A0779 - Outcomes from practice of Retrograde Intrarenal Surgery (RIRS) in a paediatric setting of various age groups: A global study across 8 centres

Introduction & Objectives: To analyse and report the practice, outcomes and lessons learnt from a global series of retrograde intrarenal surgery (RIRS) in a paediatric multicentre series.Materials & Methods: Retrospective review of anonymized pooled data gathered globally from 8 centres in paediatric patients (≤18 years of age) who had renal stones and underwent RIRS from 2015 to 2020 was performed. Patient demographics, perioperative parameters, stone characteristics, complications and stone-free rate (SFR) were analysed. Residual fragments (RFs) were defined as a single fragment >2mm or multiple fragments. Our cohort was stratified by age into 3 groups: ≤5 years (Group A), 5-10 years (Group B) and ≥10 years (Group C). T-test and Mann–Whitney were used for continuous variables. Categorical data between groups were analysed using the χ2 test.Results: A total of 314 patients had complete data for analysis. The age of the cohort was 9.54 +/- 4.76 years (range 5 months to 16 years). The number of patients in groups A, B and C were 67 (21.3%), 83 (26.4%) and 164 (52.2%) respectively. Mean stone size of the cohort was 10.7 +/- 4.62 mm (range: 1-30 mm). Stone size was not significantly different between the 3 age groups (9.94 +/- 4.09, 10.6 +/- 3.79 and 11.1 +/- 5.15 mm in groups A, B and C respectively). Pre-stenting was performed in 155 (49.4%) of patients, ureteral access sheaths (UAS) was used in 54.5% of patients with majority (71%) utilizing holmium laser for stone fragmentation. There were 43 cases (13.7%) of post-operative complications, all classified as modified Clavein Dindo (CD) 1 and 2; Two cases of sepsis was managed conservatively with antibiotics (Group C, CD2). Stone size ≥10mm was associated with higher rates of intraoperative haematuria compared to stone size <10mm (5.7% versus 0.7%, p=0.036); comparisons of other post-surgical complications did not yield any significant differences. Univariate analysis showed that patients who were symptomatic (OR 0.34 95% CI 0.18-0.65, p<0.001) and presence of multiple stones (OR 3.57 95% CI 2.10-6.17, p<0.001) were predictors of residual fragments. Multivariate generalized linear model incorporating pre-operative and intraoperative characteristics did not find any significant associations with SFR.Conclusions: RIRS is acceptable as a firstline intervention in the paediatric population with reasonable efficacy and low morbidity; Complications are slightly higher in Group A and this should be taken into account while counselling patients.