To evaluate stone diameter and ureteral dilation using computerized tomography as a predictor of ureteral stone expulsion after medical expulsive therapy.

We retrospectively reviewed the records of 328 patients with symptomatic ureteral stones <10 mm on axial computerized tomography images, who were treated with alpha blockers for 2 weeks. Computerized tomography scans were also performed 2 weeks after medical expulsive therapy to confirm ureteral stone expulsion. Patients were divided into upper ureteral stones and lower ureteral stones above and below the iliac vessels, respectively. Transverse stone diameter and longitudinal stone diameter were defined as the largest stone diameter determined on the axial and coronal computerized tomography images, respectively. Ureteral diameter was determined on one computerized tomography slice proximal to each ureteral stone on axial computerized tomography images, and the ratio of ureter-to-stone diameter was defined as ureteral diameter divided by transverse stone diameter.

Among 328 patients, the stone expulsion rate was 44.1% in 145 upper ureteral stones and 69.4% in 183 lower ureteral stones. Transverse stone diameter, longitudinal stone diameter, ureteral diameter, and the ratio of ureter-to-stone diameter were significantly lower in patients with ureteral stone expulsion in upper ureteral stones and lower ureteral stones (P < .001 for all parameters). Logistic regression analysis revealed that only longitudinal stone diameter was a significant predictor of stone expulsion in patients with upper ureteral stones (odds ratio 0.580, P = .040) and lower ureteral stones (odds ratio 0.415, P = .012).

Longitudinal stone diameter was a significant predictor of stone expulsion in patients with upper ureteral stones and lower ureteral stones after medical expulsive therapy. Measurement of stone diameters in coronal reconstruction may help to better choose a patient who is suitable for medical expulsive therapy.