Fetal adrenal and middle cerebral artery Doppler velocimetry in high-risk pregnancy

Objectives Animal studies have shown that hypoxic fetuses redistribute thei r blood flow, giving preferential supply to the brain, heart and adrenal gl ands. The aim of this study was to establish whether blood velocity wave-fo rms in the human fetal adrenal artery and middle cerebral artery showed sig ns of redistribution of fetal circulation in high-risk pregnancy, and to an alyze the relationship between signs of such redistribution and the outcome of pregnancy. Methods Fetal middle adrenal artery and middle cerebral artery waveforms we re recorded between 27 and 41 weeks of gestation in 102 pregnancies complic ated by pregnancy-induced hypertension. Signs of fetal adrenal-sparing were deemed present when the pulsatility index (PI) fell below the fifth percen tile of the normal range. Signs of fetal brain-sparing were deemed present when the cerebral artery PI was below the mean -2 SD of the normal range an d the cerebroplacental PI ratio was < 1.08. Results Signs of adrenal sparing were found in 64 cases and brain sparing i n 32 cases. Fetal adrenal sparing was strongly associated with adverse peri natal outcome; all perinatal mortality cases showed signs of adrenal sparin g. There was a significant positive correlation between the fetal adrenal a rtery PI and umbilical arterial and venous pH. Conclusions Signs of adrenal sparing are frequent in high-risk pregnancies. Adrenal artery velocimetry may be a useful procedure for fetuses at risk f or hypoxemia.