[Biparietal diameter/kidney length ratio in cases with chronic hypoxic state]

The object of this study was to investigate the fetal biparietal diameter/kidney length ratio in normal and hyperechogenic kidneys during the third trimester of gestation.

The selected cases were characterized by pregnancy-associated hypertension and/or proteinuria, which was associated with fetal hypoxia due to the depression of placental blood flow. Depending on the renal manifestation of intrauterine chronic hypoxia, cases were divided into two study groups. Group I was composed of 21 fetuses with pregnancy-associated hypertension and/or proteinuria and hyperechogenic renal medullae. Group II consisted of 162 fetuses with pregnancy-associated hypertension and/or proteinuria and normal echoic kidney. Both study groups included pregnant women from the third trimester.

Fetal renal hyperechogenicity correlated with the pathological growth of fetal kidney. The fetal biparietal diameter/kidney length ratio was significantly lower in cases of hyperechogenicity.

The fetal renal hyperechogenicity is a relevant indicator of diminution of fetal renal perfusion. This can lead to abnormal development of the affected kidney and can result in a pathological reduction of biparietal diameter/kidney length ratio, which may also be an in utero indicator of subsequent intrauterine and neonatal complications. Detailed ultrasound examinations of renal parenchyma and kidney length seem to be a useful method in the prenatal diagnosis of decreased renal perfusion and of intrauterine hypoxia and serve to detect pathological conditions in utero.