Adenomyosis and endometriosis. What is the sister disease?

Important note: The content in this article is for educational and informational purposes only. It does not constitute medical advice and should not replace an individual consultation with a gynecologist, endocrinologist, or clinical dietitian, particularly when diagnosing or treating endometriosis, adenomyosis, or other gynecological conditions.

Imagine you've just had a laparoscopy. When you woke up, the surgeon smiled warmly and told you that everything went according to plan, the lesions were precisely removed, and the inside of your abdomen looked as good as possible. You breathe a sigh of relief, looking forward to a new, pain-free life. But a few months pass, and the familiar, paralyzing cramp returns. Or, worse yet, it never really left. Your uterus feels swollen, painful, and heavy during each period, the bleeding is so heavy it practically saps your energy, and you're left alone with a growing sense of helplessness and the question of why the surgery, supposed to be lifesaving, didn't bring the expected results.

One of the most likely, yet still too rarely considered, answers to this question is adenomyosis. For decades, this disease has languished in the shadow of its more famous sister, endometriosis. Only now, thanks to advances in diagnostic imaging, is it slowly making its way into the public consciousness of patients and gynecologists' offices. Understanding the nature of this condition, its differences from endometriosis, and the close interplay between the two is often the first step towards regaining control over one's body.

What exactly is adenomyosis?

To understand adenomyosis, we need to examine the structure of the uterus itself. In a healthy body, the mucous membrane, or endometrium , lines only the internal cavity of the uterus. This tissue, under the influence of hormones, grows monthly in preparation for a possible pregnancy. If pregnancy doesn't occur, it sheds and is excreted as menstrual blood. The problem arises when cells that look deceptively similar to the endometrium, instead of remaining in place, begin to penetrate deeper into the surrounding uterine muscle, or myometrium.

When these stray fragments of tissue become lodged within the strong, dense muscle fibers, they continue to respond to signals sent by the ovaries. During each period, they attempt to bleed, just like the lining inside the uterine cavity. Because blood cannot easily escape, a chronic, smoldering inflammation develops within the muscle structure. Over time, this leads to the formation of fine scars, swelling, and progressive thickening and distortion of the uterine walls. The uterus becomes abnormally enlarged, tender, and loses its natural elasticity. During menstruation, as it attempts to contract under these changed conditions, it generates extreme pain, and the enlarged surface area of ​​bleeding lining drastically increases the heaviness of the period.

Medicine distinguishes two main forms of this disease, which differ in the way the tissue infiltrates the muscle. In the diffuse form, the diseased lesions are evenly distributed throughout the uterine wall, causing the organ to become symmetrically enlarged and heavy. The focal form, on the other hand, is characterized by endometrial tissue forming a single, clearly demarcated cluster within the myometrium. This lesion, called an adenomyoma or adenomyoma, can closely resemble a common fibroid on imaging studies, which can lead to frequent diagnostic errors. This distinction is crucial because it directly influences the subsequent therapeutic steps the doctor may propose.

How does adenomyosis differ from endometriosis?

While both diseases share a common denominator – the presence of endometrial tissue outside its natural location – the devil is in the details, specifically the location and symptoms. In classic endometriosis, lesions develop entirely outside the uterus. Lesions can appear on the peritoneum, ovaries, bladder, intestines, or ligaments supporting the reproductive organs. The disease wreaks havoc on the free space of the pelvis, leading to the formation of painful adhesions that can literally glue adjacent organs together.

Adenomyosis, on the other hand, chooses a centripetal direction. It doesn't leave the uterine boundaries but destroys it from within, carving passages in its own wall. This fundamental difference explains why standard laparoscopy so often proves ineffective in treating adenomyosis. A surgeon looking through an endoscopic camera sees only the external surface of the organs. They can precisely remove all endometriosis foci from the peritoneum or ovaries, but they are unable to see inside the thick muscle of the uterus, which may appear perfectly normal at first glance.

Differences are also evident in how patients describe their daily struggles. While both diseases can cause severe pain, endometriosis manifests itself in a variety of ways, often depending on the location of the lesions—from stabbing pain in the side, to pain during bowel movements, to shooting pains radiating down the legs. In adenomyosis, the pain is typically more central, deep, dull, and crushing, located directly behind the pubic bone. It is accompanied by extremely heavy bleeding with large clots, which can last much longer than a standard menstrual period and quickly lead to severe anemia and chronic fatigue.

Why do both diseases so often go hand in hand?

In the medical world, it's rare to see such a strong connection between two different conditions. Statistics show that the vast majority of women struggling with endometriosis also have some degree of adenomyosis. This high rate of coexistence clearly suggests that we're not dealing with a mere coincidence, but with deep, shared roots.

Both conditions thrive on the same fuel: excess estrogen and chronic systemic inflammation. They are accompanied by similar immune system dysfunction, which is unable to recognize and destroy cells growing in inappropriate locations in time. Strong scientific hypotheses exist indicating that damage to the delicate interface between the endometrium and the uterine muscle—for example, during surgical procedures, curettage, or even strong labor contractions—may facilitate endometrial cells' penetration into the uterine wall, while the same cells in the same patient more easily implant in the peritoneum.

For you, as a patient, this knowledge is of fundamental practical importance. If your doctor focuses solely on removing the peritoneal lesions of endometriosis, ignoring the condition of the uterus itself, your chances of full recovery dramatically decrease. Conversely, treatment aimed solely at suppressing adenomyosis will not provide relief if deep endometrial infiltrates remain active in your pelvis. Only a holistic approach to both of these "sisters" offers the opportunity to develop an effective plan of action.

Modern diagnostic path

For decades, adenomyosis was a ghost disease. The only way to 100% confirm it was to examine the uterus under a microscope after its surgical removal. This meant that young women suffering from severe pain and bleeding were doomed to be told that "it's just their appearance" or that their symptoms were psychological. Today, thankfully, this grim scenario is a thing of the past.

The key to making a diagnosis is modern imaging technology in the hands of a qualified specialist. High-resolution transvaginal ultrasound, performed according to rigorous international diagnostic criteria, allows for the precise detection of subtle changes in muscle structure. An experienced gynecologist will look for characteristic features in the ultrasound, such as asymmetric uterine wall thickness, small fluid-filled cysts hidden within the muscle, or a loss of a clear boundary between the endometrium and the myometrium.

An even more accurate tool is MRI of the pelvis. This test is particularly useful in diagnostically challenging cases where the doctor must distinguish focal adenomyosis from common uterine fibroids or carefully plan surgery. The radiologist assessing the MRI pays particular attention to the so-called transition zone – if its thickness exceeds twelve millimeters, it is extremely strong and reliable evidence of adenomyosis. However, remember that even the best equipment cannot replace human expertise. The test should always be performed by a specialist who knows the specific features of adenomyosis to look for.

When should a red light go off for you?

There are several very specific signals your body sends that should prompt you to start talking to your doctor about adenomyosis. Above all, it's worth being vigilant if pelvic pain persists or quickly returns after laparoscopic removal of endometriosis. Another clear warning is periods that gradually become heavier, longer, and filled with large, dark blood clots, forcing you to completely subordinate your life to your menstrual calendar.

An equally important sign is tenderness of the uterus itself during a routine gynecological examination in the chair – patients with adenomyosis often experience severe discomfort when touched, and the doctor may describe the uterus as "spherical," "swollen," or "spongy." Deep, distending pain during sexual intercourse and lower back pain that doesn't respond to standard painkillers should also raise concerns. None of these symptoms alone determine the diagnosis, but their coexistence is a clear signal that it's time for a more thorough diagnostic evaluation.

Treatment options and directions

Adenomyosis is a chronic condition, which means that currently, medicine doesn't have a single, magic cure that would permanently and completely reverse the changes in the uterine muscle. This doesn't mean, however, that you're helpless. Treatment is always tailored to the individual, taking into account the patient's age, the severity of the symptoms, and her plans for motherhood.

In most cases, treatment begins with pharmacological methods. Their primary goal is to temporarily suppress ovarian hormonal activity and reduce estrogen levels, which stimulate the lesions to grow and bleed. Your doctor may suggest dedicated hormonal therapy, oral progestogens, or a modern intrauterine device (IUD) that releases hormones directly into the uterus, often drastically reducing bleeding and relieving pain.

Surgical treatment for adenomyosis can be challenging due to the diffuse nature of the lesions. In the case of a focal form, when the adenomyoma is clearly visible and demarcated, surgical enucleation with uterine preservation is possible – an extremely important option for women who wish to conceive in the future. Removal of the uterus, or hysterectomy, remains the last resort. It is primarily considered when other methods have failed, pain and bleeding drastically reduce quality of life, and the patient has already made a conscious decision not to have children.

For too many years, adenomyosis was ignored, condemning millions of women to silent, invisible suffering. Today, thanks to growing knowledge and improved diagnostics, you have every right to expect a reliable assessment of your health. If you feel your symptoms go beyond what a diagnosis of endometriosis can explain, don't hesitate to ask your gynecologist directly about the condition of your uterine muscles. Your body deserves to have its voice heard.

Źródła:

• Vannuccini S. et al. Pathogenesis and medical management of adenomyosis: an update. Human Reproduction Update, 2024.
• Donnez J. et al. Adenomyosis: an update on diagnosis and treatment strategies. Fertility and Sterility, 2025.
• Chapron C. et al. Rethinking adenomyosis: a 2025 consensus on integrated clinical management. Human Reproduction, 2025.
• Harada T. et al. Recent advances in understanding the pathogenesis and treatment of adenomyosis. Reproductive Medicine and Biology, 2025.
• Vercellini P. et al. Therapeutic strategies for adenomyosis-associated pain and bleeding: a 2026 clinical update. Journal of Minimally Invasive Gynecology, 2026.