Inferior adrenal artery PI in fetuses with IUGR: value indicating early blood redistribution and steroidogenic response.

OBJECTIVE To characterize the inferior adrenal artery (IAA) pulsatility index (PI) in intrauterine growth-restricted (IUGR) fetuses without brain sparing. METHODS Twenty-three IUGR fetuses with a normal Doppler cerebroplacental ratio (CPR) and 23 normal controls were included in this prospective cross-sectional study. The PI of the IAA was recorded using routine transabdominal Doppler ultrasound. The differences in Doppler characteristics, perinatal outcomes and steroidogenesis in the umbilical vein at birth (adrenocorticotropic hormone (ACTH) and cortisol (F) levels) were compared between the two groups. The correlations between IAA-PI and steroidogenesis were assessed in the IUGR group. RESULTS IAA-PI was significantly lower in IUGR fetuses than in normal controls (0.85 vs 1.18 at fisrt scan, 0.78 vs 0.92 at last scan, both p<0.001). The plasma F and ACTH levels in IUGR cases were significantly higher than those of the normal controls (18.2 vs 12.4 µg/dl and 280.5 vs 125.6 pg/ml for F and ACTH, respectively; both P<0.001). There were negative correlations between IAA-PI and plasma F values and between IAA-PI and ACTH values in the IUGR group (r=-0.774 and -0.82 at first scan, r=-0.525 and -0.45 at last scan, respectively; P<0.001). CONCLUSION Increased adrenal gland blood flow with concomitant increases in ACTH and F levels were observed in IUGR fetuses. IAA-PI is useful to assess early blood redistribution and may be beneficial for evaluating the steroidogenic response in high-risk pregnancies.