Doppler sonography in the diagnosis of urinary tract obstruction by stone

PURPOSE: This study was conducted to evaluate the accuracy of Doppler sonography in renal colic due to obstruction and to assess whether the resistance index (RI) and interrenal RI difference (DeltaRI) are time-dependent parameters. SUBJECTS AND METHODS: Obstructed and unobstructed contralateral kidneys in 28 patients with renal colic and normal kidneys in 27 control subjects were prospectively evaluated with Doppler sonography. Mean RI, mean DeltaRI, and duration of pain were evaluated. Statistical analysis was done using paired and independent t-tests. RESULTS: Mean RIs of the control-group, obstructed, and contralateral kidneys were 0.60, 0.71, and 0.61, respectively; mean DeltaRI values of the obstructed and control-group kidneys were 0.10 and 0.03, respectively. Differences in mean RI between obstructed and contralateral or control-group kidneys were statistically significant (p < 0.001). There was a statistically significant difference in DeltaRI between patients and controls (p < 0.001). The difference between the RI values of kidneys with low-grade (0.70) and high-grade obstructions (0.72) was not statistically significant. The difference between the DeltaRI values of kidneys with low-grade (0.08) and high-grade obstructions (0.13) was statistically significant (p < 0.05). Differences in the mean RI and mean DeltaRI values between 3 groups of patients categorized according to the duration of pain were not statistically significant. CONCLUSIONS: Along with gray-scale sonography and intravenous urography, Doppler sonography can be used in the evaluation of renal obstruction. RI and DeltaRI are not time-dependent parameters.