Effects of renal parenchymal volume and total renal volume on success in retrograde intrarenal surgery

Abstract

Objective: Renal parenchymal volume known as an indicator of the number of nephrons in the kidney. We predict that the increase in renal parenchyma volume will increase diuresis and facilitate the excretion of fragments after RIRS procedure. Therefore, increased renal parenchymal volume might be suggested as a factor affecting the success of RIRS procedure.Material and Methods: Out of 238 patients who underwent RIRS in our clinic, 104 patients who underwent primary RIRS due to single kidney stone and who underwent contrast-enhanced computed tomoghraphy were included in the study. The demographic, clinical and radiological (renal parenchymal volume and total renal volume) datas of all patients included were evaluated. Patients were divided into 2 groups according to the success status after RIRS, as successful and unsuccessful groups.Results: There was no significant difference in total renal volume between the two groups (213.3±54.9 cm3 in the successful group, 204.4±65.7 cm3 in the unsuccessful group, p=0.521). While the mean renal parenchymal volume in the successful group was 168.3±46.1 cm3 , it was 125.5±29.9 cm3 in the unsuccessful group, and the difference was statistically significant (p<0.001). In the ROC analysis, the cut-off value for renal parenchymal volume predicting the presence of residual stones after RIRS was found to be ≤141.3 cm3. According to multivariate logistic regression analysis, elevated stone burden (OR=1.02; 95% Cl=1.009-1.03; p<0.001), localized stones in the lower pole (OR=31.673; 95% Cl=3.315-302.623; p=0.003 ) and RPV≤141.3 cm3 (OR=5.923; 95% Cl=2.886-19.263; p=0.008) were found to be independent risk factors for success of RIRS procedure.Conclusion: Renal parenchymal volume is a practical and cost-effective parameter that can be used to predict success rates in patients undergoing RIRS for kidney stones.