With average time to endometriosis diagnosis in the UK now 9 years 4 months, Hermione Blakiston from Sagentia Medical explains how clinical adoption of menstrual blood as a diagnostic sample could help accelerate the care pathway.
The gold standard for diagnosing endometriosis – laparoscopy – requires specialist expertise, which can contribute to diagnostic delays. Imaging techniques such as transvaginal ultrasound and MRI are often used beforehand, but their ability to detect the three endometriosis subtypes (superficial peritoneal, ovarian, deep infiltrating) varies.
Against this backdrop, several studies have analysed the diagnostic potential of non-invasive sample types including venous blood, saliva, and menstrual blood.
Studies based on menstrual blood report the identification of biomarkers with sensitivity of up to 95% and specificity of up to 90% across multiple endometriosis types. These figures compare favourably with many circulating blood biomarkers and highlight the potential of menstrual blood as a diagnostic sample.
With current evidence coming primarily from small, single-centre studies, tests based on menstrual blood will not replace laparoscopic or image-based diagnosis without further validation. However, sample-based diagnostics could enable faster rule-in or rule-out decisions, supporting earlier and more targeted clinical interventions. These might include justification for hormonal or pain-management therapies, more informed decisions about invasive procedures, and clearer differentiation between endometriosis and other conditions with similar symptoms, such as uterine fibroids, ovarian cysts, pelvic inflammatory disease, or irritable bowel syndrome.
Menstrual blood as a diagnostic sample
Menstrual blood contains endometrial cells, immune components, and inflammatory markers shed directly from the uterus, which offers unique insight into the endometrial environment. This has prompted growing interest in the use of menstrual blood as a diagnostic sample.
A Research OutSmarts Endometriosis (ROSE) study applied single-cell RNA sequencing to fresh menstrual blood samples, revealing differences in stromal cell activity linked to endometriosis. Additional studies suggest that lipid profiles in dried menstrual blood may serve as viable indicators.
Translating this potential into clinical diagnostics will depend on more than biomarker discovery. It will also require reliable ways to collect menstrual blood samples.
Several start-ups and research organisations are innovating around the use of biomarkers found in menstrual blood for diagnostic purposes. Samples are collected using various techniques from cups, sponges, pads and tampons to direct sampling methods.
Self-collection of menstrual blood samples that are sent to a lab or dropped off at a clinic for analysis could provide an accessible, patient-centred pathway to diagnosis. However, the current lack of standardisation in sample collection and storage could be a limiting factor.
Variability in the way samples are handled can be a considerable source of bias and measurement error. And absorbent methods are potentially more challenging from a processing perspective – analysis in a central lab would likely require extensive pre-analytical and analytical steps.
Sample collection, preservation, and processing challenges become even more significant when exploring point-of-care or at-home formats such as lateral flow testing (LFT).
Translating menstrual blood diagnostics into lateral flow tests A 2025 study demonstrated an interesting LFT concept for endometriosis diagnosis. The research describes a borophene nanosheet-based LFT capable of ultrasensitive, rapid detection of the HMGB1 protein, which is associated with endometriosis, in menstrual blood.
The authors suggest that the test could be integrated into menstrual pads to provide a ‘pregnancy-test-like’ user experience. However, the study does not define sample collection protocols or a diagnostic pathway. Practical considerations like these can determine whether promising non-invasive biomarkers can be used as the basis for reliable clinical tools.
Several potential workflows based on a range of sample collection technologies, including established formats and emerging concepts, illustrate how a lateral flow approach might be implemented in practice. For example:
Pre-treated sampling pad
A menstrual pad embedded with filtration materials, buffer salts, and surfactants that condition the sample during wear. After use, the pad – or a detachable section – could be sent to a central laboratory for analysis or deposited at a pharmacy or clinic. This approach offers convenient at-home sample collection while allowing results to be communicated through clinical channels.
Removable in-pad test strip
Alternatively, a wearable pad could include a lateral flow strip that is removed after use and inserted into a test cassette. A pre-measured buffer would then be applied to activate the assay. This approach would reduce the complexity and cost of consumables, but it would introduce additional user steps and would have to accommodate variability in sample age.
Diagnostic pen
A pen-like device fitted with a sampling wick could collect menstrual blood directly from the vaginal opening. A cap containing a pre-measured buffer would initiate lateral flow through the device (e.g., through a pierced membrane mechanism). This format could provide a way to analyse fresh samples with a user experience similar to that of a pregnancy test.
Swab-based test kit
Adapting the workflows of rapid COVID-19 testing, a swab could be used to collect menstrual fluid from a minimally absorbent pad. The swab would then be suspended in buffer and applied to the lateral flow device. While this method involves more steps, it would benefit from user familiarity and a fast, straightforward process.
Earlier diagnosis and more effective intervention
While these potential workflows are interesting, it is of course important to consider Positive Predictive Value (PPV) and Negative Predictive Value (NPV). Too many false positives would overload the system with unnecessary follow-ups, and false negatives could delay treatment. What’s more, a single test might not cover all endometriosis presentations.
Nevertheless, strong performance for the most common subtype (superficial peritoneal) could significantly improve care for many women.
Addressing practicalities of menstrual blood collection
The diagnosis of endometriosis remains a difficult women’s health challenge. Non-invasive diagnostics based on menstrual blood represent an opportunity to shorten diagnostic timelines and support earlier clinical decision-making. However, translating promising biomarkers into practical diagnostic tools takes more than proving analytical performance. The reliable collection, stabilisation, and processing of menstrual blood is a major technical barrier, especially if samples are collected and processed outside traditional clinical settings.
For MedTech developers in this space, sample collection needs to be a central consideration. Patient-centred, thoughtfully designed technologies will play a critical role if menstrual blood is to make the transition from an interesting research sample to a viable clinical diagnostic. Addressing these challenges could help transform the pathway to endometriosis diagnosis, enabling women to get treatment for this complex, painful condition sooner.
