediction of OASIs for the women giving vaginal deliveries with known risk factors for severe perineal laceration. If nomogram is externally validated, it would be an excellent counseling tool for women with increased probability of OASIs.