Ultrasonographic tools of preterm birth screening

Abstract

Preterm birth, delivery before 37 weeks of gestation, it's a global public health concern, leading to significant mortality and long-term health issues. Objective: To assess the effectiveness of the uterocervical angle compared to cervical length, measured through transvaginal ultrasonography in the second trimester of pregnancy, for predicting spontaneous preterm birth. Methods: This observational retrospective cohort study included all women with singleton pregnancies who presented for the second-trimester ultrasound in the Obstetrics and Gynecology Department of Centro Hospitalar Universitário São João, in Portugal, from January 2013 to October 2017. Uterocervical angle and cervical length were measured respecting Fetal Medicine Foundation guidelines. Results: Among 1,943 women, spontaneous preterm birth prevalence was 5.0%. Uterocervical angle ≥ 105o showed specificity of 87.4%, negative predictive value of 95.7%, sensitivity of 26.5%, and positive predictive value of 10.1%. Cervical length ≤ 25mm demonstrated specificity of 95.5%, negative predictive value of 95.2%, sensitivity of 11.2%, and positive predictive value of 11.8%. Regression models indicated an odds ratio for uterocervical angle of 1.01 (95% CI: 1.00 - 1.02, p = 0.034) and for cervical length of 0.92 (95% CI: 0.88 - 0.97, p < 0.001). Conclusions: Uterocervical angle performed less effectively than cervical length in predicting spontaneous preterm birth. While both markers had high negative predictive value, indicating a low likelihood of spontaneous preterm birth with a negative screen, sensitivity was low.