↵* One patient who had intractable pain needed intervention.

↵† One patient was treated because of new colic with obstruction; 2 patients were treated to relieve stone complicating pyelonephritis.

↵‡ One patient in each category had recurrent pain 2 days later.

↵§ One of 2 HIV-positive patients on indinavir sulfate, who had nonradioopaque stones, and 2 other patients with 2- and 3-mm stones at ureteropelvic junction were relieved after vigorous hydration; 1 patient left against medical advice.

↵‖ Condition of 2 patients was incorrectly interpreted by on-call nuclear physician as complete obstruction, and 1 patient had intractable severe pain.

Positive predictive value of helical CT for obstruction was 56% (based on results of scintigraphy).