For educational purposes only.

What is endometriosis?

Endometriosis is a chronic condition that affects a woman’s reproductive organs. It happens when the lining cells (called the endometrium) of the uterus grow outside of it (see diagram). Often it is found on and around the pelvic and abdominal organs, including the ovaries. Rarely, the endometrial tissue is found in other parts of the body.

About 10% of women of between the ages of 15-49 are affected – around 176 million women worldwide.

What causes endometriosis?

We don’t really know what causes endometriosis, and possible causes or factors may be different from person to person. 

  • Family history: women who have a close relative with the condition are up to 7-10 times more likely to get endometriosis. Also, it is common with twins that both may get endometriosis, particularly if they are identical twins.[1][2]
  • Retrograde (backwards) menstruation: When a woman has a period, the blood flows out of the vagina, but also backwards along the fallopian tubes into the pelvis. In most women (90%) the blood, which will contain endometrial tissue, just gets absorbed or broken down and causes no symptoms; however, in women with endometriosis this endometrial tissue starts to grow.

Other possible factors that may have a role in causing endometriosis are:

  • delay in childbirth
  • heavy bleeding during periods and periods lasting longer than five days
  • first period before 11 years of age
  • regularly having less than 27 days between periods
  • changes in the immune cells (this possibly cause needs further research and understanding)
  • early pregnancy
  • low body weight
  • alcohol use

What happens?

The endometrial tissue cells:

  • are found on organs in the pelvis
  • may start to grow and form patches or nodules on pelvic organs or on the peritoneum (inside lining of the abdomen and pelvis) (see image)
  • have the same cyclical/menstrual changes outside the uterus as inside the uterus
  • may bleed at the same time as your period (menstruation)

Factors that may lower the risk of getting endometriosis are:

  • how many children you have – the chance of getting endometriosis may lower with each pregnancy (this may be related to the hormone progesterone during pregnancy)
  • younger age of first pregnancy
  • the longer time spent breast feeding the less risk
  • regular exercise of more than 4 hours per week 

How do you know if you have endometriosis?

The symptoms are different from woman to woman. Some women have many symptoms where severe pain/s occur, whereas others have no symptoms. About 1/3 of women with endometriosis discover they have it because they have not been able to become pregnant, or because endometriosis is found during an operation for another reason.

The type of symptoms you have and their severity are likely to be related to the location of the misplaced tissue rather than how much misplaced tissue there is.

Approximately 3/4 of women with endometriosis have pelvic pain and/or painful periods.

In the early stages of the disease one or two mild symptoms may be felt for the first day or two of a period. Later, as the condition continues, symptoms may get worse for more days of the month.

In women over the age of 25, endometriosis can make it difficult to get pregnant. This may be because the endometrial cells release chemicals that:

  • interfere with the ability to get pregnant
  • affect the development of the embryo in its early stages

In moderate to severe cases, the scarring caused by the endometrial cells may interfere with the release of an egg (ovulation) or because of damage or blockage. The damage can also prevent the journey of an egg along the fallopian tube and/or the sperm from reaching the egg causing problems with fertility

Symptoms you may experience


Pain is a key symptom of this condition and is not related to how severe the disease is, but to the location of endometrial tissue.


·       Pain immediately before and during your period

·       Pain during or after sex

·       Abdominal, back and/or pelvic pain

·       Pain on going to the toilet or passing wind

·       Ovulation pain, including pain in your thigh or leg (this can also happen normally in some women)


·       Heavy bleeding, with or without clots

·       Irregular bleeding, with or without a regular cycle

·       Bleeding longer than normal

·       Bleeding before your period is due


As the muscle walls of the vagina close tightly or spasm in response to attempted insertion, for example, with a tampon or penis. This can be mildly uncomfortable or it may cause searing or tearing pain.

Bladder & bowel problems

·       Bleeding from your bladder or bowel

·       Change in pattern of bowel habit e.g. constipation, diarrhoea

·       The need to urinate more frequently or some other change from your normal habit


Increase in your abdominal area, with or without pain at the time of your period.


Tiredness or lack of energy, especially around the time of your period.

Mood changes

Anxiety and depression due to ongoing pain.

Reduced quality of life

Taking days off work, study or school because you can’t function normally.

Symptoms during pregnancy

Symptoms of endometriosis appear to go away with pregnancy. This is thought to be because pregnancy hormones cause the endometriosis to reduce. After the baby is born the effects of endometriosis are unclear. In a small study of 23 women[3], the endometrial lesions got worse in the first three months and then got better as the pregnancy continued.

Symptoms during menopause

Usually, endometriosis does go away after menopause. However, it may come back if you start hormone replacement therapy (HRT), but this is rare. Even more rarely, it can return for no reason.

For more information please call 07 32045877.