This multicenter, prospective, randomized clinical trial compares FANS-assisted flexible ureteroscopy (FURS) with suction-assisted mini-percutaneous nephrolithotomy (mini-PCNL) for the treatment of renal stones measuring 2-3 cm. A total of 280 patients will be enrolled across nine tertiary centers and randomized 1:1 to either technique. The primary endpoint is stone-free rate (SFR) at 1 month, assessed by non-contrast CT. Secondary outcomes include operative time, intraoperative complications, postoperative morbidity (Clavien-Dindo), pain scores, hospital stay, reinterventions, and quality of life (EQ-5D-5L). The study aims to provide the first high-quality head-to-head evidence comparing these two modern suction-enhanced technologies, with the goal of defining the optimal minimally invasive approach for medium-sized renal stones.

Aim of the Study

The primary aim of this study is to compare the stone-free rate (SFR) of FANS-assisted flexible ureteroscopy versus suction-assisted mini-percutaneous nephrolithotomy (mini-PCNL) in patients with renal stones measuring 2 to 3 cm. Secondary aims include comparing perioperative outcomes, complication rates, length of hospital stay, and patient-reported quality of life between the two treatment modalities.

Patients and Methods Study Design

This is a prospective, multicenter, randomized, superiority trial. Patients will be recruited from nine high-volume tertiary referral centers. Participants will be randomized in a 1:1ratio to undergo either FANS-based flexible ureteroscopy or suction mini-PCNL using a computer-generated randomization tables, stratified by each center. Allocation concealment will be maintained using sequentially numbered, opaque, sealed envelopes (SNOSE) prepared by an independent person who is not involved in patients' recruitment or treatment. Surgeons and investigators will be blinded to group allocation until the point of intervention.

Ethical Considerations The study protocol will be approved by the Institutional Review Board (IRB) of each participating center. All patients will provide written informed consent before enrollment. The study will be conducted in accordance with the principles of the Declaration of Helsinki.

Patient Evaluation and Recruitment All patients will undergo a standardized preoperative assessment including medical history, physical examination, blood tests (CBC, renal function, coagulation profile), urinalysis, urine culture, and non-contrast CT (NCCT) for stone size, density (HU), and volume assessment. Eligible patients will be screened and enrolled after providing informed consent. Antibiotic prophylaxis will be administered according to European Association of Urology (EAU) guidelines.

Inclusion Criteria:

• Adults ≥18 years old.
• Single or multiple renal stones measuring 2 -3 cm (diagnosed by NCCT).
• Negative urine culture prior to surgery.
• Suitable for general/spinal anesthesia.
• Signed informed consent.

Exclusion Criteria:

• Active urinary tract infection.
• Anomalous renal anatomy (e.g., horseshoe kidney).
• Severe ureteral strictures preventing retrograde access.
• Coagulopathy or inability to discontinue anticoagulation.

Participants and surgeons are unblinded due to the nature of surgical interventions. However, postoperative imaging and clinical outcome assessment will be performed by blinded independent assessors."