Publication:

To study the efficacy of digital and transvaginal ultrasonographic measurement of cervical length in asymptomatic high risk women at POG 16-24 weeks as a predictor of preterm delivery and progesterone and cerclage vs. progesterone alone for short cervical length in prevention of preterm labour

Background Objectives of current study were (i) To correlate the Cervical Length (CL) measured digitally and by transvaginal sonography (TVS) at 16 to 24 weeks with outcome of pregnancy (ii) Estimate risk of spontaneous preterm labour (PTL) based on CL measurements and (iii) study intervention in short CL and their effect on maternal and neonatal outcome.

Methods Women with singleton pregnancy at POG 16-24 weeks with history of previous preterm birth or mid trimester abortions were included in the study and subjected to digital assessment of CL followed by TVS measurement. In patients with TVS CL ≤25 mm, intervention in the form of progesterone or cerclage with progesterone was done. The outcome of the pregnancy in the form of delivery before completed 37 weeks or at and after 37 weeks was noted.

Results Twenty two subjects out of total 153 subjects (14.4%) had preterm delivery. The incidence of preterm delivery in study was 14.4%. Using Receiver Operating Characteristics (ROC) Curve, cut off value of digital CL was found to be 1.5 cm. The sensitivity, specificity, Positive Predictive Value (PPV), Negative Predictive Value (NPV) and accuracy of digital CL ≤1.5 cm in prediction of PTL were 72.7 %, 37.4%, 16.3%, 89.1% and 42.5% respectively. Cut off value of TVS CL by ROC curve was found to be 2.85 cm. The sensitivity, specificity, PPV, NPV and accuracy of CL (TVS) of ≤2.85 cm in prediction of PTL is 81.8%, 68.7%, 30.5%, 95.7%, 70.6% respectively. The outcome in form of PTL in 30 subjects, who had TVS CL ≤2.5 cm in both the intervention groups (McDonald stitch with progesterone and progesterone alone) was comparable (P value 0.60 not significant).

Conclusions The CL, both digitally and by TVS, was inversely correlated with the probability of preterm delivery so that the shorter the cervix, the greater the likelihood of preterm delivery. TVS CL is more predictive of preterm delivery than digital CL when performed between 16-24 weeks in asymptomatic high risk women. Intervention in short CL in form of McDonald’s stitch application with progesterone and progesterone alone have similar efficacy for prevention of PTL.