Fully quantitative numeric cervical elastography outperforms cervical length for PTB prediction in asymptomatic patients

Abstract

To test a novel, fully quantitative cervical elastography system (FQ-CES) for preterm birth prediction and compare predictive characteristics to cervical length in asymptomatic patients. This is a prospective longitudinal cohort study of asymptomatic pregnant patients who underwent FQ-CES in the first, second, and third trimesters.We invented FQ-CES, which modifies a transvaginal ultrasound probe to quantify both pressure applied and tissue deformation, thereby yielding a fully quantified strain-based elastography system that provides a numeric quantification (Young’s modulus) of cervical tissue stiffness. This system is operator independent and can be compared across patients and within patients over time. Singleton pregnancies were included and imaging to obtain both FQ-CES and cervical length (CL) was performed at 11-23 weeks of pregnancy. Percentile rank of log-scaled Young’s modulus (logYM) was calculated, and patients were dichotomized into high and low cervical stiffness by the optimal significance of chi-square test. Prediction performance by FQ-CES and CL for preterm delivery < 37 weeks was assessed using ROC curves A total of 87 patients were included. The 15th percentile (logYM) was identified as the optimal cut-point to define low cervical stiffness. Patients with low cervical stiffness had a significantly higher risk for PTB than those with normal cervical stiffness (>15th percentile) (RR=2.9 95%CI [1.4, 6.1]). The FQ-CES was overall more predictive of PTB than cervical length (AUC 0.69 versus 0.53) (p=0.18) (Table and Figure). The predictive characteristics of FQ-CES logYM ≤ 15th percentile for PTB were: sensitivity 31%, specificity 91%, positive predictive value 50%, and negative predictive value 83%. FQ-CES performed at 11-23 weeks of pregnancy has better performance for preterm birth prediction than cervical length and could be used to refine risk stratification both clinically and for targeted enrollment in PTB intervention trials.View Large Image Figure ViewerDownload Hi-res image Download (PPT)