PREDICTION OF PRETERM DELIVERY BY ASSESSMENT OF CERVICAL LENGTH USING TRANSVAGINAL ULTRASOUND

AIMS AND OBJECTIVES: To identify patients at risk of preterm deliveries before the onset of symptoms. Purpose of this study is to assess the diagnostic performance of transvaginal ultrasonographic evaluation of cervix in the prediction of preterm delivery. MATERIAL AND METHODS: Sonographic cervical length assessment in 200 antenatal women between 20 – 28 weeks gestation attending OPD was done. Study group was divided in group A (Those with cervical length more than 25mm) and group B (those with cervical length ≤25mm, again these women with short cervix divided in Group B1-Women with cervical length 21–25mm, Group B2-Women with cervical length ≤20mm). Cervical length was measured for all enrolled women using 6.5 MHz transvaginal probe. Cervical length on transvaginal sonography ≤25mm were considered as short cervix and remaining (>25 mm) were considered as normal cervical lengths. In present study, women with short cervix ≤25 mm and history of previous preterm delivery or second trimester abortions and evidence of cervical defect were treated with elective cervical cerclage by McDonald method. Women in group A and remaining women in group B (who had short cervix but os was closed and women without history of previous preterm delivery or second trimester abortions) were conservatively followed up. RESULTS: Out of 200 women 5(2.5%) women had cervical lengths ≤20 mm measured with TVS (Group B2); 11(5.5%) had cervical lengths ranging from 21-25mm (group B1). Out of 16 women (group B); 9(4.6%) women underwent elective cerclage and remaining 7(3.6%) women were managed conservatively. Incidence of preterm delivery in group A was 5.6% while in group B it was 75%. Relative risk of preterm delivery in group B was 13.35 (P=0.0000000 ←). Odds Ratio =50.4. Sensitivity of TVS 54.5%, Specificity of TVS 97.6% Positive predictive value 75%, Negative predictive value 94.3%. Incidence of preterm delivery was more in women with visible membranes at time of cerclage compared to women without visible membranes at time of cerclage (100% vs. 33.3%). Relative risk of preterm delivery in women who had previous history of 2nd trimester abortions and had cervical length ≤25mm on TVS was 4. Odds ratio =11.33 Chi-square value =3.91, P=0.047 and hence significant. In women with history of previous preterm deliveries; 6(75%) women had cervical length ≤25mm on TVS; out of which 3 (50%) women delivered preterm (<37weeks). Mean gestational age at birth in group A was 38.94±2.3 weeks while in group B; it was 35.3±3.2 weeks. Relative risk of preterm delivery (≤32 weeks) in women with cervical length ≤25mm on TVS was 5.56. Relative risk of preterm delivery (≤32 weeks) in women with ≤20 mm cervical length on TVS was 8.90. In group A; out of 10 preterm babies 50% required NICU care. Term babies were 168 and 2.4% required NICU care. In group B; 11(68.8%) babies were preterm out of which 36.4% babies required NICU care. Mean birth weight was lower in group B (2.3kg) compared to group A (2.8 kg). There were no neonatal deaths in group A. There was one (6.3%) neonatal death in group B. There was one (0.6%) still birth in group A and one (6.3%) still birth in group B. Mean birth weight in cerclage group=2.4±0.8kg. Mean birth weight in without cerclage (group B)=2.1±0.14kg. DOI: 10.14260/jemds/2015/925