Cervical strain elastography: pattern analysis and cervical sliding sign in preterm and control pregnancies

Objectives The aim of this study was to assess the value of cervical strain elastography and Cervical Sliding Sign (CSS) for predicting spontaneous preterm birth (sPTB). Methods In our case-control study we performed an elastographic assessment of the cervix in 82 cases of preterm birth (preterm group) and 451 control pregnancies (control group) between the 20th and 37th week of gestation. We divided the anterior cervical lip first into two ("Intern2", "Extern2") and into three sectors ("Intern3", "Middle3", "Extern3"). The tissue deformation pattern after local compression with an ultrasound probe was recorded. We distinguished between an irregularly distributed ("Spotting") and homogeneous pattern presentation. Additionally, the presence of a sliding of the anterior against the posterior cervical lip (positive CSS) during compression was evaluated. A logistic regression analysis and the Akaike Information Criterion (AIC) were used to estimate the probability of sPTB and to select a prediction model. Results Spotting and positive CSS occurred more frequently in the preterm group compared to control group (97.8 vs. 2.2%, p<0.001; 26.8 vs. 4.2%, p<0.001; respectively). The model with the parameters week of gestation at ultrasound examination, Intern3, Middle3 and CSS was calculated as the highest quality model for predicting sPTB. The AUC (Area Under the Curve) was higher for this parameter combination compared to cervical length (CL) (0.926 vs. 0.729). Conclusions Cervical strain elastography pattern analysis may be useful for the prediction of sPTB, as the combination of Spotting analysis and CSS is superior to CL measurement alone.