What is endometriosis?

Endometriosis is a common condition in which small pieces of the womb lining (the endometrium) are found outside the womb. This could be in the fallopian tubes, ovaries, bladder, bowel, vagina or rectum.

Endometriosis affects around 2 million women in the UK. Most of them are diagnosed between the ages of 25 and 40.
It's a long-term (chronic) condition that causes painful or heavy periods. It often causes pain in the lower abdomen (tummy), pelvis or lower back. It may also lead to lack of energy, depression and fertility problems.

As part of the normal menstrual cycle, the female hormone oestrogen causes the cells lining the uterus to grow and then break down and bleed if an egg is not fertilised.

Endometriosis occurs when cells of the uterus lining that are found outside of the uterus also grow and then break down and bleed. Because they’re not inside the womb, these cells cannot leave the body when a woman menstruates. Instead, this causes internal bleeding, which can lead to the symptoms and effects described below.

What causes endometriosis?

Although extensive research has been done into the reasons for endometriosis, the exact cause of the condition is unknown. Several theories exist as to why some women develop endometriosis:

  • Retrograde menstruation: cells and fluid from the uterus flow backwards through the fallopian tubes into the abdomen instead of leaving the body. It is believed that this occurs in most women, but that most are able to rid their bodies of this material naturally. In women who are unable to do this, endometriosis occurs. Retrograde menstruation is thought to happen either due to hormones or an immune deficiency.
  • Genetics: some researchers believe that the condition may be hereditary, so you have an increased chance of developing endometriosis if there is a history of the condition in your family.
  • Spreading through the bloodstream: some researchers believe that endometriosis is caused by cells lining the uterus that somehow get into the bloodstream or lymphatic system, from where they spread to other parts of the body.

What are the symptoms of endometriosis?

The severity of endometriosis symptoms varies between individuals, and you may feel extreme pain or you may not display any symptoms at all. It’s important to note that the degree of severity of your symptoms doesn’t usually correspond with the amount of affected tissue in your body, but rather depends largely on where in your body the endometriosis is found. In most cases, women with endometriosis experience some degree of pain in the pelvis, lower abdomen or lower back.

Other symptoms can include:

  • Painful or heavy periods
  • Bleeding between periods
  • Discomfort while urinating
  • Pain during sexual intercourse
  • Fatigue
  • Depression
  • Trouble falling pregnant
  • Psychological problems relating to sex and relationships

Other symptoms can also exist depending on where in the body the affected tissue is. If endometrial tissue is in your intestines, for example, you may experience bowel blockage, while if it is in the lungs, you may cough up blood.

How is endometriosis diagnosed?

Currently, the only way to confirm whether you have endometriosis is via an examination known as a gynaecological laparoscopy. During this procedure, a viewing tube with a camera and light on the end, called a laparoscope, is fed into your body. In most cases, this will be into the abdominal area via your navel while you’re under general anaesthetic.

Once the laparoscope is inside you, the image from the camera is transmitted to a video monitor so that your doctor can check for affected tissue. Your doctor may diagnose endometriosis during this procedure, or he or she may take a biopsy of the tissue for further testing and diagnosis in a laboratory.