Analysis of Renal Artery Hemodynamics in Normal Fetuses Using the Color Doppler Method

Abstract

Objective: From analysis of fetal renal artery hemodynamics, we attempted to reveal renal glomerular and tubular function in normal fetuses during pregnancy. Design: The study included 36 cases of normal fetuses from the 20th to the 40th week of gestation; V_max (the systolic peak velocity of main renal artery), V_mean (time averages of trace of peak velocity) blood flow were initially measured between 20 and 24 weeks of gestation and every 4 weeks thereafter. The measurement was performed a total of five times in a longitudinal study. In addition, the blood flow waveform was concurrently examined. Results: The V_max was 22.02 ± 0.50 cm/s at 20–24 weeks of gestation. This standard value (100%) was found to increase for each group as follows: 125.2, 149.1, 156.1, and 181.5%. Furthermore, using 20–24weeks of gestation as the standard, the V_mean increased after the 37th week of gestation: 186.7%, respectively. At 20–24 weeks of gestation, the blood flow wave forms consisted of 43.2% type I (only systolic waveforms), and 56.8% type II (both systolic and diastolic waveforms). Type III waveforms (waveforms that extended beyond the diastolic to the next systolic component) were not recognized. In the 33- to 36-week group, 82.6% of the waveforms were type II, and in the 37- to 40-week group, 76.2% of the waveforms were type III. Conclusions: The V_max and V_mean of the renal artery in normal fetuses exhibit a similar rate increase when 20–24 weeks of gestation is compared to 37–40 weeks of gestation. The blood flow waveforms changed as pregnancy progresses; thus, it was inferred that this finding was related to the development of the renal glomerular and renal tubular function.

Longitudinal reference intervals for Doppler velocimetric parameters of the fetal renal artery correlated with amniotic fluid index among low‐risk pregnancies

“…The trends for specific gestational ages were in agreement with other studies [10,15,16], although the absolute values differed.…”

Doppler waveform patterns and reference ranges of fetal renal artery blood flow indices in normal Thai fetuses during the second trimester

“…Most of them were type III. This finding is similar to the previous studies [4,9], which found that all 3 patterns of renal artery Doppler can be seen among normal fetuses, although the percentages of such patterns differed from those in our study. An explanation may lie in the differences in gestational age in each study and the small sample size in previous studies.…”

“…An explanation may lie in the differences in gestational age in each study and the small sample size in previous studies. Most of cases in previous studies were fetuses in the third trimester of pregnancy [4,9]. Interestingly, we found that during the second trimester of pregnancy the fetal artery Doppler indices, including of PI, PSV, S/D and RI (with AEDV removed), each increased significantly with gestational age, but the increase in EDV (with AEDV removed) with gestational age was not significant.…”

“…Moreover, the fetal and maternal outcomes were followed until delivery to confirm normal pregnancy outcome. A few previous studies have presented normal values of renal artery Doppler flow [3][4][5][6][7][8][9], but the current study is the first to include fetuses in the early second trimester of pregnancy and to have a large sample size. We chose to initiate the fetal renal artery Doppler assessment in the early second trimester because the fetal renal pathologic presentation starts at this time, so reference data on the normal renal artery is required [10].…”

Fetal Hemodynamics and Fetal Growth Indices by Ultrasound in Late Pregnancy and Birth Weight in Gestational Diabetes Mellitus

“…[10] The fetal middle cerebral artery (MCA) can directly reflect blood circulation of the fetal brain, and the S/D, PI, and RI are the hemodynamic indices of brain circulation. [11] The fetal renal artery (RA) also tends to directly reflect blood perfusion of the fetal kidney. The RA is one of the organs sensitive to hypoxia and one of the first organs to have endothelial dysfunction.…”