It’s proposed that oligohydramnios is caused by decreased renal perfusion due to redistribution of fetal blood at fetal growth restriction. Isolated oligohydramnios refers to the presence of oligohydramnios without fetal structural and chromosomal abnormalities, without fetal growth restriction, without intrauterine infection, and in the absence of known maternal disease. It’s unknown whether the redistribution or decreased renal perfusion cause isolated oligohydramnios. The aim of the study was to evaluate fetal renal artery Doppler blood velocimetry and cerebro-placental ratio (CPR) among women with isolated oligohydramnios between 25–40 weeks of gestational age.

The middle cerebral artery, umbilical artery and, renal artery pulsatility index (PI) values were measured in 45 fetuses with isolated oligohydramnios and 65 fetuses with normal amniotic fluid. Oligohydramnios was defined as deepest vertical amniotic fluid being measured lower than 1cm. The CPR (middle cerebral artery PI/umbilical artery PI) and renal artery PI values were expressed as multiples of the normal median (MoM) and were compared between the two groups.

There was no difference in MoM of CPR PI (p=0.167) and MoM of renal artery PI values (right p=0.253, left p=0.353) between the groups.

The renal artery Doppler velocimetry and CPR were not significantly different in the women with isolated oligohydramnios, compared to the women with normal amniotic fluid.