Classification of the renal papillary abnormalities by flexible ureteroscopy: evaluation of the 2016 version and update

INTRODUCTION: To assess the use of the 2016 proposed classification of the renal papillary abnormalities during flexible ureteroscopy that aims to standardize their description. PATIENTS AND METHODS: We performed a prospective monocentric single operator collection of the data using this classification during 88 consecutive flexible ureteroscopies required for renal stones treatment. Outcome measurements and statistical analysis: data of stones analysis (microscopy and infrared spectrophotometry) and of serum and urines biochemical samples have been compared with the results of the classified endoscopic descriptions. RESULTS: Mean duration of description was 81.4 s. We reported that 83% of the patients had Randall plaques (RP), as only 4.5% of the patients had no abnormality. Concerning the papillary stones and anchored stones were observed in 30.7% and aspect of intraductal crystallization (Sc) in 15.9%. Erosions were present in 55.7% and extrophic papillae in 8%. Sa1 and Pa2 were significantly correlated to RP, anchored stones (Sa) to papillary erosions and calcium phosphate stones to intraductal crystallization. Hypercalciuria was significantly higher in Sa2 than Sa1 stones. CONCLUSIONS: The different descriptions in the 2016 classification were confirmed by the results of this study. Papillary abnormalities are consequences of stones development. Their descriptions could also improve the follow-up and the diagnosis of a metabolic lithogenesis. We recommend their systematic description during ureteroscopy. Some improvements are proposed to update this classification.