New Saliva and Blood Tests Claim to Diagnose Endo. Here Is What You Should Know.

What the latest evidence says about Ziwig Endotest, EndoSure, and HerResolve

If you have endometriosis, or are still searching for answers about your symptoms, you may have seen recent news headlines about new non-invasive tests claiming to diagnose endometriosis without surgery.

As endometriosis specialists, we welcome research like this. Patients have waited far too long for answers, and advances in non-invasive testing have the potential to shorten the diagnostic delay that has affected millions of women.

Our patients are asking about these tests, and they deserve an honest answer about what we know today.

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What the Tests Are

Several tests have received significant attention. None are FDA-cleared for diagnosing endometriosis in the United States. Their published results are encouraging, but each still has important evidence gaps. The UK’s National Institute for Health and Care Excellence (NICE), a public body that evaluates medical evidence to guide NHS care, has concluded that more research is needed before these technologies can be widely adopted.

Ziwig Endotest is a saliva test developed in France that analyzes a signature of 109 microRNAs using next-generation sequencing and artificial intelligence. A prospective multicenter validation study published in NEJM Evidence in October 2025 enrolled 971 symptomatic women ages 18 to 43 across 17 French centers. The test correctly identified 97.3% of participants with endometriosis and correctly ruled it out in 94.1% of those without it. However, 77% of participants had endometriosis, reflecting a population already at high risk for the disease. As a result, the test’s performance in general gynecology or primary care settings, where endometriosis is less common, remains uncertain. The study was funded through unrestricted grants from Ziwig. The test has European regulatory authorization and is reimbursed and available by prescription in France. The company reports availability in other countries as well.

EndoSure uses abdominal electrodes to measure gastrointestinal myoelectrical activity during a water-load protocol. The company proposes that endometriosis produces a detectable pattern in gut electrical activity. A prospective, open-label study of 154 women published in the Journal of Clinical Medicine in 2024 reported sensitivity between 91% and 95% and specificity between 95% and 96%, depending on age and the model used. In practical terms, it identified roughly 9 out of 10 participants with endometriosis and correctly ruled it out in about 19 out of 20 without it. The study was relatively small, and the lead author disclosed that he founded EndoSure, serves on its board, and holds a patent licensed to the company. NICE has issued draft guidance allowing limited NHS use for three years while additional evidence is collected, particularly after negative, inconclusive, unsuitable, or declined ultrasound.

HerResolve, developed by HerAnova Lifesciences, is a blood test that combines three microRNAs, three protein biomarkers, one steroid hormone, age, and body mass index in a machine-learning model. A study published in the Journal of Minimally Invasive Gynecology in 2026 included 298 women. Researchers developed the model using 218 participants, then tested it retrospectively in a separate group of 80 women, including 40 with endometriosis and 40 controls. In that smaller validation group, it detected 80% of endometriosis cases and correctly ruled out the disease in 97.5% of controls. It also detected 61.5% of surgically and histologically confirmed cases that had not been identified by routine transvaginal ultrasound, MRI, or both. The validation cohort was small and retrospective, and broader prospective validation is still underway.

How to Interpret These Results

Sensitivity describes how often a test correctly detects disease. A test with 80% sensitivity would identify about 8 of every 10 people who have endometriosis and miss about two.

Specificity describes how often it correctly rules disease out. A test with 97.5% specificity would correctly return a negative result for about 39 of every 40 people who do not have endometriosis.

These figures do not tell an individual patient the probability that their result is correct. That also depends on how common endometriosis is in the population being tested. Studies conducted in specialist centers, where most participants already have a high likelihood of disease, may not predict performance in primary care or among people with less typical symptoms. NICE has specifically identified this as an unresolved evidence gap for these technologies.

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What a Researcher Would Ask

Of the three, Ziwig currently has the largest prospective external-validation study. Its results are notable, but the study was entirely industry-funded, and conducted among symptomatic patients in specialist settings where 77% had endometriosis. Independent replication in populations with lower disease prevalence remains important.

EndoSure has more than one published accuracy study, but the peer-reviewed evidence remains limited, and the technology’s founder and patent holder led the principal 154-person study. NICE concluded that its accuracy in primary care, risk of false results, and effects on patient outcomes remain uncertain.

HerResolve produced strong specificity but lower sensitivity than the other two tests. Its headline accuracy figures came from only 80 retrospectively selected participants, not the full 298-person study population. Larger prospective studies are needed to determine how it performs in routine clinical practice.

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What Professional Guidelines Say

Current professional American guidelines have not yet incorporated these new tests.

ACOG’s 2026 clinical practice guidelines explicitly recommend against using blood tests, urine tests, or other biomarkers to diagnose endometriosis. No other major American professional society, including ESHRE, ASRM, or AAGL, currently endorses routine clinical use of any non-invasive molecular test for endometriosis.

NICE took a different but cautious approach in July 2026. Its draft guidance permits EndoSure and Ziwig Endotest to be used in selected NHS primary-care patients during a three-year evidence-generation period. NICE emphasized that the tests should supplement standard care, not replace clinical judgment, and that their accuracy and effects on patient outcomes in primary care are still uncertain.

What These Tests Cannot Tell you

These tests aim to estimate whether endometriosis is present. They cannot reliably show where lesions are located, how extensive the disease is, whether the bowel, bladder, ureters, diaphragm, or other structures are involved, or what a potential operation may require.

A positive result may support a clinical diagnosis or referral, but it cannot replace specialist imaging when deep infiltrating disease mapping is needed. A negative result also cannot completely exclude endometriosis, because none of these tests has 100% sensitivity.

Where Things Stand

The search for a reliable noninvasive endometriosis test is one of the most encouraging areas of current research. Ziwig has produced the largest prospective validation study, while EndoSure and HerResolve offer different physiological and blood-based approaches that merit further investigation.

These tests need independent replication and evaluation in primary care and more diverse populations. NICE found that those clinical-outcome data do not yet exist.

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For now, these technologies are promising additions to the diagnostic conversation, but they are not substitutes for a careful clinical evaluation or individualized treatment planning.

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