Introduction Phlebotomy, or venipuncture, is a minimally invasive procedure commonly used in routine medical practice and research for blood collection. While generally safe when conducted according to standardized measures, it carries risks like hematomas and vasovagal reflex for patients, and bacterial infection for healthcare workers. The invasiveness of phlebotomy depends on factors like patient age, volume of blood drawn, and collection frequency. Ethical guidelines, including those in Japan, require informed consent and safety measures in research, emphasizing the need for scientific or societal justification. This study aims to assess phlebotomy’s invasiveness across various research scenarios to better understand its implications.

Methods An online questionnaire survey was conducted among Certified Research Ethics Committee Professionals (CRePs) in Japan, who are experts in research ethics. These professionals check research protocols to ensure compliance with legal requirements and standards and provide necessary information for ethical committee reviews. The survey was conducted in September 2024. The questionnaire included four scenarios: healthy adult, healthy minor, adult patient, and minor patient, asking respondents to define the invasiveness threshold based on the amount of blood drawn or the number of collections.

Result A total of 77 CRePs participated in the survey, with most respondents serving on the ethics committees of academic institutions (72%) and possessing significant experience, 73% reported serving 5 or more years. For healthy adults, 50% of respondents considered 20 mL of blood invasive, while 30% identified 50 mL as the threshold; for adult patients, the responses were similar, though more considered 200 mL or always minimally invasive. Regarding frequency, a few times was the most common threshold for invasiveness, followed by once and several times, showing higher tolerance for patients. For minors, responses leaned more toward always invasive, especially for healthy children, with thresholds increasing for patient cases. Age-related invasiveness criteria varied widely, with significant caution for non-patients.

Discussion This study explored the invasiveness of phlebotomy in medical research under Japanese ethical guidelines, highlighting its classification as a minimally invasive procedure. Phlebotomy’s invasiveness is influenced by factors such as patient age, volume of blood drawn, and number of collections, with ethical considerations being particularly important in research contexts. The findings revealed differing opinions among CRePs, who are well-versed in research protocols, especially regarding minor versus adult cases. Interventions for mitigating pain and anxiety during phlebotomy, particularly in children, were emphasized, along with the need to distinguish between research-related phlebotomy and blood donation standards due to differing objectives.

Conclusion Opinions regarding the invasiveness of phlebotomy for research purposes vary by the amount of blood drawn and number of collections. In general, phlebotomy is considered invasive if the blood is drawn from a minor.

The authors have declared no competing interest.

This study was funded by Japan Agency for Medical Research and Development (AMED)

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