Purpose: We aimed to describe the natural history of stone fragments ? 7 mm that remained after retrograde intrarenal
surgery (RIRS) in long-term follow-up.
Materials and Methods: We retrospectively reviewed 142 medical records of patients who had residual fragments
(RFs) ? 7 mm after RIRS. Patients were divided into 2 groups according to the size of RFs as ? 4 mm (group 1)
and 5 – 7 mm (group 2). Patients’ demographic data, stone characteristics, perioperative data and complications
were recorded. Re-growth of RFs, spontaneous passage, renal colic, infection and re-operation rates were our main
Result: A total of 142 patients (86 in group 1 / 56 in group 2) were followed for mean 54.45 ± 14.24 and 56.22 ±
10.28 months. Mean size of RFs was 2.85 ± 1.22 mm in group 1 and 6.81 ? 2.21 mm in group 2. Mean number of
RFs were 1.1 ± 0.2 in group 1 and 2.4 ± 1.6 in group 2 (P = .035). Spontaneous passage rate of RFs were 30.23%
and 17.85% in group 1 and 2, respectively (P = .032). No difference was observed in the re-growth rate of RFs
between the two groups (P = .094). Although no difference was observed in re-growth of RFs between the groups,
patients in group 2 were more likely to experience stone-related events such as renal colic and re-intervention rate
(P = .034, P = .029; respectively).
Conclusion: Our results demonstrate that RFs > 4 mm take higher risk in terms of stone-related events and should
be followed up more closely.