Ejaculatory Behavior and Seminal Vesicle Size During Radical Prostatectomy

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.)