Fluoroscopy-free Moses technology for treating nephrolithiasis accompanied with infundibular stenosis: a prospective safety and efficacy cohort study.

Background: Utilization of C-arm and X-ray machines in flexible ureterorenoscopy (f-URS) with Holmium Laser for the treatment of stones exposes both surgeons and patients to potentially harmful radiation. This study investigates the safety and efficacy of our new procedure, X-ray-free retrograde intrarenal surgery (RIRS), for treating nephrolithiasis associated with intrarenal infundibular stenosis.

Methods: From Apr 2023 to Mar 2024, a prospective analysis as conducted on the medical records of 25 patients, comprising 7 women (28%) and 18 men (72%). Postoperative follow-up at 3 and 6 months revealed stone-free rates of 76% and 84%, respectively.Univariate logistic regression was applied to further analyze the independent risk factor of the successful rate of stones accompanied with intrarenal stenoses.

Results: According to the definition established in this study identifying and incising the narrow calyx neck and removing the stone completely without fluoroscopic guidance, the success rate reached 72.0% (18/25). There was a statistical difference in success rates between the lower calyx calculus treatment group (4) and the upper/middle calyx calculus treatment group (14) (P = 0.004). There was no significant statistical difference in success rates between anterior stenosis with calculus treatment (9) and posterior stenosis with calculus treatment (9) (P = 0.748). The location of calculus have a significant impact on the surgical success rate (P = 0.013).

Conclusions: Flexible ureterorenoscopy (f-URS) using calyx neck incision and Moses mode holmium laser lithotripsy appears to be a safe and effective technique. With a success rate comparable to that of the traditional X-ray-guided balloon dilation technique, RIRS is particularly suitable for patients with kidney stones located at the upper and middle poles of the kidney, while it can also be considered for patients with stones in the lower calyx. Application to lower calyx stones should be cautiously considered due to anatomical challenges and relatively lower success rates observed.

Trial registration: The trial was registered prior to patient enrollment at the Chinese Clinical Trial Registry (ChiCTR2300070059), date of registration: March 31st, 2023.