Objective Removing remained or forgotten ureteral stents is challenging. We present our experience with heavily encrusted ureteral stents and discuss the endourologic treatment options as well as their effectivity. Methods 17 patients were collected and treated at our clinic. Medical records of the patients were retrospectively reviewed and analyzed. Results Seventeen patients (mean 51.82±17.98 years of age) with forgotten stents (mean 16.06±13.54 months of indwelling). According to the Forgotten-Encrusted-Calcified (FECal) classification, all patients were above grade Ⅲ (100%), including grade Ⅴ(7/17,41.2%),grade Ⅳ(7/17,41.2%),grade Ⅲ(3/17,17.6%). All patients were undergoing the operation and removed the stent successfully. In this study, 5 patients（5/17,29.4%）were analyzed for the composition of the stone. Four patients were phosphate calcium and the other one was oxalate calcium. Analysis of the causes of double J tube retention was mainly due to lack of understanding of the disease and forgetting caused by busy work. Meanwhile, 58.8% of the patients hoped to be supervised and reminded by the hospital to avoid the occurrence of stent retention. Conclusion Endoscopic treatment of ureteral stent retention is safe, minimally invasive and effective. The whole process of health management is one of the helpful way to prevent stent retention after urological surgery.

Objective To evaluate the therapeutic effectiveness and safety of flexible ureteroscopes without preoperative ureteral stent placement based on the real world study. Methods A total of 351 patients who underwent flexible ureteroscopy (FURS) lithotripsy in The Urology Department of Chengdu Fifth People's Hospital from January 2018 to November 2021 were collected. Based on the real world study, 293 patients without preoperative indwelling of ureteral stents were divided into non-stented group, and the remaining 58 patients with preoperative indwelling of ureteral stents were divided into pre-stented group under the premise of fully informing patients whether to choose preoperative indwelling of ureteral stents.. The operative time, length of hospital stay, stone-free rates (SFRs) (3 days post-operation and 30 days post-operation), complications, and hospital costs of the two groups were respectively compared. Results The average operative time of Pre-stented group was longer than that of Non-stented group (P=0.1680), the SFRs of Pre-stented group were significantly higher than those of Non-stented group at 3 days postoperatively（P=0.0323). However, no significant difference was found in the SFRs between two group 30 days postoperatively（P>0.05), and no difference in complications rates between two groups. The average length of hospital stays and the average hospital costs were substantially lower in Non-stented group than those in Pre-stented group（P<0.05). Conclusions These results indicated that preoperative ureteral stent placement is not necessary in FURS , and without pre-stented ureteral stent is effective and safe for the treatment of upper urinary calculi through FURS.