RENAL RESISTIVE INDEX IN EXPERIMENTAL PARTIAL AND COMPLETE URETERAL OBSTRUCTION

Rationale and Objectives. Recent clinical work suggests that the Doppl er resistive index (RI) may be useful in distinguishing obstructive fr om nonobstructive hydronephrosis. We evaluated the usefulness of the R I in a rabbit model of hydronephrosis. Methods. Unilateral partial ure teral obstruction was produced in nine rabbits and complete obstructio n in another nine. Three sham operations were performed, and these ani mals served as control subjects. The RI was measured in all kidneys be fore and 6 hr after surgery and on days 1, 4, and 7 postoperatively. T he RI and the difference in RI (Delta RI) between the obstructed and n ormal kidney were evaluated over lime using a two-way analysis of vari ance. The intravenous urography and Whitaker tests served as gold stan dards. Results. Hydronephrosis was observed on sonograms in all obstru cted kidneys. Comparing groups, there was no significant difference in mean RI or Delta RI between the three groups at any time point, Looki ng at individual groups over time, there was no significant change in mean Delta RI, whereas the change in mean RI was significantly elevate d above baseline only in the complete obstruction group at 6 hr (p = . 002) and on days 4 (P = .008) and 7 (p = .006). In evaluating varying thresholds of RI and dRI, we could not consistently discriminate betwe en normal and obstructed kidneys. Conclusion. Although complete obstru ction caused a significant increase in RI, partial obstruction failed to do so. RI and Delta RI values proved to be insensitive predictors o f obstruction in this rabbit model.