Doppler sonography in acute renal obstruction

Abstract

Aims and Objectives: This prospective analysis was carried out to study the utility of Doppler waveform alterations in the diagnosis of unilateral acute renal obstruction and to study the factors affecting Doppler indices. Methods: In this prospective analysis between May 2005 and March 2006, patients presenting to the emergency medical division with symptoms of unilateral acute renal colic underwent Doppler analysis. Obstruction was confirmed by intravenous urography (IVU) or computed tomography (CT) scan. The duration of renal colic and the site and degree of obstruction were recorded. Patients with medical or surgical renal disease were excluded. Results: 40 patients (80 kidneys) satisfying the inclusion criteria were part of this analysis. The mean resistivity Index (RI) in obstructed kidneys was significantly higher than in the contralateral unobstructed kidneys (0.72 Vs 0.64; p < 0.001). Thirty (75%) cases had proximal while 10 (25%) cases had distal obstruction with higher RI in proximal obstruction (0.73 Vs 0.72). Twenty-five (62.5%) patients had complete, while 15 (37.5%) patients had partial obstruction. The RI value in completely obstructed kidneys was significantly higher than in partially obstructed kidneys (0.74 Vs 0.70; p < 0.05). Using the discriminatory value of 0.70 for obstruction, the overall sensitivity was 87.5% and specificity 90%. Sensitivity was 95% and specificity 100% at a delta RI of 0.06. The degree of obstruction altered the resistivity indices, while the site of obstruction and duration of symptoms did not. Conclusions: Doppler sonography is a useful diagnostic tool in unilateral acute renal obstruction.

Keywords

• Doppler sonography
• resistivity indices
• unilateral acute renal obstruction