Cost-effective emergency diagnosis plan for urinary stone patients presenting with ureteric colic

To develop a cost-effective plan for the accurate diagnosis of urinary stone patients presenting with ureteric colic based on an assortment of investigations which are less invasive and more economical than intravenous urography (IVU).

143 consecutive emergency patients presenting with ureteric colic were admitted to hospital and prospectively studied by history recording, physical examination, laboratory tests and imaging procedures according to a preset format. Significant association of the final diagnosis of urinary stones (which was made by actual stone retrieval) with various diagnosis variables obtained from the results of investigation (including IVU) was statistically studied using bivariate correlation and multivariate logistic regression analysis. Algorithms for reaching an accurate diagnosis of urinary tract stones were formulated using the most significant diagnostic variables and the accuracy of each of those plans was compared with that of emergency IVU.

18 patients were excluded for various reasons. Of the remaining 125 patients 82 (66%) were confirmed as having urinary stones. A positive IVU had the strongest correlation with the final diagnosis of urinary tract stones. Other findings associated with eventual stone retrieval in a descending order of significance were: calcular sonographic features; radio-opacities on a plain abdominal film of the kidney, ureter and bladder (KUB), and microhaematuria. Based on these findings two algorithms could be formulated to reach as accurate a diagnosis as possible. Algorithm A in which an initial ultrasound is mandatory had a sensitivity of 89%, a specificity of 88% and an overall accuracy of 88% for urinary stone detection compared with 91, 77, and 86%, respectively, for algorithm B in which ultrasonography was employed selectively after initial KUB and urinalysis for microhaematuria. This compares with 94, 79, and 89%, respectively, for IVU.

Both plans are viable alternatives which could replace routine emergency IVU.