Measuring engagement of the fetal head: validity and reproducibility of a new ultrasound technique.
OBJECTIVE
Fetal head engagement can be assessed by translabial ultrasound and has been shown to be predictive of delivery 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 head engagement correlated strongly with abdominal palpation, full Bishop scores and vaginal assessment (all P < 0.001 for Kendall's tau-b). Intraclass correlation coefficients (n = 90) for the two methods were 0.75 and 0.92, signifying excellent interobserver agreement. Reproducibility was higher for the method using the central symphyseal axis as reference.


CONCLUSIONS
Quantitation of head engagement by translabial ultrasound is highly reproducible and correlates strongly with clinical measures of head engagement. We are now undertaking a prospective study to assess the predictive value of this new parameter for intrapartum events.
Dietz
H P
HP
Royal Prince Alfred Hospital, Sydney, Australia. hpdietz@bigpond.com
Lanzarone
V
V
D005260:Female; D006257:Head / Q000000981:diagnostic imaging / Q000196:embryology; D006801:Humans; D007746:Labor Presentation; D010173:Palpation / Q000379:methods*; D011247:Pregnancy; D011446:Prospective Studies; D015203:Reproducibility of Results; D016216:Ultrasonography, Prenatal / Q000379:methods*