This study aims to understand the biological causes of heavy menstrual bleeding related to the uterine lining and why it affects some people but not others.

You may be eligible for this study if you meet the following criteria.

Inclusion Criteria:

• Individuals ages 18-45
• Have a regular menstrual cycle (21-35 days)
• Not currently using hormonal medications, or willing to stop for study
• No known bleeding disorder diagnosis
• No known or suspected anatomical/structural abnormalities that could cause heavy menstrual bleeding (Uterine fibroids, polyps, adenomyosis, etc)
• No diagnosis of PCOS
• Willing to use study-provided disposable pads and tampons for one period

If you join the study, you may be asked to complete up to 2–3 in-person visits at OHSU’s Marquam Hill Campus, along with some at-home tracking:

1. Screening & Enrollment Visit (1–2 hours)

   • Review and sign the consent form

   • Answer questions about your medical history

   • Blood draw

   • Complete a bleeding questionnaire

   • Receive at-home ovulation test kits and instructions

   • Receive a menstrual bleeding tracking form (PBAC) and study-provided pads and tampons

2. Transvaginal (Pelvic) Ultrasound (if needed)

   • A low-risk imaging procedure to evaluate the uterus

   • Only required if you have not had one in the past 6 months

3. Endometrial Biopsy Visit (about 1 hour)

   • Scheduled 10–14 days after ovulation

   • Includes a pregnancy test, blood draw, and tissue sampling from the uterine lining

   • Optional medication may be offered to help you relax

You will also complete at-home ovulation testing and track menstrual bleeding for one cycle.

Participants can receive up to $400 for their time and effort:

• Screening Visit: $50
• Final Study Visit (Biopsy): $275
• PBAC Completion: $25

Additional perks include:

• Free bloodwork with results
• Free transvaginal ultrasound and provider consultation (if not done recently)
• Free parking
• Ride passes for the Portland Aerial Tram to and from study visits

There is no cost for you to participate in our research study.