Reporting the Impact of Pelvicalyceal System (PCS) Anatomy on Clinical Outcomes in Retrograde Intrarenal Surgery (RIRS) Studies: Can We Do Better? – Methodological Review from the Section of EAU Endourology

To analyze available randomized clinical trials (RCTs) comparing retrograde intrarenal surgery (RIRS) with other modalities for urinary stone treatment to determine the extent of comparing the pelvicalyceal system (PCS) anatomy between patients. In December 2024, a search was conducted in databases and was limited to publications that describe comparisons of experimental and control groups in the context of RIRS for stones only in the kidney (PCS). Only RCTs comparing RIRS with other modalities without publication date restriction were included due to their highest level of evidence in the hierarchy of primary research. The parameters used in the selected studies were analyzed to compare the differences between the groups, focusing on PCS anatomy. The final analysis included 27 publications from 2421 articles. The presence and/or degree of hydronephrosis were analyzed in 8 studies. Direct morphometric measurements were compared in 4 studies and were focused on the lower pole only, namely the infundibulopelvic angle, infundibular length, and infundibular width. Features such as the position of the renal pelvis in relation to the kidney parenchyma (intrarenal, extrarenal), number and orientation of calyces, as well as the existing PCS classifications were not compared or used. This review shows gaps in the literature while assessing and reporting on PCS anatomy in studies with RIRS. Unless studies mention these anatomical factors without excluding certain groups of patients, it is difficult to compare outcomes between modalities and in between studies.