Outcomes of long-term follow-up of patients with conservative management of asymptomatic renal calculi

OBJECTIVE To evaluate the long-term outcomes of patients undergoing observation of asymptomatic renal calculi. PATIENTS AND METHODS This is a retrospective review of 50 patients with 85 stones undergoing observation with annual imaging from January 2005 to December 2009. The incidences of spontaneous stone passage, stone progression and intervention were evaluated and assessed for statistical difference according to initial size and location of stone. Percutaneous nephrolithotomy, shock wave lithotripsy and ureteroscopy were performed when patients developed complications from the stones. RESULTS Patients were followed up for a mean of 46 months. Sixteen percent had bilateral stones and 38% had multiple stones. The average stone size was 5.7 mm and 31%, 26% and 43% of the stones were located in the upper, middle and lower pole respectively. Overall incidences of spontaneous passage, progression and intervention were 20%, 45.9% and 7.1% respectively. Stones measuring 5 mm or less were significantly more likely to pass (P = 0.006). There was no significant difference in the incidence of passage according to the initial location of the stone (P = 0.092). There was no significant difference in intervention or progression according to the initial size (P = 0.477 and 0.282 respectively) or location of stone (P = 0.068 and 0.787 respectively). CONCLUSIONS Patients with asymptomatic renal stones may be managed conservatively in view of low risk of intervention (7.1%). Annual imaging should be performed as half of these stones will progress in size.