Hemodynamics of the Fetal Renal Artery in Cases of Isolated Oligohydramnios Between 35 Weeks' and 40 Weeks' Gestation

PurposeThis study aimed to describe hemodynamic changes in the fetal renal artery in cases of isolated oligohydramnios during the late 3rd trimester of pregnancy.MethodsUltrasonographic measurements of the hemodynamic parameters over the fetal renal artery were made between 35 weeks' and 40 weeks' gestation in 66 patients with isolated oligohydramnios and 60 patients with normal amniotic fluid volumes. Apart from oligohydramnios in the study group, neither the patients in the study group nor the control group had any fetal or maternal anomalies or complications. The measured parameters of hemodynamic changes over the fetal renal artery included the resistance index/pulsatility index, systolic/diastolic ratio, acceleration time, and blood flow using spectral and power Doppler modalities. In addition, fetal renal volume, birth weight, and the Apgar score were measured and recorded in both groups prior to and after delivery of the infants. The receiver operating characteristics and the two-tailed t test were used for statistical analyses.ResultsCompared with the control group, the systolic/diastolic ratio and acceleration time were higher in the isolated oligohydramnios group, but with a lower fetal renal blood flow.ConclusionOur study shows that isolated oligohydramnios is related to fetal hemodynamic changes in the fetal renal artery and the regulatory mechanisms of the vascular bed.