[Prognostic factors of spontaneous expulsion in ureteral lithiasis]

Medical treatment, extracorporeal shock wave lithotripsy (ESWL) and ureteroscopy are therapeutic options for ureteral stones. EWSL and endoscopic treatment of ureteral stones have a high success rate. However it has surgical as well as anaesthetic risks. For many patients, a medicinal treatment without invasive procedures is an option. Watchful waiting does not always result in stone clearance and may be associated with recurrent renal colic. The study of the prognostic factors for expulsion and the medical therapy will help us to select candidates for medical expulsive treatment.

To evaluate the characteristics of the stones and the medication administered (alpha blockers, NSAIDs or a combination of both) as predictors of spontaneous passage of the stone.

A retrospective observational study of 260 patients with 278 ureteral stones was conducted. Primary endpoint was stone expulsion. Univariate and multivariate analysis were conducted testing the effect of stone location, size and composition, and medication (alpha-blockers, NSAIDs, or combination) on stone clearance.

34,2% of the stones studied were spontaneously eliminated. Stone location (pelvic ureter, OR=1.823, p=0.013), size (>5 mm, OR=3.37, p>0.02), and medication (combination of alpha blockers and NSAIDs, OR=8.70, >0.001) were predictors of spontaneous clearance. Multivariate analysis confirmed size (p=0.006) and medication (p>0.001) as independent predictive factors.The use of the combination of NSAIDs and alpha-blockers versus observation multiplied times 8.21 (95%CI 3.37-20.01) the possibilities of spontaneous expulsion.

Size of stone and medication were confirmed as independent factors for spontaneous expulsion of ureteral stones.