Objectives. The purpose of this study was to evaluate whether repair of the ureteropelvic junction (UPJ) obstruction reduces the incidence of stones in stone-forming patients with concurrent UPJ obstruction.

Methods. We performed a retrospective study evaluating 90 patients with UPJ obstruction who underwent endopyelotomy and simultaneous stone extraction (group A) and 80 patients without UPJ obstruction who underwent only stone extraction (group B). Group A consisted of 52 men and 38 women with an average age of 54.4 years (range 15 to 82), and group B of 46 men and 34 women with an average age of 53.5 years (range 8 to 94). Metabolic evaluation was available in 47 patients of group A and 42 patients of group B.

Results. We achieved a stone-free state in all patients of both groups. Stone recurrence was observed in 7 patients (8%) in group A and in 32 patients (40%) in group B. Nine of 47 patients (19%) in group A showed metabolic abnormalities. In group B we found 30 of 42 patients (71.4%) with metabolic abnormalities.

Conclusions. Our results suggest that correction of the anatomic obstruction facilitates the drainage of the previously entrapped urine, and thus decreases the incidence of recurrent urinary stone formation.