Transrectal ultrasonography of distal ureteral calculi: comparison with intravenous urography.

In a prospective fashion, transrectal ultrasonography and intravenous urography were performed in 48 patients with distal ureteral calculi. We compared the ability of the two modalities to detect calculus and to determine the size of the calculus, the degree of obstruction, and the degree of hydroureter. In 11 cases (23%), the calculus was not seen at intravenous urography, while transrectal ultrasonography detected calculus in each patient. In 37 cases in which calculi were detected by both modalities, the average diameter of the calculus determined by ultrasonography was significantly larger (P < 0.05) than that obtained by plain radiography. Positive correlations were obtained in the assessment of degree of obstruction (correlation coefficient = 0.587, P < 0.05) and hydroureter (correlation coefficient = 0.794, P < 0.05) between the two techniques. Transrectal ultrasonography appears to be a useful adjunctive method to evaluate distal ureteral calculus, particularly if the results of intravenous urography are inconclusive.