Diagnostic Accuracy of Renal Artery Resistive Index in Diagnosing Obstructive Uropathy

Abstract

Background: Obstructive uropathy, a common cause of acute and chronic kidney disease, poses diagnostic challenges, particularly when non-invasive methods are preferred to reduce patient exposure to ionizing radiation from CT scans. The renal artery resistive index (RI) measured by Doppler ultrasound presents a potential non-invasive diagnostic tool, yet its accuracy and utility in clinical practice require further elucidation. Objective: To assess the diagnostic accuracy of the renal artery resistive index (RI) as measured by Doppler ultrasound in identifying obstructive uropathy, using CT scans as the gold standard for comparison. Methods: This cross-sectional study included 201 patients presenting with symptoms indicative of obstructive uropathy at a tertiary care hospital. Participants underwent both Doppler ultrasound to measure the renal artery RI and non-contrast CT scans of the kidneys, ureters, and bladder (KUB). The diagnostic performance of the RI was evaluated in terms of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy, with CT scan findings serving as the benchmark. Results: The study cohort had a mean age of 43.02±15.62 years, with a male predominance (64.7%). The renal artery RI demonstrated a sensitivity of 81.13%, specificity of 85.81%, PPV of 67.19%, NPV of 92.70%, and an overall accuracy of 84.58% in diagnosing obstructive uropathy. Calculi were more frequently located in the right urinary tract (54.2%) than the left (45.8%), with the majority being smaller than 1 cm (79.1%). Conclusion: The renal artery resistive index (RI) measured by Doppler ultrasound is a highly accurate diagnostic tool for detecting obstructive uropathy, offering a viable, non-invasive alternative to CT scans. This method could significantly reduce unnecessary radiation exposure in patients, aligning with current healthcare priorities for safety and efficiency.