Doppler sonography in acute renal obstruction and role of intra venous urography: a study in a tertial care centre

Abstract

Background: Arterial RI measurements by duplex Doppler USG have been advocated for the diagnosis of obstruction. In most centres, obstruction is indicated by an RI greater than 0.70 or a difference of greater than 0.10 between the kidneys. Our aim was to evaluate and compare the Doppler waveform alterations in unilateral acute renal obstruction (UARO) with the contralateral normal kidney as a control. Methods: 100 patients presenting to the emergency medical division with symptoms of unilateral acute renal colic were subjected to USG and Doppler USG. The renal RI was calculated in comparison to the collateral normal kidney. Results: The mean resistivity index (RI) was higher in obstructed kidneys in all cases. 80% patients had complete, while 20% had partial obstruction. RI value in completely obstructed kidneys was 0.72 versus 0.71; p<0.05. However, even in partially obstructed kidneys, RI was significantly higher than in the contralateral (unobstructed) kidney. The diagnostic accuracy of the Doppler was 96% sensitive in the complete obstruction cases and 85% in patients with partial obstruction. Conclusions: Doppler USG is a useful diagnostic tool in unilateral acute renal obstruction, with RI values being significantly higher in patients with complete obstruction than in patients with partial obstruction.