Cervical HI-RTE elastography and pregnancy outcome: a prospective study

Abstract

Objective: To study cervix elastography measurement and its relation with pregnancy outcome.

Design: A two year prospective longitudinal study evaluated cervical elasticity by HI-RTE (Hitachi real-time tissue elastography) imaging during three trimesters of pregnancy. The main outcome measure was elastography index the cervical elastogram color-coded.

Results: Three hundred eighty seven measurements were realized among 72 pregnant women prospectively enrolled. In the first trimester, the elasticity index was significantly lower in women who subsequently had unfavorable outcome than in women who delivered at term (respectively, EI=0.51 (±0.04) and 0.59 (±0.02); P=0.037). The negative predictive value of posterior lip color (blue, blue-green=hard cervix) was high NPV=83.8 95% CI [68.8-92.4] in the first trimester (SE=64.7 95% CI [41.3-82.7]; SP=60.8 95% CI [47.1-72.9]; VPP=35.5 95% CI [21.1-53.1]). A first-trimester elasticity index threshold value ≤0.38 had a specificity of 98.0% and a NPV of 80.9% (Se 29.4%, PPV 83.3%). This index value, when combined with a cervical length less than or equal to 36mm, increased the risk of adverse outcome (HR 8.87 95% CI [3.22-23.7]).

Conclusions: Cervical elastography index is associated with unfavorable obstetrical outcomes, independently of cervical length. The study was registered in ClinicalTrials.gov under Identifier number NCT01032564.

Keywords: Cervical length; Elastography; Preterm birth; Transvaginal ultrasound.