RESISTANCE AND PULSATILITY INDEXES IN ACUTE RENAL OBSTRUCTION

Purpose. The aim of this study was to evaluate the reliability of Dopp ler waveform alterations in diagnosing acute unilateral renal obstruct ion. Methods. From December 1993 to January 1996, 54 patients with uni lateral renal obstruction were prospectively examined by conventional and duplex Doppler sonography. Seventy-eight patients with nonrenal ab dominal problems comprised the control group. Doppler signals were obt ained from interlobar arteries and arcuate arteries at the corticomedu llary junction. From the waveform analysis, we calculated resistance ( PI) and pulsatility (PI) indices. We also used the differences in RI a nd PI between the 2 kidneys in the same examinee (Delta RI and Delta P I) for further statistical analysis. Results. The mean RI and PI (+/- standard deviation) in the patients without renal impairment were 0.64 +/- 0.04 and 1.14 +/- 0.14, respectively. The mean Delta RI and Delta PI were 0.02 +/- 0.01 and 0.07 +/- 0.05, respectively. Both the RI an d PI were significantly correlated with age (r = 0.74 and 0.69, respec tively; p < 0.01). Acute renal obstruction significantly (p < 0.01) el evated the mean RI (0.72 +/- 0.04), Delta RI (0.09 +/- 0.04), PI (1.42 +/- 0.17), and Delta PI (0.33 +/- 0.18). Significant decreases in RI and Delta RI were noted after relief of the obstruction. The best accu racy in diagnosing acute unilateral renal obstruction was achieved wit h the combination of Delta RI greater than or equal to 0.06 and/or Del ta PI greater than or equal to 0.20, which had a sensitivity of 94% an d specificity of 99%. Conclusions. Renal Doppler indices are reliable parameters in the sonographic diagnosis of acute unilateral obstructiv e uropathy. (C) 1998 John Wiley & Sons, Inc.