Background:Percutaneous nephrolithotomy (PCNL) is the most widely recommended treatment for calyceal diverticular calculi,providing excellent stone-free results.However,its invasiveness is not negligible considering its major complication rates.Flexible ureteroscopy (FURS) is currently used to treat calyceal diverticula.However,the greatest drawback of FURS is locating the diverticulum since its neck is narrow and concealed.In such a case,the FURS procedure must be converted to PCNL.The aim of this study was to evaluate ltrasound-guided flexible ureteroscopy (UFURS) identifying diverticulum and the management of calyceal diverticular calculi.Methods:A retrospective analysis was conducted on 24 patients who had calyceal diverticular calculi.In all 12 patients in the UFURS group,direct FURS failed to find evidence of calyceal diverticula but were confirmed with imaging.The other 12 patients in the PCNL group received PCNL plus fulguration of the diverticular walls.Results:Puncture ofcalyceal diverticulum was successful in all 12 UFURS patients.Two patients in this group had postoperative residual calculi and two patients developed fever.In the PCNL group,percutaneous renal access and lithotomy were successful in all 12 patients.One patient in this group had residual calculi,one had perirenal hematoma,and two patients developed fever.No significant difference was found in the operating time (UFURS vs.PCNL,91.8 ± 24.2 vs.86.3 ± 18.7 min),stone-free rate (UFURS vs.PCNL,9/12 vs.10/12),and rate of successful lithotripsy (UFURS vs.PCNL,10/12 vs.11/12) between the two groups (all P ＞ 0.05).Postoperative pain scores in the FURS group were significantly lower than that in the PCNL group (2.7 ± 1.2 vs.6.2 ± 1.5,P ＜ 0.05).Hospital stay in the UFURS group was significantly shorter than that in the PCNL group (3.4 ± 0.8 vs.5.4 ± 1.0 days,P ＜ 0.05).All patients were symptom-free following surgery (UFURS vs.PCNL,10/10 vs.12/12).Conclusion:Ultrasound-guided puncture facilitates identification of calyceal diverticula during FURS and improves the success rate of FURS surgery.