Measuring engagement of the fetal head: validity and reproducibility of a new ultrasound technique

Objective Fetal bead engagement can be assessed by translabial ultrasound and has been shown to be predictive of deliver), mode. We attempted to validate the technique by comparing ultrasound with abdominal and vaginal palpation. Reproducibility was tested in a blinded test- retest series. Methods In a prospective clinical study, 139 nulliparous women between 35 + 3 and 40 + 4 weeks' gestation were assessed by translabial ultrasound, abdominal palpation of the fetal head (n = 139) and vaginal examination (n = 112). Ultrasound was performed using two methods, with the symphysis pubis as reference. A test-retest series was performed in 90 women. Results Ultrasound of bead engagement correlated strongly with abdominal palpation, full Bishop scores and vaginal assessment (all P < 0.001 for Kendall's taub). Intraclass correlation coefficients (n = 90) for the two methods were 0.75 and 0.92, signifying excellent inter-observer agreement. Reproducibility was higher for the method using the central sympbyseal axis as reference. Conclusion Quantitation of bead engagement by translabial ultrasound is highly reproducible and correlates strongly with clinical measures of bead engagement. We are now undertaking a prospective study to assess the predictive value of this new parameter for intrapartum events. Copyright (C) 2004 ISUOG. Published by John Wile), Sons, Ltd.