Changes in shear wave speed pre- and post-induction of labor: A feasibility study

Abstract

Objective To explore the feasibility of using shear wave speed (SWS) estimates to detect differences in cervical softening pre- and post-ripening in women undergoing induction of labor. Methods Subjects at 37-41 weeks' gestation undergoing cervical ripening before induction of labor were recruited (n-=-20). Examinations, performed prior to administration of misoprostol and 4-h later included Bishop score, transvaginal ultrasound measurement of cervical length, and 10 replicate SWS measurements using an ultrasound system equipped with a prototype transducer (128 element, 3-mm diameter, 14-mm aperture) attached to the clinician's hand. Subjects were divided into two groups, 'not-in-labor' and 'marked-progression', based on cervical evaluation at the second examination. Measurements were compared via individual paired hypotheses tests and using a linear mixed model, with the latter also used to compare groups. Spearman's rank correlation coefficient was used to compare SWS with Bishop score. The linear mixed model can take into account clustered data and accommodate multiple predictors simultaneously. Results The Wilcoxon signed-rank paired test established a significant difference in pre- and post-ripening SWS, with mean SWS estimates of 2.53-±-0.75 and 1.54-±-0.31-m/s, respectively (P-