Comparison of the Predictive Value of Transvaginal Cervical Length at 11-14 Weeks and at 20-22 Weeks of Gestation in Preterm Labour

Background: Preterm labour is defined as the onset of labour before 37 weeks of gestation, in pregnancy beyond 20 weeks of gestation, and is responsible for nearly 75% of all neonatal mortality and neurological morbidity. Cervical length (CL) is one of the major determinants of preterm delivery. Several studies have been able to conclude that transvaginal CL assessment may be a useful tool for the prediction of preterm delivery. The risk of preterm birth varies inversely with CL measured by ultrasound in low-risk women. Objective: To evaluate and compare the predictive value of transvaginal cervical length between 11-14 weeks and 20-22 weeks of gestation in preterm labour. Material and Methods: A total of 264 pregnant women who were primigravida, singleton pregnancy, and women at gestational age 11-14 weeks and 20-22 weeks were included in the study. They were subjected for CL measurement at 11-14 and 20-22 weeks of gestation using transvaginal ultrasonography with the standard longitudinal view of the cervix while the patient’s bladder was empty. GEL VOLUSON 730 PRO Trans Vaginal Ultrasound (TVS) probe IC 5-9 H instrument with 5-9 MHz was used to measure CL. Results: The variables analyzed were the mean cervical length at 11-14 weeks and 20-22 weeks, the rate of shortening of cervical length in those who deliver at term and preterm and the cervical length at 11-14 weeks 20-22 weeks was correlated with gestational age at delivery and the predictive value of the same was determined. Cut-off of cervical length at 11-14 and 20-22 weeks of gestation was 3.73 cm and 2.89 and was statistically significant for the prediction of pre-term labour. Reduction in cervical length from 11-14 weeks to 20-22 weeks of gestation of more than 0.7 cm is predictive of preterm labour with statistical significance (p<0.001). Conclusion: Routine mid-pregnancy cervical length assessment in low-risk women can be a cost-effective method of preterm birth reduction but the implementation of such a policy is highly dependent upon local factors. If it is to be undertaken, cervical length assessment should be performed according to a standardized technique.