Ejaculatory Behavior and Seminal Vesicle Size During Radical Prostatectomy (PreRP-EJAC)

November 25, 2025 updated by: National Taiwan University Hospital

Impact of Preoperative Ejaculation or Abstinence on Seminal Vesicle Size and Intraoperative Dissection Parameters During Radical Prostatectomy: A Randomized Controlled Trial

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

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

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.

Study Type

Interventional

Enrollment (Estimated)

40

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Taiwan
    • Outside U.S./Canada
      • Taipei, Outside U.S./Canada, Taiwan, 106
        • National Taiwan University Cancer Center
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

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.)

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Health Services Research
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Recent Ejaculation Group
Participants in this group will be instructed to have at least one ejaculation within 36 hours before surgery. Under anesthesia, they will undergo transrectal ultrasound (TRUS) to measure seminal vesicle volume prior to radical prostatectomy. Intraoperative dissection time, difficulty, and visual clarity will also be recorded.
Behavioral: Recent Ejaculation
Participants are instructed to ejaculate at least once within 36 hours prior to radical prostatectomy. This behavioral intervention is used to evaluate its effect on seminal vesicle volume and intraoperative dissection parameters.
Other Names:
  • Ejaculation within 36 hours before surgery
Active Comparator: Abstinence Group
Participants in this group will be instructed to abstain from ejaculation for at least 72 hours before surgery. Under anesthesia, they will undergo transrectal ultrasound (TRUS) to measure seminal vesicle volume prior to radical prostatectomy. Intraoperative dissection time, difficulty, and visual clarity will also be recorded.
Behavioral: Preoperative Abstinence
Participants are instructed to abstain from ejaculation for at least 72 hours prior to radical prostatectomy. This behavioral intervention is used to assess whether prolonged seminal vesicle filling affects intraoperative anatomy and dissection.
Other Names:
  • Ejaculatory Abstinence ≥72 hours

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Seminal vesicle volume measured by preoperative transrectal ultrasound (TRUS)
Time Frame: 12-14 hours before surgery (afternoon prior to operation)
Seminal vesicle volume is measured by the research investigator using transrectal ultrasound (TRUS) in the outpatient ultrasound room approximately 12-14 hours before surgery. Both vesicles are measured in three dimensions (length × width × height), and the average volume is calculated using the ellipsoid formula (L × W × H × 0.52). The values will be compared between groups with recent ejaculation versus abstinence.
12-14 hours before surgery (afternoon prior to operation)

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Dissection time of seminal vesicles during radical prostatectomy
Time Frame: During surgery (intraoperative)
The time required for bilateral seminal vesicle dissection is recorded in minutes from surgical video or intraoperative notes.
During surgery (intraoperative)
Surgical difficulty score of seminal vesicle dissection
Time Frame: Immediately after SV dissection during surgery
The primary surgeon rates the difficulty of SV dissection on a Likert scale from 1 (very easy) to 5 (very difficult), based on anatomical clarity and tissue handling.
Immediately after SV dissection during surgery
Intraoperative visual clarity score of seminal vesicles
Time Frame: During SV dissection, intraoperatively
The operating surgeon rates visual clarity of the surgical field (especially SV region) using a Likert scale from 1 (very poor) to 5 (excellent).
During SV dissection, intraoperatively
Seminal vesicle volume reported in postoperative pathology
Time Frame: Within 7 days after surgery (postoperative pathology report)
Pathology reports include three-dimensional measurements of both SVs. Final volume is calculated using the same ellipsoid formula and compared with TRUS findings.
Within 7 days after surgery (postoperative pathology report)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

National Taiwan University Hospital

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

December 1, 2025

Primary Completion (Estimated)

August 1, 2026

Study Completion (Estimated)

October 9, 2026

Study Registration Dates

First Submitted

November 17, 2025

First Submitted That Met QC Criteria

November 17, 2025

First Posted (Estimated)

November 24, 2025

Study Record Updates

Last Update Posted (Estimated)

December 3, 2025

Last Update Submitted That Met QC Criteria

November 25, 2025

Last Verified

October 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 202507191RINA

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

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.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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