Adenomyosis

Contents

1. Lining tissue invades the uterine wall
2. The symptoms resemble other conditions
3. Who is affected is uncertain
4. The cause has not been settled
5. Diagnosis long depended on surgery
6. The wait is measured in years
7. Treatment runs from medicines to hysterectomy

Candace Cooley has treated menstrual disorders and pelvic pain of many kinds, and adenomyosis tends to surface among them in an unremarkable way. Picture a woman in her forties at a routine gynecology visit. Asked if anything has changed, she mentions, as if it hardly mattered, that her periods have grown heavier and more painful since her pregnancies, that she now plans around the first two days of each cycle, and that her lower abdomen often feels full and swollen. She has assumed for years that this is simply what periods become with age. The scene is a composite, but each detail matches what the medical literature describes.

Lining tissue invades the uterine wall

Adenomyosis is a condition in which the endometrium, the tissue that lines the uterine cavity, grows into the myometrium, the muscle of the uterine wall. The NHS describes it as the lining starting to grow into the muscle in the wall of the womb.¹ Under the microscope, MyPathologyReport explains, a pathologist sees endometrial glands and supporting tissue sitting deep inside the muscle; the glands look like normal lining but are in the wrong place, and the surrounding muscle is often thickened, which is why the uterus can be enlarged.⁴ The 2011 review in Contemporary OB/GYN described the typical affected uterus as soft and evenly enlarged: about 80 percent weighed more than 80 grams, against roughly 50 grams for a typical uterus, though one with adenomyosis alone rarely passed 200 grams.⁷ The condition is not cancer and does not turn into cancer.⁴

The misplaced tissue still behaves like lining. The University of Greenwich factsheet notes that it reacts to the cyclical rise and fall of hormones, thickening, breaking down and bleeding, which is what links it to endometriosis, although in adenomyosis the tissue does not grow outside the uterus.² The related condition has its own article, endometriosis and the long wait for diagnosis.

The symptoms resemble other conditions

The NHS lists painful periods, sometimes severe enough to stop usual activities, and heavy bleeding, along with symptoms that can come at any point in the cycle: pelvic pain, bloating or a sense of heaviness in the abdomen, and pain during sex. Some people with adenomyosis have no symptoms at all.¹ The Greenwich factsheet adds periods that are both heavy and long lasting, and abdominal pressure.² The HOPE project at the University of Edinburgh explains the pain: the islands of lining inside the muscle become inflamed and bleed in step with the cycle.³ Heavy periods are a common thread, and the wider problem is taken up under heavy menstrual bleeding.

Figure

How often adenomyosis is found, and how often it is caught

Women with adenomyosis in some study estimates

20 percent

Prevalence when many samples of each removed uterus are examined

65 percent

Cases correctly diagnosed before surgery, in a review of the literature

15 percent

Who is affected is uncertain

Estimates vary because the condition is hard to confirm. The Greenwich factsheet gives a figure of 10 to 20 percent of women.² A 2011 review in Contemporary OB/GYN reported that some studies put the share at around 20 percent, but that when pathologists examine many samples from each removed uterus the figure rises as high as 65 percent.⁷ It is most often diagnosed in women between 30 and 50, and it is more common in women who have had children.⁴ The same review found that about 80 percent of women with the disorder had given birth, although the number of pregnancies did not track with how often it occurred.⁷

The cause has not been settled

According to the NHS, the cause is not clear.¹ The leading theory, as the 2011 review describes it, holds that the barrier between the lining and the muscle, which normally keeps glands out of the wall, breaks down and allows them in, a process thought to need estrogen, though the review noted that little evidence supported it.⁷ Edinburgh researchers suggest it may relate to healing after pregnancy or injury to the lining, with regrowth turning inward instead of outward, and that immunity, genes and hormones are likely involved.³ Prior uterine surgery, such as a cesarean birth or removal of fibroids, and inflammation of the uterus have also been linked to it.⁴

Figure

What tends to accompany adenomyosis

• Have given birth80
• Another disease process in the uterus80
• Fibroids50
• Endometriosis11

percent

Diagnosis long depended on surgery

For most of its history adenomyosis could be confirmed only after the uterus was removed. The 2011 review stated that the diagnosis could be made only by examining uterine tissue under a microscope, and cited a literature review in which only 15 percent of cases were correctly identified before surgery.⁷ It gave two reasons: many women have no symptoms unless another uterine problem is present, and other conditions overshadow it. More than 80 percent of women with adenomyosis had another disease process in the uterus, with fibroids in about half, which links this condition closely to uterine fibroids.⁷

Imaging has improved the picture without settling it. Edinburgh’s HOPE pages say a scan can show subtle signs, that an MRI is sometimes needed as well, but the only certain test is still a look at the uterus under the microscope after hysterectomy, which many women do not want and which is often inappropriate.³ In practice the route usually begins with questions about periods, a check of the abdomen for swelling and often an internal examination, followed by referral for an ultrasound or MRI, which can also rule out other causes.¹² For women who do not have surgery, diagnosis rests on symptoms and imaging findings.⁴

The wait is measured in years

A French study reported by Contemporary OB/GYN in 2026 followed about 6,950 women with endometriosis, adenomyosis or both, and found an average diagnostic delay of 11 years for adenomyosis.⁶ Longer delays were tied to more severe period pain before diagnosis, to seeing more health professionals, to presenting with several symptoms at once and to a family history of the condition or of chronic pelvic pain. Social circumstances mattered too: women who saw their financial position as comfortable were diagnosed about 1.4 years sooner, and unemployment added to the wait.⁶

Personal accounts fill in what the averages leave out. In a 2023 Guardian feature, one woman described almost 30 years of heavy, painful periods before her diagnosis at 43, much of it spent being told her pain had other causes; another was diagnosed within eight months, which the paper noted was unusual; a third had the condition confirmed by MRI after a long wait to be seen.⁵

Treatment runs from medicines to hysterectomy

The NHS lists treatments aimed at symptoms. A hormone releasing intrauterine system thins the lining and makes periods lighter and less painful, other hormonal treatments are an alternative, and tranexamic acid or anti inflammatory medicines can reduce bleeding and pain.¹ Edinburgh adds injections that bring on a temporary menopause by quieting the ovaries, usually as a short term measure, and notes that doing nothing may suit a woman approaching menopause.³ If these fail, surgery may follow: endometrial ablation to remove the lining, or hysterectomy.¹ MyPathologyReport also mentions procedures that reduce the blood flow to the uterus.⁴ The Office on Women’s Health lists adenomyosis among the reasons for hysterectomy, describing uterine walls that thicken and cause severe pain and heavy bleeding.⁸

Figure

The usual order of treatment

1. 01
   Symptom reliefHeat, a TENS machine and ordinary pain relief for period and pelvic pain.
2. 02
   Nonhormonal medicinesTranexamic acid or anti inflammatory drugs to reduce bleeding and pain.
3. 03
   Hormonal treatmentA hormone releasing intrauterine system that thins the lining, or other hormonal options.
4. 04
   SurgeryEndometrial ablation to remove the lining, or a hysterectomy.

The honest limit is that medicine still has no way to remove adenomyosis on its own. Edinburgh notes that it cannot be seen easily by eye and so cannot be cut out without removing the uterus.³ The 2011 review observed that symptoms usually returned within six months of stopping the menopause inducing injections.⁷ And without surgery, a diagnosis remains a well supported judgment from symptoms and images rather than a certainty. Which path makes sense for any one woman depends on her symptoms and plans, and is a decision for her to reach with her own clinician.