Systematic radiologic detection of kidney stones in Canadian children: a new era of asymptomatic stones?

Summary Introduction Asymptomatic, or incidental, pediatric kidney stones detected on abdominal imaging pose a clinical challenge as their significance and expected outcome are not well described. Our primary objective was to estimate the incidence of nephrolithiasis in pediatric patients undergoing abdominal ultrasound (US) or computerized tomography (CT), for all indications , in a pediatric tertiary care hospital. Our secondary objective was to determine the clinical outcome of these radiographically detected stones . Methods All abdominal US or CT radiology reports for patients under 18 years of age CT between January 1, 2011 and December 31, 2016 were retrieved. Reports were automatically flagged using textual analysis if they contained one of 32 keywords potentially indicating nephrolithiasis. Flagged reports, as well as 10% of unflagged reports, were reviewed to confirm the radiologists impression of presence or absence of stones. Patient and stone related clinical data were extracted. Results 2449 (5%) of 53 235 imaging reports cited at least one of the keywords. Manual review of flagged reports identified 498 studies having a radiologist impression of stones (244 unique patients). Stone incidence in children undergoing abdominal imaging more than doubled between 2011 and 2016. Medical record review found that 140 patients (57%) were symptomatic while the other 104 patients (43%) were asymptomatic. Spontaneous resolution was greater (57% versus 34%) in asymptomatic patients compared to symptomatic patients. Asymptomatic patients were younger with a median age of 0.6 compared to 12.3 years. Asymptomatic and symptomatic stones were followed for similar lengths of time (2.3 vs 2.0 years, p >0.05) and had a similar number of follow-up ultrasounds (3.9 vs 4.6 studies, p >0.05). Conclusions The incidence of radiologically identified stones in children undergoing abdominal imaging at our center increased over time. Asymptomatic stones follow a benign course with minimal need for intervention, however were detected almost as frequently as symptomatic stones. Asymptomatic stones may represent an increase healthcare resource utilization due to similar follow up compared to symptomatic stones. Further research regarding the optimal imaging intervals and long-term follow-up for asymptomatic stones is warranted.