Fetal adrenal gland: Total gland volume and fetal zone to total gland ratio as markers of small for gestational age.

ABSTRACT

PURPOSE: Fetal adrenal gland changes have previously been investigated as novel markers of preterm labor and small for gestational age (SGA) fetuses. We aimed to compare the fetal adrenal gland parameters in SGA and appropriate for gestational age (AGA) fetuses. METHODS: A prospective cohort study was conducted on SGA fetuses with estimated fetal weight (EFW) ≤10th centile and AGA (EFW >10th centile) at 17 to 34 weeks gestation. Fetal adrenal total gland volume (TGV), TGV corrected for EFW (cTGV), fetal zone volume (FZV), FZV corrected for EFW (cFZV), and FZVTGV ratio were compared and correlated with gestational age and EFW. Receiver operator curves assessed FZVTGV ratio, cTGV, and cFZV in detecting SGA. RESULTS: Ultrasound examinations from 103 AGA and 50 SGA fetuses showed that (a) SGA fetuses had higher TGV (P = .002), FZV (P = .001), and FZVTGV (P = .036) compared to AGA fetuses; (b) fetal adrenal TGV, FZV, cFZV, and FZVTGV increase with advancing gestational age and EFW while cTGV does not; (c) Fetal adrenal changes in cTGV, cFZV, and FZVTGV have ability to differentiate SGA; (d) FZVTGV ratio 10 and 25 may be used to identify or exclude SGA in antenatally suspected SGA. CONCLUSIONS: We investigated the concept that SGA fetuses have measurable changes to the adrenal gland. We have shown that fetal TGV, TGV, and FZVTGV ratio show differences between AGA and SGA with TGV remaining significant after accounting for GA at scan. These findings may be useful as potential biomarkers for diagnosing or excluding SGA.