When people talk about endometriosis, it is common to imagine only small foci of tissue similar to the endometrium located outside the uterus. That explanation is useful, but it does not describe everything that can happen around the lesions.
Endometriosis can be associated with persistent inflammation, local bleeding, tissue repair, adhesions and fibrosis. Over time, these processes may change organ mobility and, in some cases, alter anatomy.
This helps explain why a benign disease can cause pain, obstruction, difficulty becoming pregnant and highly complex surgery. Endometriosis is not formed only by the visible lesion; there is also a reaction of the body around it.
What is fibrosis?
Fibrosis is a repair process in which there is excessive production and deposition of extracellular matrix components, including collagen. When the body suffers an injury, healing is expected. The problem appears when this response remains active or becomes excessive, making tissue thicker, stiffer and less elastic.
Fibrosis is not exclusive to endometriosis. It can participate in diseases of the liver, lungs, kidneys, bowel and other organs. In endometriosis, it occurs in the environment of lesions and can contribute to the way the disease changes the pelvis.
Why can endometriosis produce fibrosis?
Endometriosis lesions interact with hormones, immune cells, blood vessels, nerve fibers and nearby tissues. Repeated episodes of inflammation and repair can stimulate fibroblasts, which may become more active cells called myofibroblasts.
Myofibroblasts produce structural components, contract tissue and participate in the fibrotic process. A 2024 systematic review identified fibrosis and myofibroblasts as central elements in the pathophysiology of endometriosis.
This process does not occur in the same way in every woman or every lesion. Type of endometriosis, location, time of evolution and individual response influence the result.
Are inflammation and fibrosis the same thing?
No. The two processes may be related, but they are not equivalent. Inflammation is a biological response involving cells, vessels and chemical mediators. Fibrosis is a structural modification, with increased scar tissue and stiffness.
This difference helps explain why controlling hormonal stimuli and symptoms does not necessarily undo an anatomical change that is already established.
Are fibrosis and adhesions the same thing?
Fibrosis occurs within or around tissue, making it more rigid and thick. An adhesion is an abnormal band or connection between surfaces that should normally slide freely. Both processes can coexist.
How can endometriosis alter pelvic anatomy?
The pelvis is not made of isolated organs. The uterus, ovaries, tubes, bowel, bladder, ureters, vagina, vessels, ligaments and nerves occupy a relatively small space. When deep lesions, fibrosis and adhesions develop, the natural relationship between these structures can change.
- Ovaries may become attached to the uterus or pelvic wall
- The uterus may lose part of its mobility
- The space behind the uterus may become partially or completely closed
- The bowel and vagina may become adherent
- Ureters may be compressed or surrounded by fibrosis
- The bladder may become attached to the uterus
- Fallopian tubes may have impaired mobility
These changes do not occur in every patient. When they do, they help explain why treatment should be planned before surgery.
What does frozen pelvis mean?
Frozen pelvis describes an extensive anatomical change in which organs have important adhesions and little mobility. It means structures that are normally separate and mobile are joined by disease, fibrosis and adhesions.
In these situations, the limits between organs may become difficult to recognize. Surgery requires experience in complex pelvic anatomy and sometimes the participation of professionals from different specialties.
Can fibrosis cause pain?
It can contribute, but endometriosis pain does not have a single origin. Fibrosis can reduce tissue elasticity, change organ mobility and produce traction on nearby structures. It may also coexist with inflammation, adhesions, muscle involvement and nerve fibers.
The amount of fibrosis seen on an exam or during surgery does not directly measure pain intensity. The nervous system, pelvic floor and associated conditions must also be considered.
Can fibrosis affect the bowel or ureters?
In bowel endometriosis, the lesion and fibrotic reaction may affect the rectal or sigmoid wall. As tissue becomes thicker and more rigid, bowel distension may decrease and narrowing may occur in selected cases.
Deep endometriosis can also involve the ureter directly or produce fibrosis around it. Compression may impair urine flow and affect the kidney even with few symptoms, which is why mapping must evaluate organs that may suffer silently.
Can fibrosis interfere with fertility?
It can participate through different mechanisms. Adhesions and anatomical distortion may change the relationship between the ovary and tube, making egg capture more difficult. Tubal changes, endometriomas, age, ovarian reserve and other factors must also be assessed.
Does fibrosis appear on imaging?
Specialized ultrasound and MRI can identify signs related to deep nodules, fibrotic tissue, adhesions and loss of mobility. Ultrasound has the advantage of dynamic assessment, while MRI can characterize low-signal areas associated with fibrotic components and provide a broad view of the pelvis.
No exam can represent the entire microscopic complexity of fibrosis. Its role is to show anatomical changes and help plan management.
Does lesion size show the amount of fibrosis?
Not necessarily. A small lesion may be associated with relevant fibrotic reaction, while a larger lesion may have a different composition. Location, depth, relationship with organs, mobility, obstruction signs and tissue characteristics also matter.
Does hormonal treatment reverse fibrosis?
Hormonal treatments mainly aim to reduce cyclic activity and control symptoms related to endometriosis. They may reduce pain and inflammatory activity in many patients, but there is no evidence that they consistently reverse established anatomical fibrosis.
This does not mean that every patient with fibrosis needs surgery. If there is no relevant functional compromise and symptoms are controlled, follow-up may be appropriate.
When does fibrosis influence the surgical indication?
The decision does not depend only on the existence of fibrotic tissue. It considers what the change is causing or may cause.
- Relevant bowel obstruction or narrowing
- Ureter involvement and kidney risk
- Anatomical distortion associated with important symptoms
- Persistent pain despite clinical treatment
- Infertility in selected contexts
- Masses or lesions that require clarification
- Functional impact on organs
Why can surgery be more complex in fibrotic areas?
Fibrosis can erase the natural planes that separate organs. Tissues that would normally be identified and moved apart may be joined or hardened. This increases the need to recognize anatomy, locate ureters, vessels and nerves, and separate structures without injury.
Complexity does not depend only on nodule size. A small lesion near the ureter may require more care than a larger lesion in an easier area.
Does removing the lesion mean removing all fibrosis?
Not always. The surgeon must balance disease treatment and preservation of important structures. In some regions, trying to remove all altered tissue can increase risks without proportional benefit.
The goal is not to remove the maximum amount of tissue. It is to treat relevant changes safely and preserve function.
Are there antifibrotic medications for endometriosis?
Currently, there is no antifibrotic medication specifically approved to reverse endometriosis-related fibrosis in routine clinical practice. Fibrosis has become an important field of research, including studies on myofibroblast activation, collagen production and the interaction between inflammation and healing.
Preclinical results in cells or animals do not mean that a treatment is already effective and safe for patients. New therapies need clinical studies to assess dose, safety, adverse effects and real benefit.
Why could this be important for the future?
Much of current treatment focuses on hormonal control, symptom relief and surgery when necessary. A therapy that safely acts on fibrosis could one day help prevent structural progression or reduce the complexity of certain cases.
This is a research perspective, not a promise available today.
What does understanding fibrosis change for the patient?
It helps explain why endometriosis should not be evaluated only by counting foci or measuring lesions. Symptoms and anatomy do not always have a direct relationship, mapping must assess organs and mobility, hormonal treatment and surgery have different goals, and preserving organs and function is as important as removing disease.
Conclusion
Endometriosis is not formed only by visible foci. Repeated inflammation, tissue repair, activation of myofibroblasts and collagen deposition can produce fibrosis.
Fibrosis can make tissues stiffer, favor adhesions, reduce organ mobility and contribute to anatomical distortion. Its presence does not automatically determine surgery; the decision depends on symptoms, organ function, progression risks, patient goals and the possibility of safe treatment.
Understanding fibrosis helps us see endometriosis not only as a collection of lesions, but as a disease capable of modifying the environment and anatomy around them.
Frequently asked questions about endometriosis and fibrosis
What is fibrosis in endometriosis?
It is the excessive accumulation of scar-like tissue and components such as collagen within or around lesions, making tissues stiffer and less elastic.
Are fibrosis and adhesions the same thing?
No. Fibrosis changes the structure of a tissue. An adhesion connects surfaces that should normally slide freely. Both processes can coexist.
Can endometriosis change the position of organs?
Yes. Fibrosis and adhesions can reduce mobility and connect the ovaries, uterus, bowel, bladder or other structures, changing pelvic anatomy.
What does frozen pelvis mean?
It is an expression used when extensive disease and adhesions leave pelvic organs strongly attached to each other and with little mobility.
Can fibrosis cause pain?
It can contribute by reducing elasticity, producing traction and coexisting with inflammation and nerve involvement. However, pain intensity does not depend only on the amount of fibrosis.
Does hormonal treatment reverse fibrosis?
Hormones can control symptoms and disease activity, but there is no evidence that they consistently reverse established anatomical fibrosis.
Does every patient with fibrosis need surgery?
No. The indication considers symptoms, organ involvement, risks, fertility, response to treatment and the patient's goals.
Are there antifibrotic medications for endometriosis?
There is still no antifibrotic medication specifically approved for endometriosis in routine practice. Preclinical research and studies are ongoing.
Can fibrosis affect the bowel or ureters?
Yes. In selected cases, it can contribute to bowel narrowing or ureter compression, with possible impact on organ function.