The gap between ultrasonography and computed tomography in measuring the size of urinary calculi.

Abstract

Due to a lack of studies regarding the need for computed tomography (CT) in measuring the size of each urinary calculus before surgery, this study was conducted to elucidate the difference between ultrasonography (US) and CT in measuring the size of urinary stones. A retrospective review of 100 stones from 83 patients. Each urinary stone was measured using both US and CT; both measurements were then compared. Of 83 patients, the mean age was 39.29 ± 23.76 years; 47 (56.62%) were male and 36 (43.37%) were female. Most of the urinary stones were <10 mm (50.0%) followed by 11-20 mm (42.0%), (<i>P</i> < 0.001). A cross-tabulation test revealed strong compatibility between US and CT in measuring the size of urinary stones (73.7% in stones <10 mm, 66.7% in stones 11-20 mm and 50% in stones >21 mm), (<i>P</i> < 0.001). Spearman's rho correlation test revealed strong compatibility between stone diameters measured by US and CT (r = 0.755), (<i>P</i> = 0 < 0.001). T-test for equality of means revealed no significant difference in the measured size using US and CT (mean = 11.80 ± 5.83 vs. 11.65 ± 6.59, respectively), mean difference = 0.15, and <i>P</i> = 0.865, 95% confidence interval: -1.584-1.884. No significant difference in measuring the size of urinary stones using US and CT. However, US may slightly overestimate small stones in some cases.