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

Abstract

The object of this study was to investigate the fetal renal arterial blood flow in normal and hyperecho-genic kidneys during the third trimester of gestation. The pregnancies screened were all chronically hypoxic. Depending on the etiology of the intrauterine chronic hypoxia, the cases were divided into two study groups. Group I comprised 120 pregnant women with pregnancy-associated hypertension and/or proteinuria. Group II consisted of 87 pregnancies with intrauterine growth retardation. Both study groups included pregnant women from the third trimester. Hyperechogenic renal medullae were detected in 15 out of 120 cases with pregnancyassociated hypertension and/or proteinuria, and in 22 fetuses of the 87 pregnancies involving intrauterine growth retardation. Fetal renal hyperechogenicity appears to be an indicator of fetal arterial circulatory depression, correlated with pathological changes in the resistance index for the fetal renal arteries. The fetal renal arterial blood flow resistance index was significantly lower in hyperechogenic cases. This may also be an in utero indication of subsequent intrauterine and neonatal complications, such as cesarean section because of fetal distress (43%), treatment in a neonatal intensive care unit (51%) or increased perinatal mortality (5.4%, as compared with 0.8-1.0% in the normal population). Detailed ultrasound and Doppler examinations of renal parenchyma and arteries appear to be useful methods in the prenatal diagnosis of reduced renal perfusion and of intrauterine hypoxia to detect possible pathological fetal conditions in utero.

Fetal Renal Volume and Fetal Doppler in Normal and Growth Restricted Fetuses: Is there a Correlation?

“…Using three-dimensional US systems with VOCAL method gives a good agreement with true kidney volumes [20,21]. However, 3-dimensional US for kidney volume estimation are limited by high cost of the equipment.…”

Correlation Between Fetal Renal Volume and Fetal Renal Doppler in Normal and Growth Restricted Fetuses : An Initial Experience

“…Most accurate method is by three dimensional ultrasound with VOCAL method and most widely acceptable. (18,19) However doing three-dimensional ultrasound for kidney volume is not cost effective and hence we preferred doing two dimensional ultrasound in our study to calculate fetal renal volume which was more feasible and more or less precise.…”

What is biparietal diameter/kidney length ratio in cases with renal hyperechogenicity?

“…Ultrasonographic determination of biparietal diameter/kidney length ratio in utero is the preferred method for evaluation of intrauterine hypoxia. It is well documented that fetal renal hyperechogenicity is an indirect sign of intrauterine hypoxia [10,11,12] (Fig. 2).…”

“…Fetal renal hyperechogenicity with no anatomical alteration is the indirect sign of intrauterine hypoxia (e.g. IUGR) [9,10,11,12,13]. Therefore, we measured biparietal diameter/kidney length ratio with ultrasonography in fetuses to establish whether the renal hyperechogenicity correlates with pathological size in IUGR due to intrauterine hypoxic conditions.…”

“…The gestational age was calculated according to Naegele's rule and the 1st trimester ultrasound examination. IUGR was established by Hansmann's weight estimation, based on biparietal and transverse trunk diameters [14,15,16].…”