Duplex Doppler sonography in patients with acute renal colic: Prospective study and literature review

PURPOSE: To determine the value of duplex Doppler sonography in the diagnosis of acute urinary obstruction. MATERIALS AND METHODS: In 46 healthy individuals and 42 patients with urinary obstruction confirmed by intravenous urography, 176 kidneys were examined with duplex Doppler sonography. The mean intra-arterial resistive index value and the difference of mean resistive index values between both kidneys were determined for each person. Resistive index and delta resistive index values were compared with urographic findings in the 42 patients. RESULTS: In the 46 healthy individuals, the mean resistive index and delta resistive index values were 0.59 +/- 0.05 and 0.03 +/- 0.01. In the 14 patients with complete urinary obstruction, these values were 0.70 +/- 0.06 and 0.09 +/- 0.02, whereas in the 28 patients with partial urinary obstruction, these values were 0.64 +/- 0.06 and 0.03 +/- 0.05. Urographic findings and duplex Doppler sonography were correlated in the 42 patients, with a resistive index = 0.65 and delta resistive index = 0.05 as discriminatory thresholds for obstruction. In patients with complete obstruction, the diagnostic sensitivity of these values was 64% and 100% with a specificity of 82% and 89%, respectively. In patients with partial obstruction, the sensitivity of these values was 54% and 46% with a specificity of 82% and 89%, with respect to the control group of healthy individuals. CONCLUSION: Delta resistive index is a very sensitive and specific parameter in the sonographic diagnosis of complete urinary obstruction but insensitive in partial urinary obstruction. Duplex Doppler sonography is recommended in cases where intravenous urography is contraindicated.