This study will evaluate the safety and effectiveness of thulium laser enucleation of the prostate combined with bladder neck incision in men with small-volume benign prostatic hyperplasia (BPH). Small-volume BPH may still cause significant bladder outlet obstruction and bothersome lower urinary tract symptoms, and the optimal surgical treatment for these patients remains uncertain.

In this multicenter, randomized, single-blind, controlled trial, 426 eligible men aged 40 to 80 years will be assigned in a 1:1:1 ratio to one of three groups: thulium laser enucleation of the prostate combined with bladder neck incision, thulium laser enucleation alone, or transurethral resection of the prostate. The main goal is to compare the incidence of bladder neck contracture at 6 months after surgery. Other outcomes include symptom improvement, urinary flow, pain score, sexual function, and safety outcomes during follow-up.

Benign prostatic hyperplasia (BPH) is a common condition in aging men and may lead to bladder outlet obstruction and lower urinary tract symptoms. In some patients, clinically significant obstruction and symptoms can occur even when prostate volume is relatively small. Surgical treatment of small-volume BPH remains challenging because these patients may have an increased risk of postoperative bladder neck contracture, and high-quality evidence for the optimal surgical approach is limited.

This study is a multicenter, randomized, single-blind, parallel-controlled clinical trial designed to evaluate the safety and efficacy of thulium laser enucleation of the prostate combined with bladder neck incision in patients with small-volume BPH. A total of 426 male participants aged 40 to 80 years who meet the eligibility criteria will be enrolled and randomly assigned in a 1:1:1 ratio to one of three treatment groups: (1) thulium laser enucleation of the prostate combined with bladder neck incision, (2) thulium laser enucleation of the prostate alone, or (3) transurethral resection of the prostate.

Small-volume BPH in this study is defined as clinically diagnosed BPH with moderate-to-severe lower urinary tract symptoms or impaired voiding function and a prostate volume of less than 30 mL measured by transrectal ultrasound. The primary endpoint is the incidence of bladder neck contracture at 6 months after surgery. Secondary outcomes include safety outcomes and changes from baseline in International Prostate Symptom Score (IPSS), maximum urinary flow rate (Qmax), Visual Analogue Scale (VAS) score, and IPSS response rate at 3 and 6 months after surgery. Exploratory outcomes include changes in post-void residual urine volume and sexual function assessed by the International Index of Erectile Function-5 (IIEF-5) and the Male Sexual Health Questionnaire for Ejaculatory Dysfunction (MSHQ-EjD).

Participants will undergo screening, surgical treatment, and postoperative follow-up. Follow-up visits will be conducted at 30 ± 3 days, 90 ± 3 days, and 180 ± 7 days after surgery. Outcome assessments will include symptom scores, uroflowmetry, post-void residual urine volume, adverse events, and cystoscopy at the 180-day visit to assess bladder neck contracture. The results of this trial are expected to provide evidence for an optimized surgical strategy for patients with small-volume BPH.

Inclusion Criteria:

• Male patients aged 40-80 years.
• Diagnosis of benign prostatic hyperplasia (BPH) and scheduled to undergo surgical treatment.
• International Prostate Symptom Score (IPSS) of at least 12, maximum urinary flow rate of no more than 15 mL/s, with a voided volume greater than 150 mL.
• Prostate volume of less than 30 mL measured by transrectal ultrasound (TRUS), calculated as length × width × height × 0.52.
• Ability, as assessed by the investigator, to understand the study requirements and complete the scheduled treatment, follow-up visits, and study-related assessments.

Exclusion Criteria:

• Inability or refusal to provide written informed consent, or inability to comply with the required follow-up schedule.
• Prostate-specific antigen (PSA) level of 10 ng/mL or higher, unless prostate cancer has been excluded by biopsy.
• Confirmed or suspected prostate or bladder malignancy.
• Pre-existing bladder neck contracture or urethral stricture before surgery.
• Known coagulation disorder or abnormal coagulation function.
• Neurogenic bladder or detrusor underactivity that may affect bladder or urethral sphincter function.
• Benign prostatic hyperplasia (BPH) complicated by acute urinary tract infection, acute prostatitis, or bacterial prostatitis.
• History of prostate surgery, urethral stricture, or neurogenic bladder.
• History of prostate cancer or pelvic radiotherapy.
• Severe cardiovascular disease, pulmonary disease, or other systemic disease that, in the investigator's judgment, would make the patient unable to tolerate surgery.
• Participation in another clinical trial related to benign prostatic hyperplasia (BPH) within 3 months before enrolment.
• Any other condition that, in the investigator's opinion, makes the patient unsuitable for participation in this study.

No plan to share individual participant data at this time.

Due to the nature of the surgical interventions, surgeons and care providers cannot be blinded. Participants will not be actively informed of treatment assignment whenever feasible, and postoperative outcome assessors will remain blinded whenever possible.