Endometriosis Explained

Are your periods heavy and painful? Do you experience pain outside of your period, during sexual intercourse or when going to the toilet? These symptoms may suggest endometriosis. 1 in 10 women has endometriosis, though due to misdiagnoses and/or underestimation of period pains, the diagnosis could be delayed for up to 8 years. (1)

So what is endometriosis?

A tissue lines your uterus called the endometrium. When the endometrial tissue grows outside its usual place (uterus), this is known as endometriosis. These tissues can grow in organs within the reproductive tract (e.g. Fallopian tubes, ovaries (known as chocolate cysts), in the deeper layer of your uterus). Rarely, they can also be found in the pouch of Douglas (a small pouch found behind your uterus); pelvis; bowel or bladder.

Figure 1: Endometriosis: Visual Explanation

To date, no clear cause has been found. There may be a genetic component; studies have found increased prevalence in those with close relatives of those with endometriosis. (2) There are several theories proposed, which you can read more about here.

Why is endometriosis so painful?

As these endometriomas are made from the same cells of your uterus, they behave and respond in the same way to the changes in hormones during your period, i.e. thicken and shed blood. Therefore, as these cells’ behaviour is foreign to these organs, their cells become irritated and inflamed. Therefore, during your period you may experience:

      • Painful and heavy periods. The pain is usually described as a dull or burning sensation, at the lower part of your belly and pelvis. You may also have pain during deep sexual intercourse. 
      • Pain on passing urine or stool if there are endometriomas (clusters of endometrial cells) in your bladder or bowel. There may also be some blood in your urine or stool as these cells shed. 

Be aware that:

    1. 25% of women may not experience any pain
    2. The severity of pain is not an indication of how severe the condition is
    3. You may also experience chronic pain and bleeding outside of your period
        1. Chronic inflammation can lead to scar tissue, which can stick to other structures, such as your uterus sticking to your bowel (known as adhesions). 
        2. The pain may be felt as a stabbing or pulling (due to the tension). Alongside the pain, you may also feel sick, bloated and constipated.

Why is there a delay in diagnosis?

As endometriosis can present with urinary and bladder problems, doctors may sometimes confuse these symptoms with other conditions, such as irritable bowel syndrome. Also, there may be 2 conditions at once, masking endometriosis. Moreover, as pain is an expected symptom during periods, sometimes doctors may find it difficult to differentiate between what is normal and not normal.

Laparoscopy is the most accurate method to diagnose endometriosis. It is a procedure that involves general anaesthesia, where a small incision is made in your belly to look for endometriomas using a telescope-like instrument. They may also take a sample of the tissue (biopsy) to look under a microscope.

Is my fertility compromised?

Endometriosis can reduce fertility, though there is insufficient evidence explaining why. It may well be due to the inflammation damaging the eggs or tubes – or the pain causing significant stress may send signals to the brain that your body is not ready to have a baby. Nevertheless, 60-70% of women with endometriosis can still get pregnant naturally, regardless of severity. (3) Many women can also successfully conceive with fertility treatment. When pregnant, your pain may disappear, though it is likely to return after birth. However, there is an increased risk of miscarriage (from 20% to 25%), and the risk of the pregnancy being outside the uterus (ectopic pregnancy) is doubled. (3)

How is endometriosis managed?

There is no cure for endometriosis, treatment aims to alleviate symptoms.

      • Pain relief, such as ibuprofen/paracetamol, may be given. If these don’t work, doctors may suggest hormonal treatment, such as contraception, to reduce the hormones oestrogen and progesterone (hormones responsible for the thickening and shedding of endometrial cells).
      • If to no avail, your GP may transfer you to specialised care at the hospital. At the hospital, you may be offered:
          • Medications such as goserelin. They induce a ‘fake’ menopause through reducing oestrogen levels. You may experience menopausal symptoms, such as hot flushes. 
          • Some women who are not planning to have kids and severe pain may be offered a hysterectomy (removal of the uterus), though there is still a risk of recurrence. 
          • If your main concern is infertility, doctors will tailor treatment to prioritise this.
              • You may be offered surgery (laser/excision) to undo some adhesions or remove cysts. This is usually only offered to mild endometriosis (i.e. no involvement of the bladder/bowel), as there is evidence that it increases pregnancy rates. (3)
              • Alternatively, you may be referred quicker for conception through in-vitro fertilisation.

Endometriosis can be a challenging and distressing condition, and its impact should no longer be underestimated. More research and funding is required to unravel the underlying cause, which may help more targeted treatment options. At the time being, it remains a mystery.


  1. Endometriosis in the UK: time for change [Internet]. Available from: https://www.endometriosis-uk.org/sites/endometriosis-uk.org/files/files/Endometriosis%20APPG%20Report%20Oct%202020.pdf
  2. HANSEN KA, EYSTER KM. Genetics and Genomics of Endometriosis. Clinical Obstetrics and Gynecology [Internet]. 2010 Jun;53(2):403–12. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4346178/
  3. Endometriosis, fertility and pregnancy | Endometriosis UK [Internet]. www.endometriosis-uk.org. [cited 2021 Mar 21]. Available from: https://www.endometriosis-uk.org/endometriosis-fertility-and-pregnancy

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