The predictive value of ultrasonographic measurement of cervical length and width in preterm delivery

Objective:To evaluate the predictive value of cervical length and width in preterm delivery in asymptomatic nulliparous women.Methods:The authors performed transvaginal ultrasonographic examination at 24～35 weeks' gestation in 400 nulliparous women with singleton fetus to measure the length of uterine cervix and width of cervical internal os and follow up the pregnant outcome.Results:There were 28 spontaneous preterm births in 354 consecutive pregnant women. With the cervical length shortening, the risk of preterm delivery increased.When the cervical length≤30 mm, the sensitivity, the specificity, positive predictive value and negative predictive value was 17.9%, 97.5%,38.5% and 93.3%.The relative risk (RR) of preterm delivery was 5.7.When the width of cervical internal os≥5 mm, RR of preterm delivery was 3.95.Conclusion:The transvaginal ultrasonographic examination of uterine cervix is an objective, effective, and repeatable method in predicting preterm delivery.The cervical length less than 30 mm and the width of cervical internal os more than 5 mm, indicate a high risk of preterm delivery.