New Delhi: For millions of women, endometriosis turns periods into something far more debilitating than routine cramps, causing chronic pelvic pain, painful bowel movements, pain during sex, and, in many cases, years of undiagnosed suffering. Now, a new study by a French biotech company suggests menstrual blood could help doctors detect the disease earlier, without surgery.
The study, published in Nature Communications Medicine on 16 May, found that DNA methylation patterns in stem cells derived from menstrual blood could distinguish people with endometriosis from healthy individuals, potentially opening the door to a non-invasive diagnostic test.
Researchers at Endogene.bio identified more than 400 regions in the genome where these methylation patterns differed between women with and without endometriosis. Many of these regions were linked to genes involved in key features of endometriosis, including inflammation and abnormal growth.
For the study, Cristina Fernández-Molina and team isolated endometrial mesenchymal stem cells (eMSCs) — cells involved in repairing the uterine lining during each menstrual cycle — from the menstrual blood of 19 healthy women and 23 women with endometriosis. They then analysed the whole genomes of these samples to look for differences in DNA methylation patterns between the two groups.
DNA methylation is a process in which tiny chemical tags, called methyl groups, attach to DNA and influence how genes are switched on or off.
“This is a very interesting study. The work is new, but the numbers are very small; validation is needed in a larger and more heterogeneous group,” said Hugh Taylor, Chair, Obstetrics, Gynaecology and Reproductive Sciences, Yale School of Medicine, Connecticut, said in an email interview.
Developments in research
One of the leading theories behind endometriosis suggests that menstrual blood carrying these stem cells flows backwards through the fallopian tubes into the pelvic cavity, where the cells can implant, grow, and eventually form endometriotic lesions. Although the backward flow of menstrual blood, known as retrograde menstruation, occurs in nearly 90 per cent of women, only some go on to develop endometriosis.
“The idea that menstrual stem cells are epigenetically altered in endometriosis is an interesting finding, one that could explain why some retrograde menstruation leads to endometriosis but most does not,” said Taylor.
The team also trained machine learning models on these methylation signatures, which could predict disease status. They also found that some of the regions with increased DNA methylation seen in endometriosis were similar to those previously reported in conditions such as ovarian cancer, uterine fibroids, and other cancers.
Researchers around the world are also exploring several other non-invasive approaches to diagnose endometriosis earlier and more accurately. Many such efforts are focusing on inflammatory proteins, immune markers, and state-of-the-art imaging-based techniques.
“Many studies are looking at microRNA biomarkers of endometriosis in either blood or saliva that are better validated using larger numbers. Future larger studies in independent populations will determine which of the non-invasive biomarkers are most likely to succeed,” said Taylor.
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Most underdiagnosed gynaecological conditions
Endometriosis — a condition in which tissue similar to the uterine lining grows outside the uterus, often on the ovaries or fallopian tubes — has emerged as a major health concern.
For many, getting an accurate diagnosis can take anywhere between five and 11 years, if it happens at all. Delayed diagnosis often means years of unmanaged pain, repeated doctor visits, fertility complications, and a significant impact on mental health and quality of life.
Endometriosis has long puzzled clinicians and researchers alike. Scientists still do not fully understand how the disease develops and progresses. Part of the reason diagnosis is difficult is that symptoms and their severity vary widely from person to person.
“The severity of endometriosis can vary widely, and clinical symptoms do not always reflect how advanced the disease is. Someone with very large cysts may have no symptoms or pain at all, with the condition only being discovered incidentally during a routine health check,” said Vijeya Sherbet, Consultant Obstetrician, Manipal Hospital, Bengaluru.
Historically, the gold standard for diagnosing endometriosis has been laparoscopic surgery, an invasive procedure in which doctors remove tissue from the abdomen for a biopsy. Non-invasive tools such as Magnetic Resonance Imaging (MRI) scans and transvaginal ultrasounds can help detect the condition, but many cases still go undetected.
One reason is that superficial endometriosis — the most common form of the disease — can be particularly hard to spot. Instead of forming large cysts, it causes tiny, shallow lesions on the pelvic lining that are often difficult to see on ultrasound or even MRI scans.
“Endometriosis is often detectable on transvaginal ultrasound, particularly when it causes visible changes such as ovarian cysts, blood-filled fallopian tubes, or tissue thickening behind the uterus. In some cases, the disease may not form cysts at all, but instead cause inflammation or scarring, which may only become apparent during laparoscopy,” said Sherbet.
Despite affecting about 190 million women of reproductive age globally, endometriosis remains one of the most poorly understood and underdiagnosed gynaecological conditions. In India alone, it affects about 42 million women.
(Edited by Ratan Priya)