Ultrasonographic Measurement of Fetal Adrenal Gland Size for the Prediction of Success of Induction of Labor Among Primigravida Beyond 40 Weeks Gestation.

Introduction: As the pregnancy advances beyond term, the risk of perinatal morbidity and mortality increases. Hence to prevent these complications associated with postterm pregnancy, induction of labor is done, as per our institution protocol between 40 and 41 weeks of gestation. Induction has its own drawback, so it is essential to identify the women with high chances of failure of induction of labor, to prevent the morbidities associated with induction failure.

Aim: To study the role of ultrasonographic fetal adrenal gland enlargement for the prediction of success of labor induction among primigravida beyond 40 weeks gestation.

Material and methods: Low-risk primigravidas beyond 40 weeks gestation, scheduled for induction of labor, were enrolled for the study. Fetal adrenal gland dimensions were measured by using abdominal probe Philips HD 7XE and general electronics logiq P6 pro or any ultrasound machine equipped with 7.5-10 MHz linear array probe and 3.5-5 MHz curved array probe.

Results: The fetal adrenal gland length, width and ratio were statistically significant between the successful versus failed induction groups. The cutoff fetal zone ratio > 0.36 for the prediction of successful induction of labor had 90% sensitivity, 89% specificity, 93% PPV and 75% NPV.

Conclusion: Fetal zone enlargement (fetal zone ratio > 0.36) is a strong predictor of successful induction of labor as compared to TVL and Bishop's score. It can be used for screening the women, who are destined for induction failure, so that adverse effects of induction of labor can be avoided.