Risk assessment for spontaneous preterm delivery according to cervical length in the first and second trimesters of pregnancy - Revista Brasileira de Ginecologia e Obstetrícia

Purpose: to evaluate, in the first and second trimesters of pregnancy, the correlation between cervical length and spontaneous preterm delivery. Methods: cervical length was evaluated in 641 pregnant women between 11-16 weeks’ and 23-24 weeks’ gestation. Cervical assessment was performed by a transvaginal scan with the patient with empty bladder in a gynecological position. Cervical length was measured from the internal to the external os. The gestational age at delivery was correlated with the length of the cervix. To compare the means in groups of pregnant women who had a term or preterm delivery, we used Student’s t test. Sensitivity, specificity, false-positive and false-negative rates, and accuracy were calculated for cervical length of 20 mm or less, 25 mm or less and 30 mm or less in the prediction of preterm delivery. Results: the measurement of cervical length, between 11 and 16 weeks of pregnancy, did not show any statistically significant difference on comparing women who had preterm and term delivery (40.6 mm and 42.7 mm, respectively, p=0.2459). However, the difference between the two groups at 23 to 24 weeks was significant (37.3 mm in the group who delivered prematurely and 26.7 mm in the term group, p=0.0001, Student’s t test). Conclusion: there was no significant difference in cervical length, at 11 to 16 weeks, between pregnant women who had a preterm and term delivery. However, at 23 to 24 weeks, cervical length was significantly different between the two groups, and this measurement might be used as a predictor for prematurity.