Prediction of Surgical Intervention for Distal Ureteral Stones

Eighty percent of patients with distal ureteral stones <10 mm will ultimately pass the stone under conservative care. Nonetheless, some may experience related morbidity before surgical intervention is performed. Our study aims to find predictive variables for surgical intervention. We retrospectively surveyed medical records of patients found to have distal ureteral stone up to 10 mm by noncontrast computed tomography (NCCT) done between March 1, 2016 and May 31, 2017. Demographic, clinical, laboratory, and radiologic data were obtained. We compared characteristics of patients who underwent surgical intervention (ureteroscopy/renal drainage) with those treated conservatively. A total of 268 consecutive patients were included: 226 (84%) were male and the average age was 46 years (18-82). Of these patients, 60 patients (22%) underwent surgical intervention (group 1) and 208 patients (78%) were treated expectantly (group 2). No significant differences were observed with respect to demographic data or proportion of patients treated with medical expulsive therapy between the groups. Univariate analysis found stone diameter, stone-to-ureterovesical junction (UVJ) distance, stone density, presence of a "rim sign" on NCCT, and pain duration at presentation to be significantly different between the groups. Multivariate analysis showed stone diameter, stone-to-UVJ distance, and pain duration at presentation to be independently predictive for intervention. Receiver operating characteristics curve analysis identified stone size >4 mm, stone-to-UVJ distance >4 mm, and pain duration >4 days to be the most significant cutoff points for patient risk stratification-"Rule of 4's." Further analysis showed that the prevalence of intervention among patients with 0, 1, 2, and 3 risk factors was 4.3%, 22.1%, 45%, and 66.7%, respectively. Stone size, stone distance from the UVJ, and pain duration play a significant role in predicting surgical intervention. "Rule of 4's" may aid in early recognition of patients who will ultimately undergo intervention and omit the burden of nonfavorable expectant management.