Abnormal Cervical Remodeling Early Depiction by Ultrasound Elastography: Potential Opportunities for Preterm Birth Prevention and Delay

Abstract

Early depiction of abnormal cervical remodeling (CR) is a prime information source with days/even weeks to uterine contractions for preterm birth (PTB) risks. CR phases, softening-ripening-dilation, are distinctive by molecular, and timing in preterm/term: integrity loss in ripening and dilation. Changes in extracellular matrix, cellular content, water retention drive progressively to resistance reduction, rising elasticity, relaxing cervical smooth muscle cells (CSMCs) are organized like a sphincter at internal os. Shear Wave Elasticity Imaging-SWEI (dynamic elastography) based on objectively measurable cervical response to deformability is more accurate for early CR depiction from 8–12 weeks vs. conventional ultrasound cervical length (CL) measurements (16–23+6days weeks). SWEI quantifies tissue microstructure, constant fractional stiffness reduction (~ 4%/week), and spatial gradient in Shear Wave Speed (SWS) along cervix, and CL serial measurements in addition offers better strategies for prolongation, actual/future fetal safety, when cervical softness/shortness progresses. Vaginal progesterone (P4) from early pregnancy to complete 37 weeks is preventive: controls CR, indicated by SWS prior to CL < 25 mm, and cerclage (1–2 stiches) and/or pessary needs, adjuvant to cerclage, for CL < 15 mm after cerclage. Meta-analyses, systematic reviews proved P4 efficacy in prolongation (>28, 34, 37 weeks) in asymptomatic cases, with characteristic history/actual abnormal CR/shortness, a small better efficacy for vaginal P4, and cerclage vs. pessary, when separately analyzed; few retrospective studies exist on triple association efficacy for PTB prevention/delay and neonatal outcomes.