Adenomyosis affects roughly one in five women seen in a general gynecology clinic, based on a large prospective study using transvaginal ultrasound, though reported rates swing wildly depending on who is being studied and how the diagnosis is made. That single number hides a surprisingly messy reality: for decades, adenomyosis could only be confirmed after a hysterectomy, which meant the condition was systematically studied in people who were already sick enough to have their uterus removed. Modern imaging has started to change that picture, but it has also revealed just how variable the condition is across age groups, symptom profiles, and populations.
What the Prevalence Numbers Actually Mean
The most commonly cited figure comes from a prospective study of 985 women attending a gynecology clinic in the UK. Using transvaginal ultrasound, researchers found adenomyosis in about 21% of participants. That number sits in the middle of a wide range: older studies based on hysterectomy specimens reported rates anywhere from 5% to over 70%, depending on how aggressively pathologists looked for it and what surgical population was sampled.1Human Reproduction. How common is adenomyosis? A prospective study of prevalence using transvaginal ultrasound in a gynaecology clinic The hysterectomy-based numbers almost certainly overestimate prevalence, because people undergoing hysterectomy tend to have more severe symptoms and more uterine pathology than the general population.
When researchers look at populations defined by specific symptoms, the numbers shift again. A study of 373 women referred for pelvic symptoms found adenomyosis on ultrasound in about 12%.2PubMed Central. Prevalence of endometriosis and adenomyosis at transvaginal ultrasound examination in symptomatic women That lower figure may reflect a different mix of referral reasons, since the study included women with various gynecological complaints and nearly half had completely normal ultrasound findings. The takeaway is that no single prevalence figure applies universally. Whether the answer is “one in five” or “one in eight” depends on the population being screened and the imaging criteria used.
Why Diagnosis Makes Prevalence So Hard to Pin Down
Adenomyosis involves tissue resembling the uterine lining growing into the muscular wall of the uterus. Unlike a fibroid, which forms a discrete lump, adenomyosis can be diffuse and subtle, making it harder to spot on imaging. For a long time, the only way to confirm it was to examine uterine tissue under a microscope after hysterectomy, which meant the condition went undiagnosed in anyone who did not have surgery.
Imaging has improved substantially. Transvaginal ultrasound and MRI can now detect adenomyosis without surgery, but the criteria for what counts as a positive diagnosis have been debated. An international consensus project called MUSA (Morphological Uterus Sonographic Assessment) recently refined the ultrasound features that indicate adenomyosis, dividing them into direct signs, like tiny cysts within the muscle wall and echogenic islands, and indirect signs, like asymmetric thickening of the uterine wall and abnormal shadowing patterns.3PubMed. Consensus on revised definitions of Morphological Uterus Sonographic Assessment (MUSA) features of adenomyosis: results of modified Delphi procedure A validation study has since tested these revised criteria for diagnostic accuracy.4PubMed. Validation of the revised MUSA criteria for sonographic detection of adenomyosis
MRI offers a complementary approach. One of the key measurements is the thickness of the junctional zone, a transitional layer between the uterine lining and the outer muscle. In people with adenomyosis, this zone is substantially thicker. One study found an average junctional zone thickness of about 14 mm in people with the condition, compared with roughly 6 mm in those without it.5PubMed Central. The Significance of MRI Evaluation of the Uterine Junctional Zone in the Early Diagnosis of Adenomyosis This measurement has been described as a reliable non-invasive marker for the condition and may even predict other uterine pathologies.6PubMed. Junctional zone thickness on magnetic resonance imaging – a non-invasive diagnostic method for adenomyosis and beyond
The practical consequence of all this diagnostic variability is that prevalence figures are only as reliable as the imaging criteria and the skill of the person reading the scan. Two clinicians looking at the same ultrasound might disagree on whether adenomyosis is present, particularly in mild or early cases. That ambiguity filters directly into the published prevalence data.
Age and Adenomyosis in Younger People
Adenomyosis has traditionally been described as a condition of women in their 30s and 40s, often discovered around the time of hysterectomy. But improved imaging has revealed that it shows up earlier than many clinicians expected. In a study of adolescents and young women aged 12 to 20, about 5% showed ultrasound signs of adenomyosis. When the sample was limited to those with painful periods, the rate climbed to nearly 9%, and it reached almost 14% in those with heavy menstrual bleeding.7PubMed Central. Adenomyosis and Adolescence: A Challenging Diagnosis and Complex Management
Among adolescents and young women specifically reporting severe period pain, the numbers are higher still. One study of 271 participants aged 12 to 25 with severe pain found ultrasound signs of adenomyosis in about 18%, with the rate reaching roughly 26% among those who also had heavy bleeding.7PubMed Central. Adenomyosis and Adolescence: A Challenging Diagnosis and Complex Management A separate study found that in young women aged 20 to 24, the prevalence of adenomyosis was higher than in adolescents aged 14 to 19, with adenomyosis present in 46% of those with pelvic pain.8PubMed. Adenomyosis and endometriosis in adolescents and young women with pelvic pain: prevalence and risk factors Both trends point in the same direction: the condition seems to progress with age, and younger people with severe symptoms are more likely to have it than those without.
This matters because adenomyosis is still under-recognized in younger patients. A teenager with painful, heavy periods is more likely to be told the problem is “just bad periods” than to receive a focused ultrasound evaluation for adenomyosis. As awareness grows, earlier diagnosis may lead to earlier treatment and better outcomes.
Known and Suspected Risk Factors
Identifying risk factors for adenomyosis has been difficult precisely because the diagnosis was historically tied to hysterectomy. Still, several associations have emerged from the available evidence, though the strength of each varies.
Prior uterine surgery is one of the more consistently reported risk factors. A study comparing women with and without adenomyosis found that a history of any prior uterine surgery was more common in those with the condition, with the association remaining significant even after adjusting for other factors.9PubMed. Is prior uterine surgery a risk factor for adenomyosis? The thinking is that surgical disruption of the boundary between the uterine lining and the muscle wall could allow endometrial tissue to invade deeper. This fits with the broader theory that mechanical trauma to that interface plays a role in the disease.
Interestingly, some factors that seem like obvious candidates do not hold up as clearly as expected. A case-control study of women with infertility found no significant difference in rates of prior pregnancy, number of births, or miscarriage between those with and without adenomyosis.10Journal of Medicinal and Chemical Sciences. Uterine Adenomyosis Relationship with Gravidity, Parity, and Abortion in Women with a History of Infertility: A Case-Control Retrospective Study The same study found no difference in the frequency of primary versus secondary infertility between the two groups. While other research has suggested that higher parity (having had more pregnancies carried to term) is associated with adenomyosis, the evidence is inconsistent enough that it is not a settled risk factor.
Environmental exposures are an area of growing but still limited research. A review examining the potential role of endocrine-disrupting chemicals noted that while there is substantial evidence linking such chemicals to endometriosis, very few studies have directly examined whether they also raise the risk of adenomyosis.11PubMed Central. The Potential Relationship Between Environmental Endocrine Disruptor Exposure and the Development of Endometriosis and Adenomyosis Given the biological similarities between the two conditions, exposure to hormone-disrupting chemicals remains a plausible but unconfirmed contributor.
Genetic and epigenetic factors are also under investigation. Research has highlighted the involvement of estrogen signaling pathways, inflammatory pathways, and changes in how DNA is read and regulated, including altered DNA methylation and chromatin remodeling.12PubMed Central. Genetic and Epigenetic Components in the Pathogenesis of Adenomyosis and Endometriosis in Adolescents These findings suggest a genetic susceptibility component, but no single gene or variant has been identified as a strong predictor.
How Adenomyosis Develops
The most widely accepted explanation for how adenomyosis begins centers on the Tissue Injury and Repair (TIAR) theory. The basic idea is that repeated mechanical stress at the boundary between the uterine lining and the muscle wall triggers a cycle of damage and healing that gradually goes wrong.13PubMed Central. Transitional Lesions, One More Step Towards Understanding the Pathogenesis of Adenomyosis That boundary, the junctional zone, is where the uterus generates the rhythmic contractions involved in menstruation and embryo transport. In some people, excessive or chronic contractions cause tiny injuries at this interface. The repair process ramps up local estrogen production, which in turn drives more contractions, creating a self-reinforcing loop.14PubMed Central. The pathophysiology of endometriosis and adenomyosis: tissue injury and repair
Over time, this cycle leads to fragments of the uterine lining being pushed deeper into the muscle wall, where they continue to respond to hormonal cycles, causing inflammation, pain, and heavy bleeding. Research on early “transitional” lesions supports this progressive model, showing tissue changes consistent with a stepwise invasion of the muscle wall rather than a sudden event.13PubMed Central. Transitional Lesions, One More Step Towards Understanding the Pathogenesis of Adenomyosis An important component of this theory is the abnormal local production of estrogen, which distinguishes adenomyosis-affected tissue from normal myometrium and may explain why the condition tends to worsen over reproductive years.15PubMed Central. An Appraisal of the Tissue Injury and Repair (TIAR) Theory on the Pathogenesis of Endometriosis and Adenomyosis
The Overlap With Endometriosis and Fibroids
Adenomyosis rarely travels alone. Its most frequent companions are uterine fibroids and endometriosis, though the degree of overlap depends on how and where the data are collected. In a large administrative dataset, about 48% of people diagnosed with adenomyosis also had fibroids, and 18% had endometriosis.16American Journal of Obstetrics and Gynecology. Adenomyosis incidence, prevalence, trends, and treatment A study of over 5,600 cases found that uterine fibroids were the most common concurrent condition at roughly 57%, followed by endometrial cancer at about 12% and endometriosis at about 11%.17PubMed Central. Endometrial carcinoma risk prediction and gynecological comorbidity in adenomyosis: a 5648-case study
The connection with endometriosis is particularly interesting because the two conditions may share underlying causes. One MRI-based study reported that over 90% of people with endometriosis also had signs of adenomyosis, and about 81% of those with adenomyosis also had endometriosis.18PubMed Central. Adenomyosis and endometriosis. Re-visiting their association and further insights into the mechanisms of auto-traumatisation. An MRI study That study focused on a population undergoing detailed MRI evaluation, so the overlap is likely inflated compared to the general population. A more recent study using pathology-confirmed cases found that among people with confirmed endometriosis who also underwent hysterectomy, about 56% had adenomyosis on histological examination.19Journal of Endometriosis and Uterine Disorders. Concurrent rates of pathology confirmed adenomyosis and endometriosis
The overlap with fibroids creates a clinical challenge. Both conditions cause heavy bleeding and pelvic pain, and both can enlarge the uterus. When someone has both, it can be difficult to determine which condition is driving the symptoms, which complicates treatment decisions.
Effects on Fertility and Pregnancy
Whether adenomyosis impairs the ability to conceive is a question many people understandably want answered. The picture is nuanced. In one prospective study of women undergoing IVF with donor eggs (which removes egg quality as a variable), implantation rates and clinical pregnancy rates did not differ significantly between those with and without adenomyosis. However, the miscarriage rate was roughly double in the adenomyosis group, at about 35% compared with 18%.20Fertility and Sterility. Impact of adenomyosis on in vitro fertilization outcomes in women undergoing donor oocyte transfers: a prospective observational study This suggests the problem may be less about getting pregnant and more about staying pregnant.
The specific ultrasound features of adenomyosis may matter, too. A study evaluating MUSA features in people undergoing IVF found that an interrupted junctional zone was the only feature independently linked to lower chances of clinical and ongoing pregnancy and a higher risk of early pregnancy loss.21PubMed Central. Association of revised morphological uterus sonographic assessment (MUSA) features of adenomyosis and IVF outcomes Not all adenomyosis looks the same on imaging, and the form it takes may predict reproductive outcomes better than a simple yes-or-no diagnosis.
For those who do conceive, adenomyosis has been linked to a range of pregnancy complications. A systematic review and meta-analysis found that adenomyosis carried over three times the odds of preterm delivery and a similarly elevated risk of having a baby that is small for gestational age, with the risk exceeding even that seen with endometriosis alone.22PubMed. Endometriosis and adenomyosis are associated with increased risk of preterm delivery and a small-for-gestational-age child: a systematic review and meta-analysis Other complications associated with the condition include premature rupture of membranes, placental detachment, restricted fetal growth, and preeclampsia.23PubMed Central. Increased risk of obstetric complications in patients with adenomyosis: A narrative literature review These risks do not mean a healthy pregnancy is impossible with adenomyosis, but they do mean closer monitoring is warranted.
The Shift Away From Hysterectomy
For much of the condition’s medical history, hysterectomy was the definitive treatment. It still works, in the sense that removing the uterus eliminates adenomyosis entirely. But it is irreversible, and many people diagnosed with the condition are still in their reproductive years and want to preserve the option of pregnancy. The trend in treatment has been moving steadily toward uterus-sparing approaches.24PubMed Central. Management of uterine adenomyosis: current trends and uterine artery embolization as a potential alternative to hysterectomy
Non-surgical options include hormonal treatments like progestins, GnRH agonists, and levonorgestrel-releasing intrauterine devices, all of which aim to suppress the hormonal cycle that fuels the disease. Surgical excision of adenomyosis tissue while preserving the uterus is technically possible but complex, carries meaningful risks, and is associated with substantial recurrence rates.25Current Obstetrics and Gynecology Reports. Non-surgical Treatment of Adenomyosis Newer interventional options like uterine artery embolization and MRI-guided focused ultrasound ablation are being explored as non-invasive alternatives that may help control symptoms while preserving the uterus.26Наука и здравоохранение. MAGNETIC RESONANCE-GUIDED FOCUSED ULTRASOUND ABLATION IN THE MANAGEMENT OF SYMPTOMATIC ADENOMYOSIS: ASSESSMENT OF CLINICAL EFFICACY, SAFETY, AND IMPACT ON FERTILITY. A CASE SERIES These remain relatively new, and long-term data on effectiveness and fertility outcomes after such procedures are still accumulating.
The broader picture is one of a condition that has been historically underdiagnosed and undertreated in younger patients, partly because the diagnostic tools were not available and partly because the default treatment was not compatible with future pregnancies. As non-invasive imaging gets more standardized and uterus-preserving treatments improve, the clinical approach to adenomyosis is likely to keep evolving.