Zone-specific reference ranges of fetal adrenal artery Doppler indices:
a longitudinal study
Abstract
Objective: To establish reference ranges of adrenal artery Doppler
indices for the the inferior adrenal artery (IAA) and middle adrenal
artery (MAA). Design: longitudinal observational study Setting:China
Population or sample: 168 low-risk singleton pregnant women and their
fetuses (85 male and 83 female) with 843 observations Methods: The
pulsatility index (PI), resistance index (RI), and systolic:diastolic
ratio (S/D) of the IAA and MAA were obtained serially at 4-week
intervals. Gestational age-associated reference ranges were established
by multilevel modeling. Differences in Doppler indices between the IAA
and MAA were assessed. Main outcome measures: fetal adrenal artery
Doppler Results: Longitudinally established percentiles of Doppler
indices show that the IAA had a reduction around 35 weeks of gestation
and that the MAA remained unchanged throughout the second half of
pregnancy. The IAA had a higher detection rate than the MAA (100% vs
89.2%, p<0.05). Lower PI, RI and S/D were observed in the MAA
than in the IAA (p<0.05) from 752 paired measurements.
Conclusion: Reference ranges for adrenal artery Doppler indices that are
based on longitudinal observations appear to be more appropriate for
serial evaluation of fetal hemodynamics. There is a zonal difference in
blood supply in favor of the fetal zone, which may correspond to its
unique function, i.e., androgen secretion to help produce estrogens and
maintain pregnancy. Funding: This study was supported by the State
Natural Sciences Foundation of China (nos. 81871372,81501497).
Keywords:fetal; adrenal; doppler; pulsatility index