Outcome Analysis of Asymptomatic Lower Pole Stones in Children

Purpose Lower pole renal stones in children usually present incidentally. To our knowledge frequency and need for intervention are unknown. We evaluated the outcomes of asymptomatic, incidentally found lower pole renal stones in children. Materials and Methods We retrospectively reviewed the charts and renal ultrasounds of children with lower pole stones seen during a period of 14 years. The unpaired t-test was used to determine factors that might predict the need for stone intervention, including size, growth rate, type of stone and underlying metabolic disease. The success rate of nonoperative management, defined by spontaneous passage or lack of growth in the absence of symptoms, was calculated. Results A total of 224 children were found to have lower pole stones. Mean ± SD age at presentation was 95.2 ± 65.3 months. Of the patients 120 (53.6%) spontaneously passed stones. Of the stones 25% remained asymptomatic and did not grow with time. Intervention was performed in 48 children (21.4%). Stones originally managed conservatively that later required intervention were significantly larger at baseline than stones that did not require intervention through the end of followup (median 7 vs 5 mm, p <0.001) and those that grew with time (median stone size 8 mm at surgical intervention, p = 0.01). Conclusions Our data suggest that asymptomatic lower pole renal stones can be followed conservatively. Of the calculi 78.6% passed spontaneously or remained asymptomatic and did not grow. Median initial size greater than 7 mm and stone growth with time were significant risk factors that predicted the need for intervention.