Extracorporeal shock-wave lithotripsy monotherapy of partial staghorn calculi - Prognostic factors and long-term clinical results

Objective. To define factors affecting the success and long-term outcome of extracorporeal shock-wave lithotripsy (ESWL) monotherapy of partial staghorn calculi. Material and methods. We retrospectively reviewed 92 patients with partial staghorn calculi who were treated with ESWL monotherapy. The outcome of the treatment was evaluated after 3 months. Long-term follow-up data (> 24 months) were available for 49 patients. These data were further analyzed to determine long-term outcome. Results. At 3 months, the overall stone-free rate was 59.8%. Multiple ESWL sessions were required in 85.8% of patients. Stone surface area > 500 mm(2) was the only factor that significantly decreased the stone-free rate. Post-ESWL complications occurred in 12 patients (13%), among whom renal obstruction was observed in 10.8%. Secondary procedures were needed in 17 cases (18.4%). After a mean follow-up period of 7.5 years, the stone-free rate was 59.2% (29/49) and one-third of patients developed recurrence. In the long term, clinically insignificant residual fragments (CIRFs) passed spontaneously in 23% of patients, remained stable in 38.5% and became bigger in 38.5%. Regrowth of CIRFs was related to a history of stone recurrence. No patients showed deterioration of kidney function on the treated side and an improvement in pre-ESWL hydronephrosis was observed in 73.3% of patients. Conclusions. ESWL is suitable for staghorn stones <= 500 mm(2). In the long term, CIRFs became bigger and required secondary intervention in one-third of patients. A history of stone recurrence is a significant predictor of regrowth of CIRFs. ESWL provides long-term preservation of function of the treated kidneys; however, one-third of patients develop recurrence.