Ureteral stent encrustation: evaluation of available scores as predictors of a complex surgery

BACKGROUND: Stent encrustation is an uncommon event (13%) with a significant impact in patients' management. Aim of our study was to evaluate the available grading systems for encrusted stents. METHODS: A retrospective analysis of encrusted stents was performed in four Italian centers between 2006 and 2020. Encrusted stents were classified according to four classifications: the Forgotten Encrusted Calcificated (FECal) Score, the Kidney Ureter Bladder (KUB) Score, the Visual Grading for Ureteral Encrusted Stent Classification and the Encrusta-tion Burden Score (EBS). Classifications were evaluated to predict complex surgery defined as: long operative time (>60 min), need of more than one surgery, and need of a percutaneous approach. The scores were compared with receiver operating characteristic (ROC) analysis as predictors of complex surgery. RESULTS: Seventy-seven patients were evaluated with a median age of 62 years (65/70). Overall FECal score >2 was present in 45/77 (58%) patients, median KUB score was 9 (6/14) and severe EBS was found in 47/77 (63%) patients. Patients were managed with cyst lithotripsy in 13/77 (17%), with ureteroscopy in 58/77 (75%) and with percutaneous nephrolithotomy (PCNL) in 6/77 (8%). Overall, 6/77 (8%) patients required a second intervention to remove the en-crusted stent. All classifications predicted the need of complex surgery. On ROC analysis KUB score presented a better accuracy in predicting complex surgery compared to FECal, V-GUES and encrusted burden. CONCLUSIONS: KUB score, FECal score, V-GUES score, and encrustation burden accurately predict the need of a complex surgery. KUB showed to be superior to other classifications according to our results.