Precision of Ultrasound During Peripartum for Predicting and Diagnosing Obstetric Anal Sphincter injuries

Abstract

Background: Early detection of obstetric anal sphincter injuries (OASIs) following vaginal delivery is essential for effective care and management.Obstetric anal sphincter injury (OASI) is the most common cause of anal incontinence in women and can have a devastating effect on a woman's mental and physical health as well as their social wellbeing. Other longterm effects after OASIS are perineal pain, dyspareuniaand more unusual abscess formation and anovaginal fistulas. This study aimed to assess the accuracy of transperineal ultrasound (TPUS) in diagnosing OASIs in primiparous women between 37 and 41 weeks of gestation. Methods: A cohort observational study was performed on 697 nulliparous women with singleton pregnancies at 37-41 weeks' gestation. The study involved prenatal ultrasound measurement of ano-vaginal distance (AVD) and postnatal evaluation of anal sphincter contraction. Results: Significant differences were observed between women with and without OASIs in terms of BMI, fetal parameters (BPD, HC, gestational age by US), and AVD. The area under the receiver operating characteristic curve (AUC) for AVD was 0.659 (95% CI: 0.583-0.735), indicating moderate predictive ability for OASIs. Multivariate analysis revealed significant correlations among BMI, AVD, duration of the second stage of labor, and fetal occiput position at delivery. The strongest correlation was between AVD and the duration of the second stage, while the weakest was between BMI and fetal occiput position. Conclusion: TPUS could serve as a valuable complement to clinical examination for identifying women at risk of OASIs, potentially lowering the incidence of undiagnosed or occult injuries. Enhanced training and competency assessment are crucial for improving OASIs detection by healthcare professionals.