The goal of this clinical trial is to learn if recent ejaculation or abstinence before surgery affects seminal vesicle size and dissection-related surgical factors in adult men with prostate cancer undergoing radical prostatectomy. The main questions it aims to answer are:

Does ejaculation within 36 hours before surgery reduce seminal vesicle size compared to abstinence of 72 hours or more?

Does seminal vesicle size affect the ease or difficulty of surgical dissection during radical prostatectomy?

Researchers will compare an ejaculation group to an abstinence group to see if seminal vesicle volume and intraoperative surgical parameters differ between them.

Participants will:

Follow specific instructions to either ejaculate or abstain before surgery

Undergo a transrectal ultrasound (TRUS) to measure seminal vesicle size after anesthesia but before surgery

Have their surgical dissection time and difficulty rated by the operating surgeon

Radical prostatectomy (RP) remains a cornerstone treatment for localized prostate cancer. During RP, the anatomical dissection of seminal vesicles (SVs) can be challenging, and SV volume may influence intraoperative visibility, dissection ease, and the risk of complications.

Recent imaging studies suggest that ejaculatory activity significantly affects SV size. In particular, abstinence has been associated with larger SV volumes on MRI and TRUS, while ejaculation may lead to temporary SV shrinkage. These physiological changes, though well-documented radiologically, have not been systematically studied in a surgical setting.

This trial aims to explore whether ejaculatory behavior in the days before RP alters the surgical anatomy and impacts dissection-related metrics. Forty adult male patients with biopsy-confirmed prostate cancer, scheduled for RP, will be randomized in a 1:1 ratio into two groups:

Ejaculation group: At least one ejaculation within 36 hours preoperatively.

Abstinence group: No ejaculation for ≥72 hours before surgery.

Under anesthesia and prior to surgery, transrectal ultrasound (TRUS) will be performed to measure bilateral SV dimensions. The average volume will serve as the primary endpoint. Intraoperative outcomes include dissection time, visual clarity, and perceived difficulty rated by the primary surgeon using a Likert scale. SV volume from final pathology reports will also be collected and compared.

This is a low-risk, behavior-based interventional study involving no experimental drug or device. The main purpose is to assess whether preoperative sexual behavior can be optimized to improve surgical planning and efficiency. Alpha-blocker usage and other potential confounders will be documented and adjusted for in the analysis.

If significant anatomical or procedural differences are observed, findings from this study may inform future multicenter research and guide preoperative patient counseling for RP.

Inclusion Criteria:

• Male patients aged 18 years or older
• Histologically confirmed prostate cancer
• Scheduled for radical prostatectomy
• Able and willing to comply with assigned ejaculation or abstinence protocol
• Willing to complete preoperative questionnaire
• Willing to undergo transrectal ultrasound (TRUS) 12-14 hours before surgery
• Able to understand and sign informed consent

Exclusion Criteria:

• Prior bilateral seminal vesicle resection or congenital absence of seminal vesicles
• Anatomical abnormalities preventing SV identification
• Hormone therapy within 6 months before surgery
• Inability to recall ejaculation history in the past 3 days
• Inability to follow behavioral instructions or TRUS protocol
• Severe anorectal disease or history of anorectal surgery preventing TRUS
• Cognitive or psychiatric conditions impairing informed consent
• Incomplete data or poor-quality imaging
• Prior prostate cancer treatment
• Belonging to a vulnerable population (e.g., minors, prisoners, pregnant individuals, cognitively impaired, etc.)

Individual participant data (IPD) will not be shared due to institutional policies and IRB-approved protocols that limit data access to the research team. The dataset is small, single-center, and contains sensitive clinical and behavioral information. There is no current plan to develop a public repository or de-identified dataset for external use.

The operating surgeon was masked to the participant's group assignment. Group allocation was concealed until after surgery. Neither the participant nor the research investigator performing TRUS was masked.