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A benign condition in which tissue that looks like endometrial tissue grows in abnormal places in the abdomen.

PubMed Health Glossary
(Source: NIH - National Cancer Institute)

About Endometriosis

Endometriosis is one of the most common medical conditions affecting the lower abdomen (lower belly) in women. In endometriosis, the kind of tissue that normally lines the inside of the womb (endometrial tissue) also grows outside of it. This can happen without the woman being aware of it. But in other women endometriosis is a chronic disease, associated with severe pain and fertility problems.

It often takes years for endometriosis to be diagnosed as the cause of these problems. Until the diagnosis is made, many women try to cope with their pain somehow. They believe that the pain — even really bad pain — is a normal part of their menstrual period.

There is currently no cure for endometriosis. But there are many things that can be done to relieve the symptoms. And if treatment is adapted to suit women's personal circumstances and the severity of their endometriosis, many can cope quite well with the disease.

Like with other chronic conditions, it is important to get to know your own body and how it reacts, in order to find ways to manage the symptoms. Getting hold of good information and consulting experienced, supportive doctors can help... Read more about Endometriosis

What works? Research summarized

Evidence reviews

Accuracy of laparoscopy in the diagnosis of endometriosis: a systematic quantitative review

Bibliographic details: Wykes C B, Clark T J, Khan K S.  Accuracy of laparoscopy in the diagnosis of endometriosis: a systematic quantitative review. BJOG. An International Journal of Obstetrics and Gynaecology 2004; 111(11): 1204-121215521864

Danazol for pelvic pain associated with endometriosis

Danazol reduces the painful symptoms of endometriosis but has androgenic effects. Endometriosis is a painful condition where endometrial tissue grows outside the uterus. It can cause cysts and infertility. Danazol is a hormone that produces male characteristics as well as weight gain and acne. It does, however, relieve the painful symptoms of endometriosis, although the side effects can be unacceptable. The improvement was still present six months after treatment was stopped. There was some evidence that women who took danazol were satisfied with the treatment compared with women who had inactive treatment.

There is no evidence that hormonal suppression either before or after surgery for endometriosis is associated with a benefit

Endometriosis is caused by the lining of the uterus (endometrium) spreading outside the uterus. It can cause pelvic pain, painful periods and infertility. Common treatments are hormonal suppression with medical therapy to reduce the size of endometrial implants or laparoscopic surgery (where small incisions are made in the abdomen) to remove visible areas of endometriosis. There is no evidence that hormonal suppression either before or after surgery is associated with a benefit compared with surgery alone.

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Summaries for consumers

Endometriosis symptoms

Endometriosis causes serious pain and cramps in some women, while others only have a little discomfort or notice nothing at all. Women usually have endometriosis symptoms during their menstrual period, but may also experience them at other times. The severity of symptoms does not always depend on things like the extent of endometrial tissue growth a woman has in her body.Endometriosis is a condition where the kind of tissue that normally lines the womb (endometrial tissue) grows in other parts of a woman’s body too. These “growths” are known as endometrial implants. They do not always cause pain. Endometriosis can lead to various symptoms, depending on things like how many endometrial implants a woman has, and where they are in her body. The most common symptoms are:Very painful menstrual periods (dysmenorrhea): When a woman has her period (menstruation), the muscles in the wall of her womb repeatedly tighten and squeeze in order to shed the lining of the womb. This can cause period pain. Women who have endometriosis may have particularly severe pain and cramping during their period. Many girls and women think this is normal because things have always been that way for them. It never crosses their mind that their severe period pain might be caused by a medical condition like endometriosis.Pain during sex (dyspareunia): This pain is usually described as burning or cramp-like pain. Sometimes women only feel it after they have finished having sex.Abdominal (lower belly) pain: Various degrees of pain may be felt in different parts of the abdomen, sometimes radiating to the back or legs. The pain is not necessarily associated with women’s menstrual period. Permanent (chronic) abdominal pain tends to be rare.Gastrointestinal (stomach and bowel) problems: If endometriosis affects a woman’s bowel, she might feel full or have painful bowel movements. If it affects her bladder, passing urine might hurt.General exhaustion: Severe and frequent endometriosis symptoms often lead to general exhaustion. This makes women less able to cope with physical and mental strain.All of these symptoms can be caused by other things too, so endometriosis cannot be clearly diagnosed based on these symptoms alone.

The causes of endometriosis

In endometriosis, the kind of tissue that lines the womb (endometrial tissue) also grows outside the womb. It is still not clear why this happens. There are various theories about what causes endometriosis. Several factors probably play a role.The inside walls of the womb (uterus) are completely lined with mucous membranes known as the endometrium. These are different to other mucous membranes in the body, particularly in their ability to change: Once a month, during each menstrual cycle, their cells multiply and the lining becomes thicker so that it can nourish a fertilized egg if necessary. If fertilization does not take place and the woman does not become pregnant, most of the thick membrane tissue which has built up is shed and leaves her body during her period. The process of building up and shedding the lining of the womb is regulated by the female sex hormones estrogen and progesterone.Illustration: Womb without endometriosis - as described in the articleEffect of hormones on the lining of the womb (uterus) during a menstrual cycle Illustration: Effect of hormones on the lining of the womb (uterus) during a menstrual cycleIn endometriosis, the kind of tissue that normally lines the womb also grows in other parts of the body. Medically speaking, there are different types of endometriosis, depending on where the endometrial tissue grows.In the muscles of the womb or in the wall of a Fallopian tube, where the tissue is attached to the lining of the womb (common);in the pelvic area, including the ovaries, Fallopian tubes and the “Pouch of Douglas” found between the womb and rectum at the end of the bowel (common);outside the pelvic area, for instance in the bladder or bowel (rare), and very rarely in parts of the body that are further away, like the lungs.Every month during the menstrual cycle, the mucous membrane tissue in endometrial implants outside of the womb is built up and shed. But because the blood and shed tissue cannot leave the woman’s body through her vagina, they stay near the endometrial area. Here they can lead to inflammations, which in turn can cause scars and adhesions to develop.Illustration: Womb with endometrial implants, as decribed in the text

Endometriosis: Surgery: What are the advantages and disadvantages of additional hormone therapy?

There is no proof that taking hormonal medication before or after endometriosis surgery improves the outcome of the treatment. But hormone products such as GnRH analogues do often have side effects and reduce fertility during treatment.

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Terms to know

The layer of tissue that lines the uterus.
Fallopian Tubes
A slender tube through which eggs pass from an ovary to the uterus. In the female reproductive tract, there is one ovary and one fallopian tube on each side of the uterus.
A chemical produced in one part of the body and released into the blood to trigger or regulate particular functions of the body. For example, insulin is a hormone made in the pancreas that tells other cells when to use glucose for energy. Synthetic hormones, made for use as medicines, can be the same or different from those made in the body.
Ovarian Cysts
An ovarian cyst is any collection of fluid, surrounded by a very thin wall, within an ovary. Any ovarian follicle that is larger than about two centimeters is termed an ovarian cyst. The vast majority of ovarian cysts are harmless (benign). Some ovarian cysts cause problems, such as bleeding and pain.
A group of cells that act together to carry out a specific function in the body. Examples include muscle tissue, nervous system tissue (including the brain, spinal cord, and nerves), and connective tissue (including ligaments, tendons, bones, and fat). Organs are made up of tissues.
Uterus (Womb)
The small, hollow, pear-shaped organ in a woman's pelvis. This is the organ in which a fetus develops. Also called womb.

More about Endometriosis

Photo of a young adult woman

Also called: Endo

See Also: Period Pain, Menstruation

Other terms to know: See all 6
Endometrium, Fallopian Tubes, Hormones

Keep up with systematic reviews on Endometriosis:


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