It is plausible that these observations are due to the fact that ultrasound measurement of the fetal zone provides a noninvasive tool to study an essential component of the physiology that initiates the preterm birth process," he said.
The fetal zone makes up the majority of the adrenal cortex in fetuses, but begins to disappear the first few days after birth.
In the current analysis, 3-D ultrasound with virtual organ computer-aided analysis technology was used to determine corrected adrenal gland volume, and 2-D ultrasound was used to measure the whole gland and fetal zone in singleton pregnancies, in 62 women presenting with preterm labor symptoms at 23-37 weeks' gestation.
In the whole population, mean depth of fetal zone enlargement was 46%, mean corrected adrenal gland volume was 400 [mm.
The depth of fetal zone enlargement was 58% in the group who were delivered within 7 days of initial assessment, compared with 40% in the group who were delivered more than 7 days after assessment.
In receiver operating characteristic area under the curve analyses, the sensitivity and specificity of fetal zone depth was 100% and 88% in the earlier and later delivery groups, compared with 85% and 90% for adrenal gland volume and 56% and 57% for cervical length.