Evaluation of Acute Partial Unilateral Ureteral Obstruction Based on the Renal Venous Impedance Index in Rabbit: An Experimental Study

In contrast to complete ureteral obstruction; evaluation of venous flow and its comparison with arterial flow has not been performed in acute partial unilateral uretral obstruction (APUUO) via renal Doppler indices. In this study it was aimed that to measure changes in intrarenal venous flow compared to arterial flow and to investigate the feasibility of the venous impedance index (VII) in the diagnosis of APUUO. In New Zealand rabbits (n=10) the left ureter was narrowed by ligation. Doppler ultrasonographic (US) examination of the interlobar arteries and veins in both kidneys was performed preoperatively and 3, 6, 12, 24 and 48 h after ureteral ligation. Resistive index (RI) difference (RIΔ) and the RI ratio (RIr) were calculated from RI obtained from the obstructive and nonobstructive kidneys. The RI and VII were compared between the left and right kidneys at all intervals. Although the mean RI for obstructive kidneys were higher than those for nonobstructive kidneys, the difference was only statistically significant at 3 and 24 h (P=0.007, and P=0.049, respectively). RIΔ was ≥0.08 and RIr ≥1.169 at all postoperative time points. The mean VII values were significantly lower in the obstructive kidneys than the nonobstructive kidneys at all time points (P≤0.001). Venous flow was more affected than arterial flow in the obstructive kidney. Although the renal RI alone was determined to be insufficient as a diagnostic criterion, decreased unilateral renal VII can enhance the diagnostic accuracy of in APUUO if used with the RIΔ and RIr.