Assessing Renal Hemodynamics in Acute Ureteric Obstruction Using Resistive Index on Doppler Ultrasonography: A Paired Prospective Study

Background: Acute ureteric obstruction due to calculi frequently presents as renal colic, requiring prompt diagnosis to prevent complications. While non-contrast computed tomography (CT) remains the gold standard, concerns about radiation exposure necessitate alternative diagnostic approaches. Doppler ultrasound-derived resistive index (RI) offers functional insight into renal hemodynamics when grayscale ultrasound findings are inconclusive. To evaluate the diagnostic accuracy of Doppler-derived resistive index in detecti Objective: ng acute ureteric obstruction and determine its clinical utility as a non-invasive alternative to CT imaging. This prospective observ Methods: ational study was conducted at J.J.M Medical College, Davanagere, from June to October 2024. Thirty patients aged 18-65 years presenting with unilateral acute renal colic within 24 hours were enrolled. All patients underwent grayscale and Doppler ultrasound examination using standardized protocols. Resistive index values were measured in bilateral segmental renal arteries. Statistical analysis included paired t-tests and ROC curve analysis. The study Results: included 30 patients (18 males, 12 females; mean age 42.7 years). Symptomatic kidneys demonstrated significantly higher RI values (0.75 ± 0.06) compared to contralateral kidneys (0.56 ± 0.05), with a mean paired difference of 0.19 (95% CI 0.15-0.23; p < 0.001). An RI threshold > 0.7 provided optimal diagnostic performance with an area under the curve of 0.89. Doppler-derived resis Conclusion: tive index measurement is a valuable, non-invasive diagnostic tool for evaluating acute ureteric obstruction. Its integration into clinical protocols may reduce reliance on radiation-intensive CT imaging while providing functional hemodynamic assessment.