Clinical value of renovascular resistive index measurement in the diagnosis of acute obstructive uropathy.

PURPOSE: We evaluated the clinical use of the renal resistive index in identifying patients with acute urinary tract obstruction. MATERIALS AND METHODS: Of 54 patients with suspected acute urinary tract obstruction who underwent measurements of renal resistive index 19 had unilateral obstruction documented with excretory urography and comprise our study sample. The contralateral nonobstructed kidneys served as controls. Criteria for obstruction were a resistive index of 0.70 or greater or a side to side difference of 0.10 or greater. We calculated sensitivity, specificity, and positive and negative predictive values. RESULTS: Sensitivity for obstruction was 42% with 11 false-positive cases, specificity was 79%, and positive and negative predictive values were 67 and 57%, respectively. CONCLUSIONS: Renal resistive index measurements are not valuable in detecting acute urinary tract obstruction.