Fetal renal blood flow assessment by three‐dimensional power Doppler ultrasound: preliminary results of a three‐dimensional histogram study

Abstract

Purpose: To assess the fetal renal blood flow in normal gestation using three‐dimensional (3D) power Doppler ultrasound.Methods: The study was under a prospective, consecutive and cross‐sectional design. Normal pregnancies that attended the prenatal clinic were included. We used a three‐dimensional power ultrasound scanner, Voluson 530D MT (Kretz, Zipf, Austria) to assess the total blood flow of fetal kidney. First, we used the 3D transabdominal probe to scan the whole fetal kidney under the 3D power Doppler mode at a fixed condition. Second, we used the VOCAL software (Kretz, Zipf, Austria) to calculate the histogram indices of fetal renal blood flow obtained from the 3D power Doppler scanning. The histogram indices included vascularization index (VI), flow index (FI) and vascularization‐flow index (VFI).Results: In total, 81 fetuses ranging from 20 to 39 weeks of gestation were included for final analysis. Our results showed that VI had a high correlation with gestational age (r = 0.90, n= 81, P < 0.001). In addition, FI was positively correlated with gestational age (r = 0.35, n= 81, P < 0.05), and VFI also presented a high correlation with gestational age (r = 0.88, n= 81, P < 0.001). Furthermore, the VI, FI, and VFI of fetal kidney in the third trimester were all higher than those indices of fetal kidney in the second trimester (all P < 0.01).Conclusion: The 3D power Doppler ultrasound can assess the total blood flow of fetal kidney, which is superior to the previous methods of blood flow assessment. Our study indicates that fetal renal flow increases with the advancement of gestational age, and our data may be a useful reference for further studies of fetal renal flow in abnormal conditions.