A comparative study of ultrasonography (USG) and computed tomography for detecting ureteric calculi in patients with acute flank pain, and analysis of factors influencing ultrasound detection rates

Abstract

Introduction: Urolithiasis, a frequent urologic issue, often relies on computed tomography (CT) scans, the preferred imaging technique. However, in low-income countries like Nepal, access to CT scans is limited. The authors’ study focused on comparing ultrasound (US) and CT for assessing ureteric calculi in patients with acute flank pain and examined factors influencing US detection rates in these patients. Methods: The authors conducted a cross-sectional study using purposive sampling, involving 87 participants who presented with acute flank pain at a tertiary hospital in Nepal. Ethical clearance was obtained from the institutional review board. Results: Among the 87 patients presenting with acute flank pain, the majority were male (51, 58.62%). Of the 78 cases with CT-detected ureteric calculi, the most common locations were distal ureter (23/78, 29.49%), followed by proximal ureter (21/78, 26.92%), and pelvic-ureteric junction (PUJ) (20/78, 25.64%). Ultrasound demonstrated varying sensitivities for detecting ureteric calculi: 95.00% for PUJ, 100.00% for vesicoureteric junction (VUJ), 66.67% for proximal ureter, and 56.52% for distal ureter calculi. The highest sensitivity was observed for calculi greater than 15 mm (100%), followed by 10.1–15 mm (77.7%). Overall, ultrasound exhibited a sensitivity of 76.92%, a specificity of 100%, and an accuracy rate of 79.31% in detecting calculi. Notably, patients with hematuria had significantly higher odds of ultrasound-detected ureteric calculi (odds ratio: 36.68, 4.54–296.26, P<0.01) than those without hematuria. However, age, hydronephrosis, calculi location, and laterality were not found to be significantly associated with ultrasound detection. Conclusions: Due to its good sensitivity, ultrasound can serve as the first-line investigation for individuals experiencing acute flank pain, given its cost-effectiveness and radiation-free nature when compared to CT scans. CT scans should be reserved for patients exhibiting clinical symptoms of severe ureteric colic who have previously undergone a negative ultrasound (USG).