The Accuracy of Transvaginal Ultrasound and Bishop Score to Predict the Successful Induction of Labor in Primigravidas at Term

Abstract

Objective: To determinethe accuracy of transvaginal ultrasonographic measurement of cervical length versus Bishop Score in predicting success of induction of labor in primigravida presenting at term. Methods: This comparative cross sectional study was conducted in department of obstetrics and gynecology,
Lady Aitchison Hospital, Lahore from January 2015 to July 2015. Total 220 females were included through Non probability, purposive sampling. The females underwent vaginal examination and Bishop Score was noted and case was labeled as positive or negative. Then females underwent Transvaginal Ultrasound (TVS) by researcher herself and the case was labelled negative or positive. Then females were induced by using Misoprostol (PGE1) 50 microgram and were observed for labor onset and normal delivery, All the readings were recorded on specially designed performa. Data was entered and analyzed using Statistical Package for the Social Sciences (SPSS) version 16.0. Results: The mean age of females was 27.59±7.04 years. The mean gestational age of females at time of
presentation was 41.47±0.50 weeks. There were 171 (78%) females who had bishop score >5 while 49 (22%) females had bishop score <5. There were 154 (70%) females who had cervical length <27mm while 66 (30%) females had cervical length >27mm.The mean induction to delivery interval was 23.01±4.66hours. There
were 130 (59%) females who delivered within 24 hours while 90 (41%) females who delivered after 24 hours. The calculated sensitivity, specificity, Positive Predictive Value (PPV), Negative Predictive Value (NPV) and diagnostic accuracy of Bishop score were 83.8%, 31.1%, 63.7%, 57.1% and 62.3%.The calculated
sensitivity, specificity, PPV, NPV and diagnostic accuracy of cervical length were 90%, 58.9%, 76% ,80,3% and 77.3%. Conclusion: It was concluded through results of this study that assessment of cervical length on transvaginal ultrasound has more accuracy than bishop in predicting successful induction of labor in primigravidas presenting at term,