Preterm delivery and ultrasound measurement of cervical length in Gran Canaria, Spain
Received 29 June 2009; received in revised form 31 July 2009; accepted 1 September 2009. published online 28 September 2009.
Abstract
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 37weeks, before 34weeks, and before 30weeks.
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% CI, 11.51–25.05); and 7.55 (95% CI, 5.44–10.5). Before the 34th week the ORs were 28.7 (95% CI, 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% CI, 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.
ABSTRACT