Abstract:Objective To analyze the effect of indwelling double J stent before stage II operation on ureteral injury and pain in patients with upper urinary calculi treated by flexible ureteroscopic lithotripsy (FURL).Methods A total of 348 patients with upper urinary calculi from January 2020 to November 2023 were selected. According to the different time of indwelling double J stent, the patients were divided into the 2 weeks group (n = 85), the 3 weeks group (n = 98), the 4 weeks group (n = 92), and non-indwelling double J stent (n = 73). The 2 weeks group, 3 weeks group and 4 weeks group had double J stent indwelled at 2, 3 and 4 weeks before the operation, respectively. The non-indwelling double J stent group did not have a double J stent indwelled. All four groups received FURL treatment and were observed until one month after the operation. The surgical conditions, hospitalization conditions, stone clearance effects, ureteral wall injury conditions, pain conditions and the occurrence of complications were compared in the four groups.Results The operation time of the non-indwelling double J stent group was longer than that of the 2 weeks group, 3 weeks group and 4 weeks group, and the difference was statistically significant (P < 0.05). The success rates of intraocular sheath insertion, flexible endoscope insertion and stone clearance 2 weeks after surgery in the non-indwelling double J stent group were significantly lower than those in the 2 weeks group, 3 weeks group and 4 weeks group, and the differences were statistically significant (P < 0.05). Compared with the 4 weeks group, the proportion of post-ureteroscopic lesion scale (PULS) grade 1 was higher in the 2 weeks group, 3 weeks group and the non-indwelling double J stent group, while the proportion of grade 3 was lower. The differences were statistically significant (P < 0.05); Compared with the non-indwelling double J stent group and the 4 weeks group, the proportions of irritation sign of bladder, urinary tract infection and gross hematuria in the 2 weeks group and the 3 weeks group were significantly lower, and the differences were statistically significant (P < 0.05).Conclusion The indwelling of a double J stent before stage II surgery can shorten the operation time of FURL for the treatment of upper urinary calculi, increase the success rate of endoscope sheath placement, flexible endoscope placement and stone clearance rate. Compared with 4 weeks before the operation, indwelling double J stent at 2 weeks and 3 weeks before the operation can reduce the risk of ureteral wall injury and has higher safety.