Delivery prediction in pregnant women with spontaneous preterm birth using fetal adrenal gland biometry.

Objective: To assess the prediction of delivery within 7 days in pregnant women who showed symptoms of spontaneous preterm birth (PB) by means of fetal adrenal gland biometry and to compare these predictions with the cervical length (CL) measurement.

Methods: We performed a prospective cross-sectional study with 53 pregnant women between 24 and 36 weeks of gestation. An ultrasound exam was performed for each participant to obtain the CL measurement (transvaginal route) and fetal adrenal gland biometry on day 1 of their hospital admission because of symptoms of spontaneous PB. The main outcome measure was the time between the ultrasound exam and delivery, which was classified into two groups: delivery  ≤7 days and delivery  >7 days. A receiver operating characteristics (ROC) curve was performed to define the cutoffs for sensitivity and specificity.

Results: The prevalence of delivery within 7 days was 35.8%, which showed a statistically significant difference from the depth of the central zone of the fetal adrenal gland (p  =  0.036). The cutoff for the depth of the central zone of the fetal adrenal gland was 7.2 mm (sensitivity 66.7%, specificity 61.8% and accuracy 63.5%). These values were not significantly different than the cutoffs for cervical length measurement: 20 mm (p  =  0.267) and 9 mm (p  =  0.118).

Conclusion: The biometry for the central zone of the fetal adrenal gland predicted delivery within 7 days in pregnant women with spontaneous PB and had a predictive accuracy similar to that of CL measurement.