There is an association between the presence of endometriosis and subfertility. It is estimated that 30-40% of women with endometriosis may have difficulties in becoming pregnant (but this means that 60-70% will have no problems!). This is two to three times the rate of infertility in the general population. When endometriosis is moderate or severe, it can cause pelvic scarring. The scar tissue formed around endometriosis implants can change the shape or location of the ovaries, fallopian tubes, or uterus. This tissue can block the fallopian tubes, preventing or slowing the movement of eggs from the ovaries to the uterus or surround the ovaries, preventing eggs from moving to the fallopian tubes. The ovaries often contain endometriotic cysts and may become adherent to the uterus, bowel or pelvic side wall.

In some cases, the eggs in the ovaries can be damaged, resulting in decreased ovarian reserve and reduced egg quantity and quality. In this situation, there is likely to be a causal relationship between endometriosis and subfertility. When endometriosis is minimal to mild, a causal relationship is controversial. Endometriosis is more common in subfertile women when compared to the women of proven fertility.

As it is estimated that 30-40% of women with endometriosis may have difficulties in becoming pregnant, that is, unable to conceive after one year of regular intercourse. There is no question that chances for pregnancy in endometriosis are significantly decreased. Without treatment, women with mild endometriosis have an approximately 2% chance for conceiving in any given menstrual cycle (cycle fecundity rate). That chance is less than 1% for women with severe endometriosis. By comparison, age-dependent cycle fecundity (monthly) rates in healthy fertile women range between 15% and 25%.

Laparoscopic surgery can almost double the chance of pregnancy and a live birth for women with mild endometriosis, compared with not having the surgery. Following surgery, rates of pregnancy for women with mild endometriosis as their only fertility problem range from 81% to 84%. Those with moderate or severe endometriosis, including damage to the ovaries, have a 36% to 66% chance of conceiving after surgery. Pregnancy rates are highest within a year of surgery, since endometriosis commonly recurs in spite of the operation.

Pregnancy often causes a remission of endometriosis and therefore their symptoms, as ovulation ceases causing the endometriotic growths to shrink. But it is not always the case as some women report relief from pain during pregnancy, while others report no relief at all. Discomfort during pregnancy is common as a result of the physical changes during pregnancy and this may sometime be confused with endometriotic pain.

Treatment is directed at either relief of pain or infertility. The treatment options for pain range from the analgesics, combined oral contraceptive pill, danazol, oral or depot progesterone injections (medroxyprogesterone acetate) to GnRH agonists. They are equally effective but their side effects and cost profiles differ. Suppression of ovarian function with any of these medications for six months reduces endometriosis-associated pain.     

Surgery may be advisable for some women in whom medical treatment has failed to relieve their pain or infertility. The goal of surgery is to remove or coagulate all visible endometriotic peritoneal lesions, endometriotic ovarian cysts, deep rectovaginal endometriosis and associated adhesions, and to restore normal anatomy. Ablation of endometriotic lesions plus removal of endometriotic adhesions to improve fertility in minimal to mild endometriosis is effective. Pregnancy rates are highest within a year of surgery, since endometriosis commonly recurs in spite of the operation. 

In addition, IUI (intra-uterine insemination) or IVF (in vitro fertilisation) may be required in women who fail to conceive following surgery. Treatment with IUI improves fertility in minimal to mild endometriosis. IVF is an appropriate treatment, especially if tubal function is compromised, if there is also male factor infertility, and/or other treatments have failed. 

Suppression of ovarian function with hormones to improve fertility in endometriosis is not effective and should not be offered for this indication alone. Pregnancy rates are highest within a year of surgery so more harm than good may result from hormonal ovarian suppression treatment, because of adverse effects and the lost opportunity to conceive.

In addition to surgery, IUI or IVF, it is important to maintain a healthy lifestyle prior to embarking on and during the pregnancy. Women should also take folic acid and vitamin supplements, avoid smoking and alcohol, and reduce stress. 

There is no cure for endometriosis, but there is treatment to help women manage and deal with their symptoms. There is also no known prevention at this time. Researchers have not discovered a conclusive reason why women get endometriosis, therefore they do not have a way to prevent it from occurring. 

Radical procedures such as oophorectomy (removal of the ovaries) or total hysterectomy (removal of the womb) are indicated only in severe cases. If a hysterectomy is performed, the cervix should be removed, as persistent pain in a remaining cervix is common due to endometriosis in the cervix. However, it is important to note that women younger than 30 years at the time of hysterectomy for endometriosis-associated pain are more likely than older women to have residual symptoms, to report a sense of loss, and to report more disruption from pain in different aspects of their lives. Although radical resection is an effective treatment for rectovaginal endometriosis, a hysterectomy and/or removal of the ovaries will not guarantee that the endometriosis areas and/or the symptoms of endometriosis will not come back. Currently, there is no known cure for endometriosis, although in some patients, menopause (natural or surgical) will abate the process.  

Several scientific studies suggest that other treatment methods that may be helpful in relieving endometriotic pain include thiamine (vitamin B1), vitamin E, high frequency transcutaneous nerve stimulation, topical heat and herbal remedy toki-shakuyaku-san (tang-gui-shao-yao-san).

Many women with endometriosis report that nutritional and complementary therapies such as vitamin B12, fish oil, magnesium, acupuncture, other herbal remedies and behavioural interventions and spinal manipulation do improve pain symptoms. Whilst there is no evidence from scientific studies in endometriosis to support the use of these treatments, they should not be ruled out if the woman feels that they could be beneficial to her overall pain management and/or quality of life, or work in conjunction with more traditional therapies.

Patient support groups can provide invaluable counselling, support and advice. The website www.endometriosis.org/support.html provides a comprehensive list of support groups.

The treatment options for pain, if you are allergic to painkillers, include the combined oral contraceptive pill, danazol, oral or depot progesterone injections (medroxyprogesterone acetate) and GnRH agonists.   

The cause of endometriosis is still unknown. One theory is that endometriosis is an autoimmune condition (Immune dysfunction - a potential target for treatment in endometriosis by N. Gleicher published in BJOG: An International Journal of Obstetrics and Gynaecology, 1995) and women with endometriosis are more likely than women without the condition to suffer from various autoimmune diseases. Women with one autoimmune condition have a higher risk of also having endometriosis than a woman who does not have autoimmune disease.

Women with endometriosis are also more likely to have abnormally low thyroid function (hypothyroidism), chronic fatigue syndrome, fibromyalgia, lupus, multiple sclerosis, asthma and allergies.