Fetal renal artery flow and renal echogenicity in the chronically hypoxic state

The object of this study was to investigate the fetal renal arterial blood flow in normal and hyperechogenic kidneys during the third trimester of ges tation. The pregnancies screened were all chronically hypoxic. Depending on the etiology of the intrauterine chronic hypoxia, the cases were divided i nto two study groups. Group I comprised 120 pregnant women with pregnancy-a ssociated hypertension and/or proteinuria. Group II consisted of 87 pregnan cies with intrauterine growth retardation. Both study groups included pregn ant women from the third trimester. Hyperechogenic renal medullae were dete cted in 15 out of 120 cases with pregnancy-associated hypertension and/or p roteinuria, and in 22 fetuses of the 87 pregnancies involving intrauterine growth retardation. Fetal renal hyperechogenicity appears to be an indicato r of fetal arterial circulatory depression, correlated with pathological ch anges in the resistance index for the fetal renal arteries. The fetal renal arterial blood flow resistance index was significantly lower in hyperechog enic cases. This may also be an in utero indication of subsequent intrauter ine and neonatal complications, such as cesarean section because of fetal d istress (43%), treatment in a neonatal intensive care unit (51%) or increas ed perinatal mortality (5.4%, as compared with 0.8-1.0% in the normal popul ation). Detailed ultrasound and Doppler examinations of renal parenchyma an d arteries appear to be useful methods in the prenatal diagnosis of reduced renal perfusion and of intrauterine hypoxia to detect possible pathologica l fetal conditions in utero.