Relation between Fetal Renal Artery Doppler ‎Indices and Non-PROM Oligohydramnios in ‎Third Trimester of Pregnancy

Background: Amniotic fluid is the liquid which surround the fetus after the first few weeks of gestation. Amniotic fluid is derived mostly from the fetus and has many functions that are essential for normal growth and development. The aim of this work is to study the relation between fetal renal artery flow velocity waveforms and amniotic fluid volume in normal pregnancies and those complicated by oligohydramnios.

Methods: This prospective observational study was carried out on 40pregnant women (10) of them were with normal amount of amniotic fluid (group I), while (30) of them suffered from oligohydramnios (group II).By using color doppler ultrasound imaging, the fetal renal circulation can be assessed. Intermittent assessment of renal artery flow velocity waveforms during the early stages of pregnancy may help in predicting changes in amniotic fluid dynamics.

Results: There was a non-significant difference between cases with normal amount of amniotic fluid and cases with oligohydramnios in Gestational age, Maternal age, fetal femur length, bi parietal diameter, abdominal circumference and Fetal weight. There were increased values of fetal renal artery Resistance index (RI) and Pulsatility index (PI) in cases of oligohydramnios than cases with normal amount of amniotic fluid. There was no correlation between Peak systolic velocity (PSV) and Amniotic fluid index (AFI). There was a significant difference in End diastolic velocity (EDV) between cases with normal amount of amniotic fluid and cases with oligohydramnios. Also, there was a significant difference in Systolic diastolic ratio (S/D) and Amniotic fluid index (AFI) between cases with normal amount of amniotic fluid and cases with oligohydramnios.

Conclusions: There is a relation between renal artery flow velocity waveforms and oligohydramnios using Pulsed wave Doppler Ultrasonography. There are higher values of renal artery Resistance index and Pulsatility index in cases of oligohydramnios more than cases with normal amount of amniotic fluid.