August 15, 2023
4 Minutes

Understanding Endometriosis

Understanding Endometriosis
Written by
Dr Zoe Miller
Medical Editor and Doctor at NHS
Amilis makes fertility digestible, accessible, and affordable to help you take charge of your reproductive health and live on your own timeline.

In an eggshell...

  • Symptoms can vary from person to person, the most common one being intense period pains
  • This condition affects around 10% of women of reproductive age.

Endometriosis is a condition where the tissue that lines the uterus grows outside of it. As you can imagine, this may well be painful!

Sadly, this condition affects around 10% of women of reproductive age.1


Endometriosis symptoms can vary from person to person.

This is partly because all women are different. But, also, because the location where the tissue grows outside the uterus affects which symptoms you experience.

Some women may experience severe pain, while others may have no symptoms at all.

The most common symptoms include2:

  • Painful periods
  • Pain during sex
  • Painful bowel movements/urination
  • Chronic/ongoing pelvic pain
  • Tiredness
  • Mood changes
  • Issues with fertility

Find out more about symptoms and living with endometriosis in our other blog.

The Causes

The exact cause of endometriosis is unknown. However, there are several theories.2

Backwards Menstruation

This theory is that menstrual blood containing cells from the uterus flows back through the fallopian tubes and into the pelvis. Here, it implants and grows.

Changes In Cell Type

Known officially as “cellular metaplasia”, one type of cell is able to turn into another.
This can be a part of normal development, or part of a disease.

In endometriosis, it’s thought cells outside the uterus change into uterus cells.

Stem Cells

Stem cells can turn into any cell. Collections of them exist in the body to make repairs and replacements.

One theory suggests stem cells are transported around the body in the blood and turn into cells from the uterus at some point along the way. This leads to endometriosis.

Researchers are still trying to confirm the true cause. Or even causes.

Risk Factors

We might not know exactly what causes it, but there are some things we know that increase your chance of developing endometriosis, such as:

  • Never giving birth
  • Having a period more often than every 28 days
  • Heavy and prolonged periods that last longer than seven days
  • High levels of oestrogen in your body
  • Having a low body mass index
  • Having a structural issue with the vagina, cervix, or uterus that prevents menstruation
  • A family history of endometriosis


Endometriosis can be difficult to diagnose, as the symptoms are similar to other conditions.
A doctor may perform a pelvic exam (with a speculum), ultrasound scan, or MRI scan to check for signs of endometriosis.

In some cases, a laparoscopy may be necessary to confirm the diagnosis. This is a surgery where a small camera is inserted into your abdomen to look for the cause of your symptoms. Samples may be taken to confirm it is definitely endometriosis.

It's important to speak to your GP if you think you may have endometriosis, as it can take a long time to get the right diagnosis. In the UK, an average of eight years.3


Whilst there is no cure for endometriosis, several treatment options are available. Treatments are mainly focused on managing your symptoms.

Pain medication, hormone therapy, and surgery are all possibilities. Surgery is usually not the first choice but may be necessary to remove the endometriosis tissue or, in extreme cases, the uterus and ovaries.2

Endometriosis and Fertility

Many women with endometriosis don’t struggle to get pregnant or have children.

However, endometriosis can affect fertility by causing scar tissue to form. This can make it difficult for the egg to travel to and along the Fallopian tubes, affect egg quality, and disrupt the lining of the uterus, making it difficult for the egg to implant.

Evidence on the best fertility treatment varies. IVF with embryo transfer can be effective if fertility issues continue4, surgery is another option, and some women opt for egg freezing to preserve their fertility.


In conclusion, endometriosis is a common condition that affects many women. Pain, discomfort, and infertility are all symptoms, but there are treatment options available. If you think you may have endometriosis, talk to your doctor as soon as possible.

Written by
Dr Zoe Miller
Medical Editor and Doctor at NHS