Prospective long-term followup of patients with asymptomatic lower pole caliceal stones.

Purpose: The intervention time of asymptomatic lower pole calculi remains controversial. In this prospective study we evaluated the natural history and progression rate of asymptomatic lower pole stones.Materials and Methods: Patients were followed every 6 months. Computerized tomography in even years, ultrasound scan in odd years after initial visit and abdominal plain films between these visits were evaluated. The largest diameter was measured for each calculus and the cumulative diameter was calculated for cases of multiple stones. Disease progression was defined as pain experienced during followup, stone growth or the need for intervention.Results: A total of 24 patients, 14 male and 10 female, were followed for a mean of 52.3 months (range 24 to 72). Of the 24 patients 3 had bilateral lower pole stones. Mean cumulative stone diameter at presentation was 8.8 mm (range 2.0 to 26.0). Progression in stone size was demonstrated in 9 of 27 renal units (33.3%) with 2 (11.1%) requiring intervention. There wa...