Adenomyosis is a condition in which endometrial-type tissue grows inside the muscular wall of the uterus, producing heavy bleeding and deep cramping together rather than one or the other. Fishtown Medicine evaluates it with a menstrual history, a pelvic exam, and a transvaginal ultrasound read against the MUSA criteria, then treats symptoms medically and coordinates surgical referral when that becomes the question.
TL;DR: Adenomyosis happens when tissue like the lining of the uterus grows down inside the muscle wall of the uterus. Every month that muscle bleeds and squeezes harder, so periods turn heavy and painful at the same time. For most of the history of this diagnosis, doctors could only be sure after the uterus was removed, which is a big part of why it gets missed. Today a careful pelvic ultrasound can usually see the signs, and an MRI can too. Write down what your period does: how often you change a pad or tampon, how big the clots are, how many days it lasts, and whether you wear 2 products at once. Bring that list, ask for an iron check and a pelvic ultrasound, and start with medicine that lightens the bleeding and calms the cramping. Surgery comes later, if it is needed at all.
If your period has been heavy and painful for years, you have probably already had the visit where someone asked how bad it was, you said bad, and the conversation moved on. Maybe an ultrasound came back with a line about a bulky uterus that nobody explained. Maybe you were handed a birth control pill and told this is how some women are built.
There is a condition that produces both halves of that picture at once. Adenomyosis puts endometrial-type tissue inside the muscle wall of the uterus, so the heavy bleeding and the deep cramping arrive together instead of separately. It is common, it is underdiagnosed, and it gets confused with endometriosis and fibroids often enough that the confusion is part of the story.
What I want you to know is what adenomyosis is, what a scan can and cannot tell you about it, how it differs from the 2 conditions it gets mistaken for, and what changes once somebody names it.
What is adenomyosis?
Adenomyosis is a condition in which endometrial-type tissue, the same kind of tissue that lines the inside of the uterus, is found inside the myometrium, which is the thick muscular wall of the uterus. That tissue answers to the same hormone signals as the lining does. It thickens across the cycle and it bleeds. But it is buried in muscle with nowhere to drain, so the muscle around it becomes inflamed and swollen and thickens over time.
Adenomyosis comes in 2 patterns. Diffuse adenomyosis is spread through the wall, and the uterus tends to enlarge evenly into a rounder, more globe-like shape. Focal adenomyosis sits in a discrete area and can form a mass called an adenomyoma, which is easy to mistake for a fibroid on a quick scan and even during surgery.
How common it is depends on how you look for it, and the honest answer is that nobody has a firm number. Series based on hysterectomy specimens have reported a prevalence anywhere from roughly 9% to 62%, because pathology labs have never agreed on how deep the tissue must sit to count. Imaging-based estimates in gynecology populations run in the range of 12% to 34%. A 2025 systematic review pooling 127 studies put general-population prevalence at about 1% while finding roughly 31% among women being evaluated for infertility. Those numbers are not measuring the same thing, and any page that gives you a single confident figure is smoothing over a gap in what medicine knows.
Why does adenomyosis make periods heavy and painful at the same time?
The anatomy explains the pairing. Most conditions that cause heavy bleeding do it by changing the lining or the cavity, and most conditions that cause severe cramping do it by irritating tissue outside the uterus. Adenomyosis does both from inside the muscle itself.
The bleeding side comes from an enlarged uterus with more endometrial surface to shed, a myometrium threaded with extra blood vessels, and muscle that has lost the ability to contract in a coordinated way. A healthy uterus clamps down at the end of a period and squeezes its own vessels closed. Muscle that is inflamed and interrupted by ectopic tissue does that job poorly, so bleeding runs longer and heavier.
The pain side comes from the same tissue. Blood and inflammatory signaling inside a muscle wall that cannot drain produces the deep, dragging, pressure-type cramping that patients describe as different from ordinary period pain. It often starts a day or 2 before bleeding, peaks with the flow, and gets worse year over year rather than staying level. Heavy menstrual bleeding and painful periods are the 2 symptoms most consistently reported in adenomyosis, and about 1 in 3 people who have it report no symptoms at all.
Why does adenomyosis get missed for so long?
Because everything that would catch it takes time that a 12-minute visit does not have, and because the classic teaching pointed clinicians at the wrong patient.
The exam finding is a diffusely enlarged, globular, tender uterus that feels boggy or soft on a bimanual exam. That is a specific thing to feel for, and a clinician who is not thinking about adenomyosis will read the same exam as normal. Plenty of people with adenomyosis do have a normal exam, so a reassuring exam settles nothing.
The old teaching held that adenomyosis was a disease of women over 40 who had given birth several times, confirmed by a pathologist after hysterectomy. Transvaginal ultrasound and MRI changed that. The condition is now recognized in women in their 20s and 30s with painful periods, pain with sex, abnormal bleeding, and infertility. The teaching lagged the imaging by a couple of decades, and a lot of practicing clinicians learned the older version.
Then there is the company it keeps. Adenomyosis frequently coexists with endometriosis and with fibroids. When a scan finds a fibroid, the search tends to stop there, and a woman leaves with an explanation that accounts for maybe half of her symptoms.
Can a transvaginal ultrasound diagnose adenomyosis?
Yes, a transvaginal ultrasound can support a working diagnosis of adenomyosis, and that is a change from how this was taught 15 years ago. Two consensus efforts made it possible. The MUSA group (Morphological Uterus Sonographic Assessment) first standardized the vocabulary for describing the myometrium, and a 2022 revision by Harmsen and colleagues in Ultrasound in Obstetrics and Gynecology sorted the adenomyosis findings into direct and indirect features.
Direct features point at endometrial-type tissue sitting inside the muscle. There are 3:
- Myometrial cysts, small fluid pockets within the muscle wall
- Hyperechogenic islands, bright patches of tissue inside the muscle
- Echogenic subendometrial lines and buds, bright lines and small projections extending from the lining down into the muscle
Indirect features describe what the muscle does in response, and there are 6:
- Globular uterus, a uterus that has enlarged into a rounder shape
- Asymmetrical myometrial thickening, one wall visibly thicker than the other
- Fan-shaped shadowing, striped shadows radiating out from the affected area
- Translesional vascularity, blood vessels running straight through the area rather than around it
- Irregular junctional zone, an uneven border between the lining and the muscle
- Interrupted junctional zone, a stretch of that border the sonographer cannot see at all
The rule that matters for your report: at least 1 direct feature is required. Indirect features alone, however many of them are listed, do not make the diagnosis. This is the single most useful sentence to carry into a conversation about your own scan, because indirect features are the ones a general ultrasound is most likely to mention in passing.
The accuracy numbers are reasonable and imperfect. In a meta-analysis by Andres and colleagues, 2D transvaginal ultrasound had a pooled sensitivity of 83.8% with a specificity of 63.9%, and 3D imaging ran 88.9% and 56.0%. An earlier systematic review by Champaneria and colleagues found transvaginal ultrasound at 72% sensitivity and 81% specificity, against MRI at 77% and 89%. Read together: ultrasound is good at catching it and less reliable at ruling it in, and MRI is the more specific test when the answer needs to be firmer.
On MRI, the most widely used measure is the junctional zone, the inner layer of muscle just under the lining. A junctional zone thicker than 12 mm is the common threshold, under 8 mm argues against the diagnosis, and the range in between calls for supporting findings such as a junctional-zone-to-myometrium ratio above 40%. Those cutoffs are debated in the literature rather than settled, and MRI costs more and takes longer, so it earns its place when ultrasound is equivocal, when surgery is being planned, or when deep endometriosis is also in question. Our page on abdominal and pelvic imaging covers how we choose between the 2 studies.
The messy prevalence numbers above trace straight back to how this diagnosis used to be made. For most of the time adenomyosis has had a name, the only way to be certain was to examine a uterus that had already been removed, and pathologists never agreed on the criteria for that either. So the evidence base was built almost exclusively on women sick enough to have surgery. The imaging criteria are recent, they are not yet used everywhere, and the person holding the probe has to be looking for these features and reporting them by name.
What does "bulky uterus" on my report mean?
"Bulky uterus" describes size rather than cause. It tells you the uterus measured larger than the sonographer expected on that day, and it stops there. The term is not one of the 9 standardized MUSA features, it has no agreed measurement behind it, and it appears on reports from many different scanners and readers who mean slightly different things by it.
A larger uterus can come from fibroids, from adenomyosis, from previous pregnancies, or from ordinary variation between bodies. Read on its own, the phrase should prompt a better question rather than a conclusion in either direction. The useful follow-up is whether the report describes the junctional zone, whether any direct feature was seen, and whether the uterus was described as globular.
If your report says bulky and nothing else, that is a reason to ask for the scan to be repeated or reviewed with adenomyosis as the specific question. A targeted ultrasound ordered by someone who names what they are looking for is a different study from a routine pelvic scan, even when the machine is identical.
How is adenomyosis different from endometriosis and fibroids?
All 3 conditions can cause painful, heavy periods, and they overlap often enough that finding one is no reason to stop looking for the others. What separates them is where the tissue is and what pattern the symptoms follow.
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| Adenomyosis | Endometriosis | Fibroids | |
|---|---|---|---|
| Where the tissue is | Endometrial-type tissue inside the muscle wall of the uterus | Endometrial-like tissue outside the uterus, on the peritoneum, ovaries, or deep pelvic structures | Noncancerous growths of uterine smooth muscle |
| Typical pain | Deep, dragging cramping tied tightly to the period, worsening year over year | Pain that extends well outside the bleeding window: pain with sex, with bowel movements, with urination, and between periods | Often painless; pressure, fullness, or urinary frequency when large |
| Typical bleeding | Heavy and prolonged, with clots | Variable, and often lighter than the pain would predict | Heavy when the fibroid distorts the cavity |
| Exam | Diffusely enlarged, globular, tender, boggy uterus | Often normal; sometimes tenderness or nodularity behind the uterus | Firm, irregular, lumpy uterus |
| Imaging | Direct MUSA features on transvaginal ultrasound; junctional zone changes on MRI | Ovarian endometriomas and deep disease visible; superficial disease often invisible | Well-defined discrete masses, mapped by FIGO location |
Two distinctions do most of the work in a visit. With endometriosis, the pain refuses to stay inside the period, which is why pain with sex, painful bowel movements, and pain on days when there is no bleeding all point that direction. Our endometriosis guide goes through that picture properly.
With fibroids, location matters far more than size. A submucosal fibroid pressing into the cavity (FIGO type 0, 1, or 2) can cause bleeding badly out of proportion to its measurement, while a much larger fibroid growing outward from the surface may cause pressure with a period that stays manageable. A report listing a 6 cm fibroid tells you very little until you know where it sits.
What else makes periods heavy and painful?
A few causes belong in every workup for this combination, and they are cheap to check.
Bleeding disorders are the ones most often missed. Von Willebrand disease is found in a meaningful share of women evaluated for heavy menstrual bleeding, far above its prevalence in the general population, and ACOG has recommended for years that inherited bleeding disorders be considered in any patient being evaluated for heavy periods, at any age. The clues are historical rather than gynecologic: bleeding that has been heavy since the very first period, a family member with the same story, easy bruising, frequent nosebleeds, and prolonged bleeding after dental work or childbirth.
Thyroid disease and iron deficiency are inexpensive to test and are frequently the reason a person feels as terrible as she does. Heavy periods are a leading cause of iron loss in women of reproductive age, and iron stores run down long before a blood count turns abnormal, so a normal hemoglobin settles nothing about iron. Our guide to heavy periods and anemia covers the iron panel, the bleeding disorder screen, and the non-hormonal options in depth.
Polyps and endometrial overgrowth round out the list, along with pregnancy-related bleeding, which always gets excluded first.
What treatment helps adenomyosis when the goal is symptom control?
Fishtown Medicine is a primary care practice, so the work here is evaluating the cause, treating symptoms medically, ordering and interpreting imaging, correcting iron, and coordinating with gynecology when a procedure becomes the question. Ablation, excision, uterine artery embolization, and hysterectomy are handled by the surgical and interventional teams we refer to.
The Society of Obstetricians and Gynaecologists of Canada guideline on adenomyosis lays out the medical menu: NSAIDs, tranexamic acid, combined oral contraceptives, the levonorgestrel intrauterine system, dienogest and other progestins, and gonadotropin-releasing hormone analogues. Which one comes first depends on whether bleeding or pain is the bigger problem for you, and on whether pregnancy is in the plan.
The levonorgestrel IUD deserves a careful answer, because the confidence around it outruns the trial data. NICE names the levonorgestrel intrauterine system as a first-line treatment for heavy menstrual bleeding in women with suspected or diagnosed adenomyosis, and it is the best-studied medical option in this condition. A 2022 meta-analysis of randomized trials found it reduced period pain scores compared with systemic medication at 3, 6, 9, and 12 months, with better control of bleeding. But a 2025 systematic review and meta-analysis of 28 studies, looking at adenomyosis specifically, concluded there was no clear evidence to recommend it as a single therapy for improving pain and quality of life within 12 months. What performed better was combination: the device placed after a course of a GnRH agonist, or after a procedure. That review also found combination approaches reduced device expulsion, which is more common in an enlarged uterus.
The honest read is that the levonorgestrel IUD is a reasonable first medical step with meaningful support behind it, that much of the literature is small and unblinded, and that it is not guaranteed to work, particularly in a large uterus. Some of these devices carry this use off-label. Going in with that framing is better than being told it will fix everything and then discovering otherwise 6 months later.
Pain control here runs through NSAIDs started before the bleeding begins, hormonal suppression of the cycle, heat, and pelvic floor physical therapy where the muscles have tightened around years of pain. Fishtown Medicine does not prescribe opioids for any condition, and adenomyosis pain responds to controlling the cycle rather than to sedating the pain.
If the bleeding has been heavy for years, correcting iron runs alongside everything else rather than waiting until the bleeding is under control. Feeling human again often arrives from the iron before it arrives from anything else.
How does Fishtown Medicine approach adenomyosis?
The first visit is long enough to get a proper menstrual history and do the exam, which is where most of the diagnosis lives. That means the pattern across years rather than this month, the position of the pain relative to the bleeding, what happened after any pregnancies, what birth control did and did not change, and a bimanual exam looking specifically for a globular, tender, enlarged uterus.
Imaging goes out with the question written on it. A transvaginal ultrasound ordered with "evaluate for adenomyosis, please report MUSA features and junctional zone" produces a different report than a routine pelvic scan, and Philadelphia has plenty of imaging centers capable of that read when the order asks for it. Pelvic MRI comes next when the ultrasound is equivocal or when a surgical conversation is approaching.
Labs run in parallel: a full iron panel rather than a blood count alone, thyroid function, and a bleeding disorder screen when the history points that way. Then we build the symptom plan, review it after a cycle or 2 by text rather than at a visit 3 months out, and bring in gynecology when a procedure becomes the right conversation. If you are in Philadelphia and this pattern is yours, tell Dr. Ash what your cycles have been doing.
Guidance from the Clinic
Actionable Steps in Philly
What to do this cycle if heavy and painful periods are your pattern.
- Track 2 cycles and record numbers rather than adjectives. Note how many hours a pad or tampon lasts on your worst day, the size of the largest clot, the total days of bleeding, whether you wear 2 products at once, and whether you get up at night to change. Any of these counts as heavy: soaking a pad or tampon every hour for several hours in a row, clots the size of a quarter or bigger, bleeding 7 days or longer, needing double protection, or changing overnight.
- Map the pain against the bleeding. Note the day pain starts relative to day 1 of flow, and whether you also have pain with sex, with bowel movements, or on days with no bleeding at all. That pattern is what separates adenomyosis from endometriosis before any scan happens.
- Write down the history nobody asks for. Whether periods have been heavy since the very first one, whether a mother or sister has the same story, whether you bruise easily or bled a long time after a dental procedure. Those answers point at a bleeding disorder.
- Ask for the specific imaging order. Request a transvaginal ultrasound that names adenomyosis as the question and asks for MUSA features and the junctional zone to be described. If a prior report only said "bulky uterus," bring it and ask what the junctional zone looked like.
- Ask for a full iron panel rather than a blood count alone. Ferritin, iron, transferrin saturation, and total iron-binding capacity alongside the complete blood count (CBC). Details on why the CBC alone misses early iron loss are in our guide to heavy periods and anemia.
- Bring all 5 of the above to one visit. This workup fits in a single appointment when the history is already written down, and it usually answers the question within 2 weeks.
Key Takeaways
- Adenomyosis is endometrial-type tissue inside the muscle wall of the uterus, which is why it produces heavy bleeding and deep cramping together rather than one or the other.
- The classic exam finding is a diffusely enlarged, globular, tender, boggy uterus, though many people with adenomyosis have a normal exam.
- Transvaginal ultrasound can now support the diagnosis using the revised 2022 MUSA criteria, and at least 1 direct feature (myometrial cysts, hyperechogenic islands, or echogenic subendometrial lines and buds) is required.
- Indirect features alone, including a globular uterus or an irregular junctional zone, do not establish the diagnosis.
- "Bulky uterus" on a report describes size rather than cause and is not a MUSA feature; ask about the junctional zone and whether any direct feature was seen.
- Prevalence estimates range from about 1% in general-population data to 9% to 62% in hysterectomy series, because the diagnostic criteria themselves have never been standardized across settings.
- Adenomyosis coexists frequently with endometriosis and fibroids, so finding one condition is no reason to stop looking for the others.
- The levonorgestrel IUD is the best-studied medical option and a guideline first-line choice, and the trial evidence for it as a standalone therapy in adenomyosis is weaker than the confidence around it suggests.
Related at Fishtown Medicine
- Heavy Periods and Anemia - the iron panel, the bleeding disorder screen, and the non-hormonal options for the bleeding itself
- Endometriosis - the condition adenomyosis is most often confused with, and the one it most often accompanies
- Painful periods that everyone told you were normal - how to tell ordinary period pain from the kind with a cause underneath it
- Abdominal and Pelvic Imaging - how we choose between ultrasound, CT, and MRI for pelvic questions
- Women's Preventive Imaging - where pelvic MRI does and does not belong
- Iron, Heavy Periods, and Hair Loss - what chronic iron loss does outside the pelvis
- Perimenopause - why cycles change in the 40s, and how that overlaps with this picture
- PCOS - another hormonally driven condition women wait years to have named
- The Musculoskeletal Syndrome of Menopause - the wider set of changes driven by the estrogen transition
Scientific References
- Harmsen MJ, Van den Bosch T, de Leeuw RA, et al. Consensus on revised definitions of Morphological Uterus Sonographic Assessment (MUSA) features of adenomyosis: results of modified Delphi procedure. Ultrasound in Obstetrics & Gynecology. 2022;60(1):118-131. https://obgyn.onlinelibrary.wiley.com/doi/10.1002/uog.24786
- Van den Bosch T, et al. Sonographic classification and reporting system for diagnosing adenomyosis. Ultrasound in Obstetrics & Gynecology. 2019;53(5):576-582. https://obgyn.onlinelibrary.wiley.com/doi/full/10.1002/uog.19096
- Andres MP, Borrelli GM, Ribeiro J, Baracat EC, Abrão MS, Kho RM. Transvaginal Ultrasound for the Diagnosis of Adenomyosis: Systematic Review and Meta-Analysis. Journal of Minimally Invasive Gynecology. 2018;25(2):257-264. https://pubmed.ncbi.nlm.nih.gov/28864044/
- Champaneria R, Abedin P, Daniels J, Balogun M, Khan KS. Ultrasound scan and magnetic resonance imaging for the diagnosis of adenomyosis: systematic review comparing test accuracy. Acta Obstetricia et Gynecologica Scandinavica. 2010;89(11):1374-1384. https://pubmed.ncbi.nlm.nih.gov/20932128/
- Schrager S, Yogendran L, Marquez CM, Sadowski EA. Adenomyosis: Diagnosis and Management. American Family Physician. 2022;105(1):33-38. https://pubmed.ncbi.nlm.nih.gov/35029928/
- Dason ES, Maxim M, Sanders A, Papillon-Smith J, Ng D, Chan C, Sobel M. Guideline No. 437: Diagnosis and Management of Adenomyosis. Journal of Obstetrics and Gynaecology Canada. 2023;45(6):417-429. https://pubmed.ncbi.nlm.nih.gov/37244746/
- Zhang B, Shi J, Gu Z, et al. The role of different LNG-IUS therapies in the management of adenomyosis: a systematic review and meta-analysis. Reproductive Biology and Endocrinology. 2025;23:23. https://pubmed.ncbi.nlm.nih.gov/39948612/
- National Institute for Health and Care Excellence. Heavy menstrual bleeding: assessment and management. NICE guideline NG88. https://www.nice.org.uk/guidance/ng88/chapter/recommendations
- Global prevalence of adenomyosis and endometriosis: a systematic review and meta-analysis. Reproductive Biology and Endocrinology. 2025. https://pubmed.ncbi.nlm.nih.gov/41257733/
- Santulli P, Vannuccini S, Bourdon M, Chapron C, Petraglia F. Adenomyosis: the missed disease. Reproductive BioMedicine Online. 2025. https://www.rbmojournal.com/article/S1472-6483(25)00044-6/fulltext
- American College of Obstetricians and Gynecologists. Committee Opinion No. 580: von Willebrand disease in women. Obstetrics & Gynecology. 2013;122(6):1368-1373. https://pubmed.ncbi.nlm.nih.gov/24264714/
- American College of Obstetricians and Gynecologists. Heavy Menstrual Bleeding (patient FAQ). https://www.acog.org/womens-health/faqs/heavy-menstrual-bleeding
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