Is cervical length evaluated by transvaginal ultrasonography helpful in detecting true preterm labor?

Research paper by Maria Carolina MC Maia, Roseli R Nomura, Fernanda F Mendonça, Livia L Rios, Antonio A Moron

Indexed on: 23 Jan '19Published on: 23 Jan '19Published in: The journal of maternal-fetal & neonatal medicine : the official journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatal Societies, the International Society of Perinatal Obstetricians


To investigate whether sonographic cervical markers can identify women in true preterm labor and predict delivery within 7 d and before 34 or 37 gestational weeks. This was a prospective observational study of women with singleton pregnancies and intact membranes given a diagnosis of preterm labor between 25 and 34 weeks and 6 d of gestation and who underwent transvaginal evaluation of the following characteristics: cervical length (CL), CL zeta score, absence of endocervical glandular echo, presence of cervical funneling, and presence of amniotic fluid sludge. The outcomes of interest were spontaneous delivery within 7 d of preterm labor and spontaneous delivery before 34 or 37 gestational weeks. The inclusion criteria were met by 126 women, 31 (25%) of whom were excluded and 95 were analyzed. The median gestational age at admission was 31.9 weeks. The median CL at preterm labor was 22.3 mm (range: 0-42.8 mm). The delivery occurred within 7 d of presentation in 13 (13.7%) cases. Delivery before 34 weeks occurred in 16 (16.8%) cases and before 37 weeks in 40 (42.1%) cases. Logistic regression analysis showed CL in millimeters was an independent predictor of delivery within 7 d (OR 0.918, 95% CI 0.862-0.978, p = .008). For birth before 34 weeks, the predictor was gestational age at admission (OR 0.683, 95% CI 0.539-0.866, p = .002) and before 37 weeks, the presence of cervical funneling (OR 3.778, 95% CI 1.460-9.773, p = .006). The CL ≤ 15 mm had sensitivity and specificity values of 77 and 77%, respectively, and good accuracy (88%) for prediction of delivery within 7 d. The evaluation of the cervix by transvaginal ultrasound in women in preterm labor predicted delivery within 7 d and helped distinguish between true and false labor. The analysis of CL zeta score was not an independent factor to predict delivery in 7 d.