Does transvaginal sonographic measurement of cervical length before 14 weeks predict preterm delivery in high‐risk pregnancies?

<jats:title>Abstract</jats:title><jats:sec><jats:title>Objective</jats:title><jats:p>To determine whether high‐risk patients manifest cervical length < 25 mm on transvaginal ultrasound before 14 weeks of gestation, and if this finding is predictive of preterm delivery.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>Asymptomatic pregnancies at high risk for preterm birth were followed prospectively from 10 + 0 weeks to 13 + 6 weeks with transvaginal sonographic measurement of the cervix. A cervical length < 25 mm was considered a short cervix at this gestational age and at the follow‐up ultrasound examinations, performed between 14 and 24 weeks. The primary outcome was preterm birth at < 35 weeks of gestation.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>One hundred and eighty‐three pregnancies met the study criteria and were included in the analysis. Only 10 (5%) patients had a cervix < 25 mm before 14 weeks. The sensitivity, specificity and positive and negative predictive values of a short cervix were 14%, 97%, 50%, and 82%, respectively (relative risk, 2.8; 95% confidence interval, 1.4–5.6). The mean transvaginal sonographic cervical length before 14 weeks of gestation was 33.7 ± 6.9 mm in pregnancies which delivered preterm (<jats:italic>n</jats:italic> = 36), and 35.0 ± 6.8 mm in those delivering at term (<jats:italic>n</jats:italic> = 147) (<jats:italic>P</jats:italic> = 0.3). Follow‐up transvaginal ultrasound examination of the cervix to 24 weeks revealed that the average gestational age at which a short cervix was detected was 18.7 ± 2.9 weeks.</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>A cervical length < 25 mm on transvaginal sonographic assessment rarely occurs before 14 weeks even in high‐risk patients destined to deliver preterm; in these patients cervical changes predictive of preterm birth develop mostly after this gestational age. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.</jats:p></jats:sec>