Osman MM et al. (2005) 5-year-follow-up of patients with clinically insignificant residual fragments after extracorporeal shockwave lithotripsy. Eur Urol 47: 860–864

The term 'clinically insignificant residual fragment' (CIRF) was coined to describe the small (≤4 mm) calculi that remain in the kidney or ureter following extracorporeal shockwave lithotripsy (ESWL). These fragments are expected to pass spontaneously. However, several studies have shown that so-called CIRFs can persist and grow to become a significant problem that requires further treatment. The term CIRF, and the management of these fragments, are controversial.

Osman and colleagues in Germany have analyzed questionnaires completed by 173 patients who underwent ESWL for urolithiasis 5 years previously. All patients were discharged with CIRFs.

The questionnaires showed that the CIRFs had passed spontaneously in 78.6% of the patients. These patients had experienced no recurrence during the 5-year follow-up period. However, regrowth of persisting CIRFs had occurred in 21.4% of patients. All these patients had required further treatment.

No correlation was found between measures taken to optimise fragment clearance (including increased fluid intake, weight reduction and medication) and stone regrowth. The authors attributed this to “the special patient-care characteristics in the German health system”, explaining that inconsistent treatment modalities made the quality of these measures difficult to assess.

The authors concluded that, with one-fifth of patients discharged with CIRFs requiring further treatment for stone regrowth, close follow-up is required following ESWL.