Adenomyosis: 5 things you need to know about the ‘evil twin sister’ of endometriosis

Despite increasing public awareness of endometriosis, with celebrity figureheads including Lena Dunham and Molly Mae, the condition’s ‘evil twin sister’, adenomyosis, remains neglected.

While the NHS has an entire webpage which explains what endometriosis is, there is currently no equivalent for its sister condition.

Read on for five things you should know.

It’s not the same as endometriosis

Both endometriosis and adenomyosis occur when the lining of the uterus (known as the endometrium) grows out of place, but there are major differences between the two.

In endometriosis, the rogue tissue invades areas outside of the uterus. While the extent of the growth varies from patient to patient, it can affect areas such as the bladder, bowel, ovaries, and even the lungs. Adenomyosis, on the other hand, causes the rogue tissue to bury inside the muscular wall of the uterus.

It’s possible to suffer from both conditions at the same time.

Symptoms include bloating, heavy periods, and pelvic pain

Thanks to the invasive endometrial growth, adenomyosis is characterised by an enlarged uterus. During menstruation, the embedded tissue swells and bleeds, typically causing a variety of symptoms (although some women are asymptomatic).

According to a patient leaflet published by University College Hospital, sufferers commonly have painful and irregular periods, with more than half experiencing heavy bleeding. Chronic pre-menstrual pain, and feelings of heaviness and discomfort in the pelvis are among other possible symptoms.

Less frequently, adenomyosis can cause bloating, pain during intercourse, and pain related to bowel movements. All symptoms should stop after the menopause.

It affects 1 in 10 women

The condition is believed to affect 10 per cent of women in the UK. That makes it just as prevalent as endometriosis, although it’s more common in women between the ages of 40-50, and those who have been pregnant before. While the cause of the condition is not known, UCH says that “genetics and some hormones may play a role”.

In terms of long-term effects, the North Bristol NHS trust says that adenomyosis does not appear to decrease the chance of pregnancy, however it has been linked to an increased risk of miscarriage and premature birth.

Treatment options are limited


For women with mild symptoms, trying to get pregnant, or nearing menopause, the North Bristol trust says that treatment may not be necessary, but for those seeking relief from symptoms, it recommends medication to reduce pain and bleeding, and hormonal interventions such as the contraceptive pill.

The only “cure” is a surgical procedure involving the removal of the womb (hysterectomy), although this is a last resort intervention. The Bristol-based trust also offers an alternative surgery which involves blocking the blood supply to the endometrial growth, forcing it to shrink, but neither procedure is advisable for women who want to get pregnant in the future.

It can take years to diagnose

The condition is typically diagnosed using MRI and ultrasound scans, but the NHS says that adenomyosis can take “a long time, even years, to diagnose” because “symptoms and severity can vary between women”.

The frequent dismissal of women’s gynaecological symptoms means that signs of adenomyosis may be conflated with ‘normal’ menstruation, or even other conditions such as endometriosis. Anecdotal reports of sufferers suggest that misdiagnosis is common.

Gabrielle Union, one of the only celebrities to have publicly identified as having the condition, suspects her condition went undiagnosed for years.

Speaking at a conference in 2019, Union explained: “The gag is I had [adenomyosis] in my early twenties, and instead of someone diagnosing me they were like ‘Oh you have periods that last nine or 10 days and you’re bleeding through overnight pads? Not a mere inconvenience... perhaps there’s something more there.’”

Earlier this year, the charity Tommy’s reported that the condition might be “underdiagnosed” after a review of existing studies found that “mild” cases could be missed by clinicians using current diagnostic methods.

“There should be training for clinicians and sonographers to diagnose adenomyosis using a standardised criteria,” said Dr Ishita Mishra, leader of the review.

“Being able to identify this condition using a uniform set of criteria would then help give us a true picture of the numbers affected, and better understanding of the impact of this condition,” Mishra explained.

If you have any health concerns, you should always contact your GP in the first instance.

There is also information available via NHS Scotland or Endometriosis UK.