What is endometriosis?
Endometriosis is a disorder in which tissue similar to the tissue that forms the lining of your uterus grows outside of your uterine cavity. The lining of your uterus is called the endometrium.
With endometriosis, the endometrial-like tissue acts as endometrial tissue would — it thickens, breaks down, and bleeds with each menstrual cycle. But because this tissue has no way to exit your body, it becomes trapped. When endometriosis involves the ovaries, cysts called endometriomas may form. Surrounding tissue can become irritated, eventually developing scar tissue and adhesions — bands of fibrous tissue that can cause pelvic tissues and organs to stick to each other.
Endometriosis can cause pain — sometimes severe — especially during menstrual periods. Fertility problems also may develop. Fortunately, effective treatments are available.
Endometriosis occurs when endometrial-like tissue grows on your ovaries, bowel, and the tissues lining your pelvis. It’s unusual for endometrial tissue to spread beyond your pelvic region, but it’s not impossible. The endometrial implant is the tissue growing outside of your uterus that is called endometrial tissue.
The hormonal changes of your menstrual cycle affect the misplaced endometrial tissue, causing the area to become inflamed and painful. This means the tissue will grow, thicken, and break down. Over time, the tissue that has broken down has nowhere to go and becomes trapped in your pelvis.
This tissue trapped in your pelvis can cause:
- scar formation
- adhesions, in which tissue binds your pelvic organs together
- severe pain during your periods
- fertility problems
Endometriosis is a common gynecological condition, affecting up to 10 percent of women. You’re not alone if you have this disorder.
Types of Endometriosis
There are three main types of endometriosis, based on where it is:
- Superficial peritoneal lesion. This is the most common kind. You have lesions on your peritoneum, a thin film that lines your pelvic cavity.
- Endometrioma (ovarian lesion). These dark, fluid-filled cysts, also called chocolate cysts, form deep in your ovaries. They don’t respond well to treatment and can damage healthy tissue.
- Deeply infiltrating endometriosis. This type grows under your peritoneum and can involve the organs near your uterus, such as your bowels or bladder. About 1% to 5% of women with endometriosis have it.
The symptoms of endometriosis vary. Some women experience mild symptoms, but others can have moderate to severe symptoms. The severity of your pain doesn’t indicate the degree or stage of the condition. You may have a mild form of the disease, yet experience agonizing pain. It’s also possible to have a severe form and have very little discomfort.
The primary symptom of endometriosis is pelvic pain, often associated with menstrual periods. Although many experiences cramping during their menstrual periods, those with endometriosis typically describe menstrual pain that’s far worse than usual. Pain also may increase over time.
Common signs and symptoms of endometriosis include:
- Painful periods (dysmenorrhea). Pelvic pain and cramping may begin before and extend several days into a menstrual period. You may also have lower back and abdominal pain.
- Pain with intercourse. Pain during or after sex is common with endometriosis.
- Excessive bleeding. You may experience occasional heavy menstrual periods or bleeding between periods (intermenstrual bleeding).
- Pain with bowel movements or urination. You’re most likely to experience these symptoms during a menstrual period.
- Infertility. Sometimes, endometriosis is first diagnosed in those seeking treatment for infertility.
- Other signs and symptoms. You may experience fatigue, diarrhea, constipation, bloating or nausea, especially during menstrual periods.
The severity of your pain may not be a reliable indicator of the extent of your condition. You could have mild endometriosis with severe pain, or you could have advanced endometriosis with little or no pain.
Endometriosis is sometimes mistaken for other conditions that can cause pelvic pain, such as pelvic inflammatory disease (PID) or ovarian cysts. It may be confused with irritable bowel syndrome (IBS), a condition that causes bouts of diarrhea, constipation, and abdominal cramping. IBS can accompany endometriosis, which can complicate the diagnosis.
When to see a doctor
See your doctor if you have signs and symptoms that may indicate endometriosis.
Endometriosis can be a challenging condition to manage. An early diagnosis, a multidisciplinary medical team and an understanding of your diagnosis may result in better management of your symptoms.
You may also have no symptoms. It’s important that you get regular gynecological exams, which will allow your gynecologist to monitor any changes. This is particularly important if you have two or more symptoms.
What causes endometriosis?
During a regular menstrual cycle, your body sheds the lining of your uterus. This allows menstrual blood to flow from your uterus through the small opening in the cervix and out through your vagina.
The exact cause of endometriosis isn’t known.
One of the oldest theories is that endometriosis occurs due to a process called retrograde menstruation. This happens when menstrual blood flows back through your fallopian tubes into your pelvic cavity instead of leaving your body through the vagina.
Another theory is that hormones transform the cells outside the uterus into cells similar to those lining the inside of the uterus, known as endometrial cells.
Others believe the condition may occur if small areas of your abdomen convert into endometrial tissue. This may happen because the cells in your abdomen grow from embryonic cells, which can change shape and act like endometrial cells.
These displaced endometrial cells may be on your pelvic walls and the surfaces of your pelvic organs, such as your bladder, ovaries, and rectum. They continue to grow, thicken, and bleed over the course of your menstrual cycle in response to the hormones of your cycle.
It’s also possible for the menstrual blood to leak into the pelvic cavity through a surgical scar, such as after a cesarean delivery (also commonly called a C-section).
Another theory is that the endometrial cells are transported out of the uterus through the lymphatic system. Still another theory purports it may be due to a faulty immune system that isn’t destroying errant endometrial cells.
Some believe endometriosis might start in the fetal period with misplaced cell tissue that begins to respond to the hormones of puberty. This is often called Mullerian theory. The development of endometriosis might also be linked to genetics or even environmental toxins.
Several factors place you at greater risk of developing endometriosis, such as:
- Never giving birth
- Starting your period at an early age
- Going through menopause at an older age
- Short menstrual cycles — for instance, less than 27 days
- Heavy menstrual periods that last longer than seven days
- Having higher levels of estrogen in your body or a greater lifetime exposure to estrogen your body produces
- Low body mass index
- One or more relatives (mother, aunt or sister) with endometriosis
- Any medical condition that prevents the passage of blood from the body during menstrual periods
- Disorders of the reproductive tract
Endometriosis usually develops several years after the onset of menstruation (menarche). Signs and symptoms of endometriosis may temporarily improve with pregnancy and may go away completely with menopause unless you’re taking estrogen.
Endometriosis may raise your risk of ovarian cancer or another cancer called endometriosis-associated adenocarcinoma.