What If Period Blood Holds the Missing Clues to Endometriosis?

For millions of women worldwide, endometriosis remains one of the most baffling and painful gynaecological conditions, partly because it can take years, or even a decade, to be officially diagnosed. Traditionally, doctors have had to rely on an invasive surgical procedure to confirm the condition. That, however, could soon change.

Researchers are now asking, what if menstrual blood isn't waste at all, but one of the most underused diagnostic tools in women's health? This shift in thinking is opening up new possibilities for diagnosing endometriosis.

Why has diagnosis been so hard?

Endometriosis is notoriously difficult to diagnose early. Symptoms vary widely, pain is often normalised, and many women are told for years that what they're experiencing is "just bad periods".

For some women, endometriosis symptoms can show up as intense period pain or pelvic pain that lingers even after the period ends. Others may notice very heavy or unpredictable bleeding, pain during sex, gut or bladder discomfort, or trouble getting pregnant. And then some women may have very few symptoms — or none that feel "serious enough" to flag early.

That wide range makes endometriosis hard to pin down. Many of these symptoms overlap with other conditions, and scans don't always catch what's going on. As a result, getting a clear diagnosis can take years, often involving surgery, leaving many women stuck in a long loop of doubt, dismissal, and waiting for answers.

Why period blood matters

Menstrual blood isn't just blood. It's a mixture of circulating blood, vaginal fluid, and material shed from the lining of the uterus (the endometrium). That combination makes it especially valuable to researchers. Because it comes directly from the uterus, menstrual blood contains cells and molecular signals that reflect what's happening inside the uterine environment.

These signals can carry information that other bodily fluids — including blood drawn from a vein — often miss. In that way, period blood can "speak" to clinicians differently, offering insights that are difficult to capture through routine tests. Simply put, it isn't just another blood sample. It's biologically distinct.

What is the new research actually doing?

Multiple research teams are already testing different ways to turn menstrual blood into a practical, at-home diagnostic tool for endometriosis.

One line of research is being led by a US-based femtech start-up that has been working with menstrual blood for several years. The team has collected samples using tampons and focused on analysing molecular signals within period blood, including DNA, RNA and proteins. Among these, messenger RNA (mRNA) has stood out as especially promising. Certain mRNA patterns appear consistently different in women with endometriosis compared to those without, suggesting a potential pathway for non-invasive diagnosis.

Running alongside this is work from a separate research initiative, which takes a more cell-focused approach. Instead of breaking menstrual blood down into molecules, researchers study whole, living cells shed during menstruation. They've identified differences in the number, shape and structure of specific cells in women with endometriosis. To preserve these cells, samples are collected using menstrual cups rather than tampons — reinforcing the idea that menstrual blood is biologically active, and not just dead cells!

Both approaches are still being tested and refined.

A bigger shift in women's health

Together, these efforts point to something larger than a single test. They reflect a shift in how women's health is being studied and taken seriously. Menstrual health was neglected for decades, but research interest and investment in this space are now growing.

Beyond endometriosis, researchers believe menstrual blood could eventually help detect other conditions such as adenomyosis, fibroids, polycystic ovary syndrome, and even certain cancers, many of which currently go undiagnosed for years or require invasive procedures to confirm.

In the coming years, what now seems like a science fiction dream, a quick, non-invasive test for endometriosis, may well become part of routine healthcare.