Ultrasonographic Fetal Adrenal Gland Measurement for Predicting Labor Induction Success

Pregnancy progression beyond term increases the risk for perinatal morbidity and mortality. To mitigate the complications associated with post-term pregnancy, labor induction is routinely performed between 40 and 41 weeks of gestation - in accordance with protocol. However, labor induction has drawbacks – necessitating the identification of women at high risk of induction failure to prevent the associated morbidities.

A new study examined the role of ultrasonographic fetal adrenal gland enlargement in predicting the success of labor induction––among primigravida beyond 40 weeks gestation.

This study included low-risk primigravidas beyond 40 weeks gestation, scheduled for labor induction. Fetal adrenal gland dimensions were measured using an abdominal probe, such as Philips HD 7XE and general electronics logiq P6 pro, or any ultrasound machine equipped with a 7.5–10 MHz linear array probe and 3.5–5 MHz curved array probe.

The findings revealed statistically significant differences in fetal adrenal gland length, width, and ratio between the groups with successful and failed inductions. A fetal zone ratio exceeding 0.36 emerged as a cutoff with 90% sensitivity, 89% specificity, 93% positive predictive value (PPV), and 75% negative predictive value (NPV) for predicting successful induction.

Therefore, fetal zone enlargement – specifically a fetal zone ratio exceeding 0.36, proved to be a robust predictor of successful labor induction compared to traditional parameters like TVL and Bishop’s score. This parameter can be employed for screening women at risk of labor induction failure in selecting appropriate candidates for successful labor induction.

Source: Sharma R, Kumari A, Tandon A, Suneja A, Guleria K. The Journal of Obstetrics and Gynecology of India. 2023 Oct;73(5):406-13.