Bladder stones larger than 2 cm are commonly treated by endoscopic fragmentation through the urethra. During transurethral cystolithotripsy for large stones, the procedure may be prolonged because of poor visibility, stone dust, bladder overdistension, and repeated need for irrigation or evacuation.

This randomized controlled trial will compare standal Holmium:YAG laser cystolithotripsy using a 17 Fr cystoscope sheath with the same procedure plus an adjunctive 8 Fr suprapubic catheter used only for bladder drainage during the operation. The suprapubic catheter will not be used for stone fragmentation or stone extraction.

The main outcome will be total operative time. Secondary outcomes will include fragmentation and clearance time, laser activation time, total laser energy, irrigation volume, visibility-related interruptions, stone-free rate at 30 days, complications, catheter duration, postoperative pain, and hospital stay.

This is a prospective, randomized, controlled, parallel-group clinical trial conducted at the Department of Urology, Beni-Suef University Hospital, Faculty of Medicine, Beni-Suef University, Egypt. Adult patients with radiologically confirmed bladder stones greater than 2 cm who are scheduled for elective transurethral cystolithotripsy will be enrolled after written informed consent.

Participants will be randomized in a 1:1 ratio into two groups. The control group will undergo standardized transurethral Holmium:YAG laser cystolithotripsy using a 17 Fr cystoscope sheath with conventional irrigation and transurethral evacuation only. The experimental group will undergo the same procedure with adjunctive 8 Fr suprapubic catheter drainage inserted under ultrasound guidance and cystoscopic visualization. The suprapubic catheter will be connected to free drainage during lithotripsy to assist bladder decompression and irrigation outflow. It will not be used for stone fragmentation, stone extraction, tract dilation, sheath placement, or percutaneous cystolithotripsy.

All procedures will use the same standardized cystoscopic access, Holmium:YAG laser platform, irrigation system, and transurethral evacuation method. The primary outcome is total operative time, measured from cystoscope insertion into the urethra until endoscopic confirmation of complete stone clearance and completion of final urethral catheter placement. Postoperative follow-up will continue for 30 days, including assessment of stone-free status by imaging and recording of perioperative complications.

Inclusion Criteria:

• Age 18 years or older.
• Radiologically confirmed bladder stone with maximum diameter greater than 2 cm.
• Scheduled for elective transurethral cystolithotripsy.
• Sterile urine culture before surgery, or adequately treated urinary tract infection according to culture sensitivity.
• Fit for spinal or general anesthesia.
• Ability to provide written informed consent.

Exclusion Criteria:

• Urethral stricture preventing safe cystoscopic access.
• Active uncontrolled urinary tract infection or sepsis.
• Neurogenic bladder with severely impaired bladder emptying requiring chronic catheterization.
• History of bladder cancer or suspected bladder tumor requiring simultaneous transurethral resection of bladder tumor.
• Coagulopathy or uncorrected bleeding tendency.
• Patients requiring concomitant transurethral resection of the prostate, Holmium laser enucleation of the prostate, or other prostate surgery in the same session.
• Previous pelvic radiotherapy or major lower urinary tract reconstruction.
• Pregnancy.
• Refusal to participate.

Individual participant data will not be shared because the study contains individual-level clinical and operative data. Only aggregated, de-identified study results will be reported in publications or presentations. Any future sharing of de-identified participant-level data would require additional approval from the Research Ethics Committee, Faculty of Medicine, Beni-Suef University.

Surgeon blinding is not feasible because of the nature of the intervention. Postoperative outcome assessment, including 30-day imaging assessment of stone-free status and complication review, will be performed by an outcome assessor not involved in the surgical procedure whenever feasible. Data analysis will be performed using coded groups.