Fetal Adrenal Gland Ultrasound Parameters in Pregnancies with Fetal Growth Restriction Defined by Delphi Criteria: A...

Objective: This study compared fetal adrenal gland ultrasound parameters between pregnancies complicated by fetal growth restriction (FGR) diagnosed according to Delphi consensus criteria and gestational-age-matched normally grown controls, and interpreted their apparent discriminatory performance cautiously. Methods: This prospective single-center case-control study with a cross-sectional ultrasound assessment enrolled 60 singleton pregnancies (30 FGR, 30 controls) between 24 and 41 weeks' gestation. Controls were recruited contemporaneously from the same unit and had normal fetal biometry and Doppler findings. All examinations were performed using a Voluson E8 system by a single experienced operator; operator blinding to group status was not feasible in routine clinical practice. Standard fetal biometry and Doppler indices (umbilical artery [UA] PI, middle cerebral artery [MCA] PI, uterine artery [UtA] PI) were recorded and the cerebroplacental ratio (CPR) was calculated. Fetal adrenal assessment included the total adrenal gland volume, fetal zone (FZ) width, and middle adrenal artery (MAA) Doppler PI. Results: Maternal age, body mass index, and gestational age at scan were similar between groups (p > 0.05). Compared with controls, the FGR group had higher UA PI and UtA PI and lower MCA PI and CPR (all p < 0.001). Absolute adrenal gland volume was lower in FGR (0.46 ± 0.03 vs. 0.68 ± 0.04 cm³; mean difference -0.22 cm³, 95% CI -0.24 to -0.20; p < 0.001), and FZ width was smaller (median 4.70 vs. 6.55 mm; Hodges-Lehmann shift -1.80 mm, 95% CI -2.00 to -1.70; p < 0.001). MAA PI was higher in FGR (2.44 ± 0.14 vs. 1.79 ± 0.12; mean difference 0.65, 95% CI 0.58-0.72; p < 0.001). In this selected case-control dataset, adrenal volume, FZ width, and MAA PI each showed apparent complete separation (empirical AUC = 1.00); however, these findings should be interpreted cautiously because absolute adrenal measures were not adjusted for fetal size and such performance may reflect spectrum effects in a relatively small sample. Conclusions: In pregnancies with Delphi-defined FGR, absolute fetal adrenal volume and fetal zone width were lower, and MAA PI was higher than in controls. These findings should be considered hypothesis-generating and require external validation in larger multicenter cohorts using standardized and size-adjusted measurement approaches before clinical implementation.