Accuracy of Ultrasound Measurement of Fetal Head Station for Prediction of the Difficulty of Assisted Vaginal Delivery

Abstract

Background: Recently the use of ultrasound for the measurement of fetal head engagement during assisted vaginal delivery has increased. However, this finding has not been proved reproducible by sufficient studies and only limited-series studies have tested its accuracy.

Objective: To evaluate the accuracy of ultrasound measurement of perineum-to-skull ultrasound (PSUD) in predicting the outcome of assisted vaginal delivery.

Methods: A prospective cohort study was conducted in the Department of Gynecology and Obstetrics, Ibn-e-Siena Hospital, Multan, from September 2023 to September 2024. A total of 200 pregnant women with a gestation age of more than 34 weeks presenting with singleton pregnancies in cephalic position undergoing assisted vaginal delivery were included by consecutive sampling. Women were divided into group A, including women in whom PSUD was measured, and group B, which included women in whom PSUD was not measured. The difficulty of vaginal birth was primarily assessed by the extraction difficulty criterion. A digital vaginal examination was performed to record the fetal head station and presentation before each attempt of delivery according to ACOG classification and sections of the pelvic outlet. A suprapubic ultrasound was performed after examination.

Results The mean PSUD was 41.7±12.2 mm, and a higher PSUD was significantly related to extraction difficulty (p <0.0001). PSUD was not significantly associated with neonatal outcomes. The sensitivity for the prediction of difficult extraction was 73.5% at 40 mm PSUD, and the specificity was 48.2% (positive predictive value: 24.1% and negative predictive value: 89.4%). ....................