Fluoroscopy-free Moses Technology Holmium Laser for Treating Stones Associated with Infundibular Stenosis: a retrospective safety and efficacy cohort study

Abstract Background: Traditional flexible ureterorenoscopy (f-URS) with holmium laser for treatment of stones associated with intrarenal infundibular stenoses is performed with the aid of fluoroscopy. The use of C-arm and X-ray machines exposes both surgeons and patients to dangerous radiation. To eliminate radiation hazards, we applied X-ray free retrograde intrarenal surgery (RIRS) to treat stones associated with intrarenal infundibular stenoses. Purpose: To review our experience with retrograde intrarenal surgery (RIRS) for treatment of stones associated with intrarenal stenoses and present a treatment protocol on this basis. Patients and Methods: From March 2022 to August 2022, the records of 25 patients— 7 women (28 %) and 18men (72%) who had undergone f-URS by a single urologist at Chinese PLA General Hospital with and the same type of flexible ureteroscopes using Moses Technology holmium laser for calculi in infundibular stenosis were reviewed. The follow-up visit ranged from 4 to 6 weeks with plain radiography of the kidneys, ureters, and bladder and either renal ultrasonography or noncontrast CT. We statistically analyzed the differences in age, gender, BMI,operation time,postoperative hospital stay,stone size and site，number and size of associated calycesand other factors between the successful treatment group and the failed treatment group. Then multivariate logistic regression was used to further analyze the independent risk factor of sucessful rate of stones associated with intrarenal stenoses. Results: It was able to successfully identify stenoses and perform lithotripsy for 23 (92.0%) patients, and percutaneous nephrolithotomywas used for 2 failed patients. The surgery time was 45-180 minutes, with an average of 93.2 minutes. The postoperative hospital stay was 2-9 days, with an average of 3.4 days. According to the definition set by this study, the success rate was 72.0%(18/25 patients) of which 11(44.0%) patients were stone free (SF) and 7 (28.0%) patients had clinically insignificant residual fragments (CIRFs). The success rate of lower calyx calculus treatment was 40.0%, the success rate of upper and middle calyx calculus treatment was 93.3%; there was a statistical difference between the two groups (P=0.004). The success rate of ventral calculus treatment was 69.2%, and the success rate of dorsal calculus treatment was 75.0%; there was no significant statistical difference between these two success rates (P=0.748). The success rate was 86.7% when a single calyx was involved in the infundibular stenosis, and the success rate was 50.0% when multiple calyces were involved; there was a statistical difference between these two success rates (P=0.045). The diameter of calyx dilation did not affect the success rate of the surgery (P=0.562). There were no severe complications such as ureteral avulsion and perforation during the surgery. All patients had their ureters removed on the second day after the surgery. Conclusion: Calyx neck incision and lithotripsy technique under flexible ureterorenoscopy with Moses tchnology Holmium Laser is a safe and effective procedure with fewer complications. With a similar success rate as the traditional X-ray-guided balloon dilation technique, it has higher patient satisfaction and better promotion value. RIRS works best for patients at the upper and middle poles of kidney, while it also be attempted in patients with stones located in the lower calyx. With the development of flexible ureteroscope technology and the advancement of corresponding medical devices, RIRS provides a safe and minimally invasive technique for patients with stones associated with infundibular stenoses. It features a good promotion value.