A Resource Guide to Investing in Biotechnology
Directory - Encyclopedia - Stock Index - Pipeline Drugs 

Biotechnology Encyclopedia


Endometriosis is a common medical condition where the tissue lining the uterus (the endometrium, from endo, "inside", and metrium, "mother") is found outside of the uterus, typically affecting other organs in the pelvis. The condition can lead to serious health problems, primarily pain and infertility. Endometriosis primarily develops in women of the reproductive age.


A major symptom of endometriosis is pain, mostly in the lower abdomen, lower back, and pelvic area. The amount of pain a woman feels is not necessarily related to the extent of endometriosis. Some women will have little or no pain despite having extensive endometriosis affecting large areas or endometriosis with scarring. On the other hand, some women, have severe pain even though they have only a few small areas of endometriosis.

Symptoms of endometriosis can include (but are not limited to):

  • Painful, sometimes disabling menstrual cramps (dysmenorrhea); pain may get worse over time (progressive pain)
  • Chronic pain (typically lower back pain and pelvic pain, also abdominal)
  • Painful intercourse (dyspareunia)
  • Painful bowel movements or painful urination (dysuria)
  • Heavy menstrual periods
  • Premenstrual or intermenstrual spotting (bleeding between periods)
  • Infertility

In addition, women who are diagnosed with endometriosis may have gastrointestinal symptoms that may mimick irritable bowel syndrome, as well as fatigue.

Patients who rupture an endometriotic cyst may present with an acute abdomen as a medical emergency.


Endometriosis can affect any woman of reproductive age, from menarche (the first period) to menopause, regardless of her race, ethnicity, whether or not she has children or her socio-economic status. Most patients with endometriosis are in their 20s and 30s. Rarely, endometriosis persists after menopause; sometimes, hormones taken for menopausal symptoms may cause the symptoms of endometriosis to continue.

Current estimates place the number of women with endometriosis between 2 percent and 10 percent of women of reproductive age. About 30 percent to 40 percent of women with endometriosis are infertile. Some women do not find out that they have endometriosis until they have trouble getting pregnant. While the presence of extensive endometriosis distorts pelvic anatomy and thus explains infertility, the relationship between early or mild endometriosis and infertility is less clear. The relationship between endometriosis and infertility is an active area of research.

Anecdotally, endometriosis has been observed in men taking high doses of estrogens for prostate cancer.


Early endometriosis typically occurs on the surfaces of organs in the pelvic and intraabdominal areas. Health care providers may call areas of endometriosis by different names, such as implants, lesions, or nodules. Larger lesions may be seen within the ovaries as endometriomas or chocolate cysts (They are termed cholocate because they contain a thick brownish fluid, mostly old blood). Endometriosis may trigger inflammatory responses leading to scar formation and adhesions

Most endometriosis is found on structures in the pelvic cavity:

Endometriosis may spread to the cervix and vagina or to sites of an surgical abdominal incision. In extremely rare cases, endometriosis areas can grow in the lungs or other parts of the body.

Surgically endometriosis can be staged I-IV ( Revised Classification of the American Society of Reproductive Medicine)


While the exact cause of endometriosis remains unknown, many theories have been presented to explain its development. These concepts do not necessarily exclude each other.

  1. Endometriosis is an estrogen-dependent condition, as it is seen during the reproducive years and generally disappears after menopause. In experimental models, estrogen is necessary to induce or maintain endometriosis. Medical therapy is often aimed at lowering estrogen levels to control the disease.
  2. "Retrograde menstruation", by which some of the menstrual debris of her period flows into her pelvis, may play an important role (Sampson's theory). While most women may have some retrograde menstrual flow, typically their immune system is able to clear the debris and prevents implantation and growth of cells from this occurence. However, in some patients, endometrial tissue transplanted by retrograde menstruation is able to implant and establish itself as endometriosis. Factors that might cause the tissue to grow in some women, but not in others, need to be elucidated, and some of the possible causes below may provide some explanation, i.e. hereditary factors, toxins, or a compromised immune system. It can be argued that the uninterrupted occurence of regular menstruation over decades month after month is a modern phenomenon, as in the past women had more frequently menstrual rest due to pregnancy or lacation.
  3. A competing theory suggests that endometriosis does not represent transplanted endometrium but starts de novo from local stem cells. This process has been referred to as coelomic metaplasia. Triggers of various kind (including menses, toxins, or immune factors) may be necessary to start this process.
  4. Hereditary factors play a role. It is well recognized that daughters or sisters of patients with endometriosis are at higher risk to develop endometriosis themselves. A specific gene, however, has not been identified.
  5. It is accepted that in specific patients endometriosis can spread directly. Thus endometriosis has been found in abdominal incisional scars after surgery for endometriosis.
  6. On rare occasions endometriosis may be transplanted by blood or by the lymphatic system into peripheral organs (i.e. lungs, brain).
  7. Recent research is focussing on the immune system that may not be able to cope with the cyclic onslaught of retrograde menstrual fluid. In this context there is interest to study relationship to autoimmune disease, allergy reactions, and the impact of toxins.

Another area of research is the search for endometriosis markers. These markers are substances made by or in response to endometriosis that health care providers can measure in the blood or urine. If markers are found, health care providers could diagnose endometriosis by testing a woman's blood or urine, which might reduce the need for surgery. CA 125 is known to be elevated in many patients with endometriosis, but not specifically indicative of endometriosis.


A histroy and a physical examination can in many patients lead the physician to suspect the diagnosis. Use of imaging tests may identify larger endometriosic areas, such as nodules or endometriotic cysts. The two most common imaging tests are ultrasound and magnetic resonance imaging (MRI).

The most common type of surgery to identify endometriosis is laparoscopy. The diagnosis is based on the characteristic appearance of the disease, if necessary corraborated by a biopsy. Laparoscopy also allows for surgical treatment of endometriosis.

Cause of pain

How endometriosis causes pain is the topic of much research. Because many women with endometriosis feel pain during or related to their periods, and may spill further menstrual flow into the pelvis with each menstruation, some researchers are trying to reduce menstrual events in patients with endometriosis.

Endometriosic tissue reacts to hormonal stimulation and may "bleed" at time of menstruation. It accumulates locally, causes swelling, and triggers inflammatory responses with activation of cytokines. It is thought that this process may lead to pain perception.


Currently, there is no cure for endometriosis although in most patients menopause (natural or surgical) will abate the process. Nevertheless, a hysterectomy or removal of the ovaries will not guarantee that the endometriosis areas and/or the symptoms of endometriosis will not come back. However, endometriosis can be effectively managed in a large majority of patients. Conservative treatments try to address usually pain or infertility issues.

The treatments for endometriosis pain include:

  • NSAIDs and other pain medication: They often work quite well as they not only reduce pain but also menstrual flow. They are commonly used in conjuction with other therapy. For more sever cases narcotic prescription drugs may have to be used.
  • Hormone suppression therapy: This approach tries to reduce or eliminate menstrual flow and estrogen support. Typically, it needs to be done for several months or even years.
    • Progestins: Progesterone counteracts estrogen and inhibts the growth of the endometrium. Such therapy can reduce or eliminate menstruation in a controled and reversible fashion.
    • Continuous birth control pills consists of the use of birth control pill without the use of the placebo pills. This eliminates monthly bleeding episodes.
    • Danocrine is a suppressive steroid with some androgenic activity. It inhibts the growth of endometriosis but its use is limited as it may cause hirsutism.
    • Gonadatropin releasing hormone agonists (GnRH agonists) induce a profound hypoestrogenism by decreasing FSH and LH levels. While quite effective, they induce menopausal symptoms, and over time may lead to osteoporosis. To counteract such side effect some estrogen may have to be given back (add-back therapy).
  • Surgical treatment: Is usually a good choice if endometriosis is extensive, or very painful. Surgical treatments range from minor to major surgical procedures.
    • Laparoscopy is very usefull not only to diagnose endometriosis, but to treat it. With the use of scissors, cautery, laser, hydrodissection, or a sonic scalpel endometriotic tissue can be ablated or removed in an attempt to restore normal anatomy.
    • Laparotomy can be used for more extensive surgery either either in attempt to restore normal anatomy, or at least preserve reproductive potential, or , in severe cases, remove organs such as ovaries, tubes, and/or the uterus (hysterectomy). In extreme cases bowel surgery or surgery on the urinary tract may be necessary. For patients with extreme pain, a presacral neurectomy may be indicated where the nerves to the pelvis are cut.
  • A variety of alternative treatments are being used in patients with endometriosis, including acupuncture.

Patients who are pregnant generally have less pain during pregnancy, and it is not unusual to have less symptoms after a pregnancy.

Infertility treatments

In-vitro fertilization (IVF) procedures are effective in improving fertility in many women with endometriosis. IVF makes it possible to combine sperm and eggs in a laboratory and then place the resulting embryos into the woman's uterus. IVF is one type of assisted reproductive technology that may be an option for women and families affected by infertility related to endometriosis.

Laparoscopy to remove or vaporize the growths in women who have mild or minimal endometriosis is also effective in improving fertility. Some studies show that surgery can double the pregnancy rate.

In patients with small amounts of endometriosis treatment with fertility medication (Clomiphene) may lead to success.

Relation to cancer

Endometriosis is not the same as endometrial cancer. Current research has not demonstrated an association between endometriosis and endometrial, cervical, uterine, or ovarian cancers. In very rare cases ( much less than one percent), endometriosis is seen with endometrioid cancer, but there is no evidence of a causative role between one and the other. Endometriosis of coexists with leiomyoma or adenomyosis.

External Links

Biotech100 Index
What are the Requirements to be listed in the Biotech100 Index?
 Biotech100 list of companies
Pipeline drugs for the Biotech100

Clinical Trials
What is a Clinical Trial?
Phase I ,-- Phase II, -- PhaseIII
What is Randomized Control?
 What is a Double Blind Experiment?
What is the role of the FDA?

Investing in Stocks
Small Cap Stocks
Stocks and Bonds
Biotech100 Index

Sponsored Links

Careers and Employment
Biotechnology and Pharmaceutical
What are the Fastest Growing Careers?

Key Biotech Terms


All text is available under the terms of the GNU Free Documentation License (see Copyrights for details). Disclaimers. Wikipedia is powered by MediaWiki, an open source wiki engine..

Copyright 2005 BIOTECH100.COM. All rights reserved.