Preterm delivery and ultrasound measurement of cervical length in Gran Canaria, Spain

Objective: To study the relationship between cervical length measured by ultrasound and risk of preterm delivery. Methods: We measured cervical length in 2351 women between the 18th and 22nd week of pregnancy. Preterm, delivery was categorized as before 37 weeks, before 34 weeks, and before 30 weeks. Results: Before the 37th week, the odds ratios (ORs) of spontaneous delivery for cervical lengths in the 3rd, 5th, and 10th percentiles were, respectively, 25.47 (95% confidence intervals [CI], 15.5-41.73): 16.98 (95% Cl, 11.51-25.05); and 7.55 (95% Cl, 5.44-10.5). Before the 34th week the ORs were 28.7 (95% Cl, 14.54-41.73); 20.5 (95% CI, 11.51-25.05); and 10.3 (95% CI, 5.44-10.5). And before the 30th week they were 29.8 (95% Cl, 15.54-41.73); 23.1 (95% CI, 11.51-25.05); and 19.1 (95% CI, 7.44-31.5). In predicting premature delivery, the sensitivity, specificity, positive predictive value, and negative predictive value of cervical length were 26%, 98%, 63.6%, and 93.57% for the 3rd percentile; 34%, 97%, 51%, and 94% for the 5th percentile; and 39%, 92%, 31%, and 94% for the 10th percentile. Conclusion: Transvaginal measurement of cervical length during routine fetal morphological examination between the 18th and 22nd week of pregnancy helps identify asymptomatic women at risk for preterm delivery. (C) 2009 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.