Doppler-duplex ultrasound in renal colic.

OBJECTIVE: To determine the role of intrarenal Doppler ultrasound (US) in patients with renal colic and to establish the usefulness of this diagnostic method.

MATERIALS AND METHODS: In 121 patients with renal colic and 70 healthy individuals, 382 kidneys were examined with color duplex US. Mean intrarenal-arterial resistive index (RI), and the difference of mean RIs (dRI) between both kidneys were determined. In 64 patients, RI and dRI were compared with urographic findings (time of delay pyelogram between both kidneys).

RESULTS: In the 70 healthy individuals, RI was 0.62 +/- 0.045 and dRI 0.018 +/- 0.01. In the 121 patients with renal colic, RI (0.71 +/- 0.06) was significantly superior (P < 0.001) with respect to the opposite kidney, with a dRI of 0.09 +/- 0.055. In a correlation performed in 64 patients with urographic findings among color doppler US, with a RI > or = 0.70 and/or dRI > or = 0.06 as an indicative value of obstruction, sensitivity and specificity were 91.8% for patients with delayed pyelogram (n = 37 patients), and 48.1% for patients with nondelayed pyelogram (n = 27 patients) with a specificity of 92.8% with respect to the group of normal patients. In the group of patients with delayed pyelogram, RI was significantly superior (P < 0.05) in patients with an evolution time greater than 24 hours, in patients with proximal ureteral obstruction and in patients who had signs of pyelonephritis. There were no significant differences in the group of patients with nondelayed pyelograms.

CONCLUSION: Color Doppler US is useful to fundamentally evaluate the consequences of the obstruction on renal function. Other factors such as evolution time of the symptomology, obstruction level, or existence of pyelonephritis can alter the US-Doppler values.