Microscopic Varicocele Bypass Versus Ligation

This prospective, single-blind, randomized controlled trial is conducted at the Urology and Andrology Center of Sichuan Provincial People's Hospital, led by Principal Investigator Dou Ke, to evaluate the safety and efficacy of microscopic varicocele transposition surgery compared with microscopic simple ligation for treating left varicocele. The study spans from May 2025 to December 2027.

1. Study Design Details

   Randomization Process:

   Utilizing a computer-generated random number table with a 1:1 allocation ratio, patients are assigned to either group. To ensure randomness, the randomization sequence is generated by an independent statistician not involved in patient enrollment or intervention delivery. Block randomization with block sizes of 4-8 will be employed to balance group sizes over time.

   Blinding Implementation:

   In this single-blind design, patients remain unaware of their group assignment throughout the study. To maintain blinding, patient identification codes are used instead of names during follow-up, and outcome assessors are trained to conduct evaluations without accessing group allocation information. Surgeons and researchers directly involved in the surgical procedures are aware of the group assignment for proper procedure execution.

   Surgical Techniques:

   Experimental Group: Under 8-15× microscopic magnification, the surgical team will perform end-to-side or end-to-end anastomosis of the spermatic vein with other vessels, typically the inferior epigastric vein. The surgical procedure includes meticulous dissection to isolate the spermatic vein while carefully preserving the testicular artery, lymphatic vessels, and nerve fibers. Specialized microsurgical instruments, such as microscissors with a tip diameter of 0.1-0.3 mm and 10-11-0 nylon sutures, are used for precise anastomosis.

   Control Group: Microscopic simple ligation involves double ligation and division of the spermatic veins. The surgical field exposure, including the incision size (usually 3-4 cm), and the method of protecting testicular vasculature and other structures, are kept identical to the experimental group to minimize confounding factors.

2. Measurement and Assessment Details

   Ultrasound Evaluation:

   Color Doppler ultrasound will be performed using high-resolution machines (e.g., with a probe frequency of 7-12 MHz) by experienced sonographers blinded to group assignment. For the experimental group, when assessing anastomotic vessel patency, the angle of insonation will be maintained at ≤60° to accurately measure blood flow velocity. Standardized scanning protocols will be followed, including specific patient positions (supine and standing) to detect varicocele reflux.

   Semen Analysis:

   Semen samples will be collected via masturbation after 2-7 days of sexual abstinence and analyzed within 1 hour at a certified andrology laboratory. Automated semen analyzers will be used to measure sperm concentration, motility, and morphology, while liquefaction time will be assessed visually. Quality control procedures, including periodic calibration of the analyzer and internal proficiency testing, are in place to ensure data reliability.

3. Statistical Considerations

   Sample Size Calculation:

   Based on a previous study reporting a 15% difference in primary outcome improvement between similar surgical methods, with 80% power and a two-sided significance level of 0.05, a total sample size of 284 patients (142 per group) was determined. Adjustments for potential dropout rates (estimated at 10%) have been incorporated.

   Missing Data Handling:

   For continuous variables with missing data, multiple imputation methods will be used, considering baseline characteristics and other relevant variables. For categorical data, the last observation carried forward approach may be applied depending on the nature of missingness.

4. Ethical and Safety Oversight

   Ethical Review:

   The study protocol has been reviewed and approved by the institutional ethics committee of Sichuan Provincial People's Hospital. An annual ethics review will be conducted to monitor any protocol deviations or emerging ethical issues.

   Safety Monitoring:

   An independent Data and Safety Monitoring Board (DSMB) will review interim safety data every 6 months. In case of a serious adverse event (SAE), such as testicular artery injury leading to ischemia, the DSMB can recommend immediate changes to the protocol, including halting the trial if necessary.

5. Dissemination Plan

In addition to publishing in peer-reviewed urology and andrology journals and presenting at national/international conferences, the study team will collaborate with patient advocacy groups to develop infographics and short videos summarizing the key findings. These materials will be made available on the hospital's official website and social media platforms to enhance patient education and awareness.