Interlobar venous flow is different between left and right kidney in uncomplicated third trimester pregnancy.

ABSTRACT

AIM: To investigate Doppler flow patterns of renal interlobar veins (RIV) in left (L) and right (R) kidney in relation to gestational age and to intrarenal pyelocalyceal diameters (PCD). METHODS: Cross-sectional study involving 6 groups of women (1) non-pregnant women, women pregnant between weeks (2) 11-14, (3) 18-23, (4) 28-33, (5) 37-40 and (6) women <5 days post delivery. During standardized renal duplex ultrasound scan, PCD (mm) was measured and venous impedance index (VI = [peak flow (PV) - presystolic flow]/PV) of RIV was defined. Comparison between L and R kidney was performed by repeated-measures analysis of variance for VI and by t tests for PCD. RESULTS: A total of 150 women were examined, 25 in each group. In the early third trimester of pregnancy, L VI was significantly higher than R VI (0.38 +/- 0.01 vs. 0.33 +/- 0.01, p < 0.0001) and L PCD was significantly lower than R PCD (3.90 +/- 3.68 vs. 6.25 +/- 4.03, p = 0.03). CONCLUSION: RIV Doppler flow is different between left and right kidney only in the third trimester of pregnancy. This difference is inversely related to PCD, which may be explained by pelvic compression from the gravid uterus.