Blood test to diagnose endometriosis

3 April 2019

In a press release yesterday MDNA Life Sciences announced that they have developed a blood test that may diagnose endometriosis in nine out of ten of cases.

This testing kit, which MDNA suggests will be available to buy privately within nine months, would – theoretically – enable women with concerns about endometriosis-like symptoms to discover whether or not they are likely to have the disease.

Endometriosis is notoriously difficult to diagnose and, due to a “normalisation of symptoms” combined with a reluctance to perform unnecessary surgery, women often experience an unacceptably long delay between the onset of symptoms until they are diagnosed and treated.

A non-invasive diagnostic test is an unmet clinical need and would be welcome progress in the under-researched field of endometriosis.

The science behind the Mitomic Endometriosis Test

The Mitomic Endometriosis Test, which was developed at MDNA’s Newcastle lab, looks for biomarkers of endometriosis in the blood through the close examination of mutations in mitochondrial DNA.

The Oxford Endometriosis CaRe centre provided samples for the study but were not involved in analysis or interpretation of results, and are not co-authors on the MDNA paper [1] nor co-developers of the test.

The MDNA investigators found that these newly-identified biomarkers can detect endometriosis in blood samples in up to nine out of 10 cases, even in the early stages of the condition [1].

This means that there is a 10% risk of receiving a false negative diagnosis (ie. to be told that you don’t have endometriosis, even though you do) or a false positive diagnosis (ie. to be told that you have endometriosis, even though you don’t). This is not dissimilar to a diagnostic laparoscopy, where the diagnosis is dependent on the curiosity of the surgeon and the pathologist!

However, the study upon which the test was developed included a very small sample size of symptomatic women with endometriosis and controls (= women without endometriosis) so should be viewed with caution. We know that women with endometriosis are a very diverse population; therefore, any diagnostic test will have to demonstrate if it is useful for all types of endometriosis, or whether it only works for a specific type.

The test would, therefore, need to to be replicated in a much larger, independent, sample set covering a much wider and more diverse set of demographics of women before claims of a real breakthrough can be made.

Real or false hope?

Firstly, the test is not yet available, and when it does become available in the United Kingdom it will cost £250. It is unclear when the test will be available in other countries.

Secondly, caution should be heeded, as we need to see robust validation evidence in an independent set of samples before we can jump to any conclusions regarding the results and the promise of any diagnostic test. Only then will we know whether the Mitomic Endometriosis Test is a true and accurate blood test available to diagnose endometriosis in all populations.

In conclusion, the combined statement by the World Endometriosis Society and World Endometriosis Research Foundation released last year therefore continues to be an accurate status quo of diagnostic biomarkers for endometriosis.