The concept of ‘stone free’ remains an enigma. To some urologists this refers to complete removal of all visible fragments, to others its removal of all ‘clinically significant’ fragments (generally regarded as fragments >2mm), and to some it is absence of fragments on CT. It is a common scenario during endoscopic surgery to consider small residual fragments (SRF) <1mm too small for retrieval and thus left in situ with the hypothesis that they will pass without causing patient distress. This group in Germany present the fate of 85 consecutive patients rendered ‘stone free’ after retrograde intrarenal surgery (RIRS) – complete stone clearance or SRF <1mm as determined endoscopically at the end of the procedure. Stone-related events (SRE) occurred ipsilaterally in 24.7% within five years from original RIRS. Unsurprisingly, ‘high risk stone formers’ and ‘obesity’ were identified as risk factors for SRE. In patients with a low risk profile, SRF were highly predictive for SRE on the ipsilateral side. Despite several limitations to this study (i.e. small numbers, subjective assessment of residual fragment size, loss to follow-up, subjective patient reported outcomes, and no imaging performed on asymptomatic patients) residual fragments may well be significant to the future course of patients, therefore strengthening the argument that patients with residual fragments of any size should not be labelled as ‘stone free’. 

Endoscopically determined stone clearance predicts disease recurrence within 5 years after retrograde intrarenal surgery.
Hein S, Miernik A, Wilhelm K, et al.
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Hamid Abboudi

Imperial College Healthcare NHS Trust.

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