Fetal renal hyperechogenicity in intrauterine growth retardation: importance and outcome.

The object of the study was to investigate the outcome in growth-retarded newborns who were diagnosed with fetal renal hyperechogenicity without anatomical abnormality during any stage of pregnancy. Depending on the fetal renal ultrasonography result, the cases were divided into two study groups. There was an intrauterine growth-retarded group with fetal renal medullary hyperechogenicity and another group without fetal renal medullary hyperechogenicity. The renal parenchyma was observed after birth, within the first 5 days of life, and several times until the 14th postpartum day in positive cases. Hyperechogenic renal medullae were detected in 25 of 90 cases with intrauterine growth retardation during the 8-month study period. This may be an in utero cause of subsequent intrauterine and neonatal complications, such as cesarean section because of fetal distress (36%), perinatal infection (24%), treatment in a neonatal intensive care unit (52%), or increased perinatal mortality (8%). The results demonstrate that fetuses with hyperechoic medullae had 1.5 times the risk of an abnormal outcome compared with fetuses with normal echoic kidneys and intrauterine growth retardation. Detailed ultrasound examinations of renal parenchyma appear to be useful for the prenatal diagnosis of intrauterine hypoxia, allowing the detection of possible pathological fetal conditions in utero.