Elastography for predicting preterm delivery in patients with short cervical length at 18-22 weeks of gestation: a prospective observational study

Abstract

Objectives: The aim of the study was to estimate the potential value of elastographic evaluation of the internal cervical os at 18-22 weeks of pregnancy in patients with short cervical length for prediction of preterm delivery (PTD). Material and methods: This prospective observational study included 109 patients with cervical length of ≤25 mm at 18-22 weeks scan. Stiffness of the internal cervical os was assessed by elastography. Elastographic assessment of the internal os was performed using a color map: red (soft), yellow (medium soft), blue (medium hard), and purple (hard). If two colors were visible in the region of the internal os, the softer option was noted. The following outcome measures were analyzed: percentage of PTDs in various categories of elastographic cervical assessment, sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) of elastography in predicting PTDs. Additionally, ROC curves were constructed for elastography and cervical length for predicting PTDs. Results: Forty-five cases of PTDs (<37 weeks of pregnancy) were found in the studied population. The number of PTDs was significantly higher in the red group, than in the blue and purple groups. The sensitivity, specificity, NPV and PPV for the assessment of both, red and yellow internal os for predicting preterm delivery were 82.2%, 75.0%, 84.0% and 72.5% respectively. The cut-off value for elastography suggested inclusion of both, red and yellow (warm) colors as predictors of PTD. Conclusions: Elastographic evaluation of the internal cervical os at 18-22 weeks of pregnancy in patients with short cervical length may be useful in predicting PTD.