Endometriosis, a condition in which tissue similar to the uterine lining grows outside the uterus, affects an estimated one in ten women of reproductive age. However, diagnosing the disease remains a significant challenge, often taking an average of seven to nine years. Many patients endure severe pain misattributed to normal menstrual cramping or psychological causes before receiving a confirmed diagnosis. Currently, the definitive diagnosis typically requires invasive surgery, as imaging techniques such as MRI or ultrasound frequently fail to detect lesions reliably.
Several start-ups have introduced noninvasive diagnostic tests designed to identify biomarkers associated with endometriosis through saliva, blood, or gastrointestinal measurements. Despite the appeal of these alternatives, none have received approval from the U.S. Food and Drug Administration (FDA). Instead, the tests are marketed for research purposes or through regulatory pathways that the FDA continues to scrutinize.
Among the emerging tests are Endotest, which analyzes microRNA patterns in saliva; EndoSure, which measures electrical activity in the gastrointestinal tract; EndomTest, which detects specific proteins in the blood; and a product from Xella Health, which uses artificial intelligence to assess blood biomarkers, symptoms, and medical history. Xella is also developing a menstrual fluid-based test, although the data underpinning it remain limited and unpublished.
Initial manufacturer-backed studies suggest promising accuracy for some of these tests. Endotest reported more than 90 percent accuracy identifying individuals with and without endometriosis in a study involving 971 participants, while EndoSure demonstrated similar figures in a smaller group of 154. However, experts caution that these studies may be subject to bias due to the high prevalence of endometriosis in the study populations, potentially inflating the tests' performance.
Independent evaluations have yielded more cautious findings. A small independent study of Endotest showed less robust results, and limited research on EndoSure outside of manufacturer-related studies remains unverified and lacks sufficient control groups. EndomTest’s protein-based approach performed unevenly in early trials, identifying only 46.2 percent of cases while producing almost no false positives, though some experts remain skeptical given its reliance on proteins elevated in multiple diseases.
Experts acknowledge the potential of microRNA-based diagnostics, noting their growing research base, but also emphasize that technologies assessing gastrointestinal electrical activity require further validation. They warn that noninvasive tests, even if validated, may not capture the lesion location or severity information that surgical diagnosis provides. False negatives pose a particular concern, potentially delaying care for patients already struggling with prolonged diagnostic uncertainty.
A British health agency is considering temporary adoption of Endotest within the National Health Service to gather more real-world data, but officials indicated that other novel tests are not yet ready for similar deployment.
Meanwhile, large clinical trials continue. One such study, examining a microRNA blood test called DotEndo developed with FDA consultation, could lead to regulatory approval by 2027. Researchers also are investigating how biomarkers differ between adolescents and adults with endometriosis, which may influence future testing approaches.
Until noninvasive diagnostics are validated, medical professionals emphasize relying on clinical evaluations and patient symptoms to guide treatment. Many experts assert that listening more carefully to patients’ experiences could expedite diagnosis and improve care in the near term.