Endometriosis

Endometriosis is a condition in which tissue similar to that of the uterus grows elsewhere in the body, most typically in the pelvis, on the ovaries, rectum, sigmoid colon, bladder, distal ureter and the pouch of Douglas (the area between the uterus and the rectum) (National Institute for Health and Care Excellence (NICE), 2020).

The cells that make up this tissue are affected by hormones, in the same way as the tissue that builds up in the womb. The womb lining breaks down and is shed during menstruation, but there is no outlet for the tissue outside of the uterus, so the blood cannot be shed (Endometriosis UK, 2022a).

Around one in 10 people with a uterus of reproductive age are thought to have endometriosis. Among those who are infertile, that figure is as high as 30 to 50%. On average, it takes around 8 years from the onset of

The main symptoms are (NICE, 2017):

• chronic pelvic pain
• dysmenorrhoea (period pain) that affects day-to-day life
• pain during or after sex
• gastrointestinal symptoms related to periods, especially painful bowel movements
• urinary symptoms related to periods, especially pain passing urine or blood in urine
• infertility
• fatigue

Symptoms can be split into four categories (Endometriosis UK, 2022c):

• pain symptoms
  • painful periods
  • pain on ovulation
  • pain during or after sex
  • pelvic pain
  • pain during an internal examination

• bleeding symptoms
  • heavy periods
  • passing clots
  • prolonged bleeding
  • bleeding or spotting in between periods
  • passing dark-coloured blood before a period

• bowel and bladder symptoms
  • painful bowel movements
  • pain during or after passing a stool
  • bleeding from the bowel
  • pain when passing urine
  • irritable bowel syndrome (IBS) symptoms, especially during a period
    • diarrhoea
    • constipation
    • bloating

• other symptoms
  • tiredness and lethargy
  • lack of energy
  • depression
  • back and leg pain

These signs and symptoms can have other causes, so it is important to rule

The exact cause of endometriosis is not known, but there are several possible explanations and combinations of factors that account for why some people develop the condition (Endometriosis UK, 2022d; NICE 2020b).

Retrograde menstruation – this is where cells from the endometrium flow backwards from the womb lining, through the fallopian tubes and attach or implant themselves onto the pelvic organs, where the cells then grow.

It is estimated that around 90% of people who menstruate experience some degree of retrograde menstruation. The proportion who develops endometriosis is comparatively small, and some people develop the disease after hysterectomy. Also, rare cases have been seen in men who have had hormone treatment. So retrograde menstruation is unlikely to be a major cause of endometriosis.

Genetics – several studies have pointed to a genetic predisposition to endometriosis, and some families may be more prone to the disease. However, to date no gene

Patients with suspected endometriosis should keep a diary of symptoms and pain, which will help guide diagnosis and identify patterns (NICE, 2017).

This can also help to indicate or rule out other conditions, like pelvic inflammatory disease, fibroids or irritable bowel syndrome (NICE, 2020). However, it is important to bear in mind that some patients may have mild symptoms, or no symptoms at all. This does not preclude endometriosis.

The first step in diagnosing the disease is an abdominal and pelvic examination if possible. Even if these are normal, patients might need a transvaginal (internal) ultrasound.

If a transvaginal ultrasound is not possible, is inconclusive or suggests endometriosis deep in the ureter, bowel or bladder, the patient should be offered a pelvic MRI scan.

Patients with severe, persistent symptoms or pelvic signs of endometriosis, or when initial treatment and management has not been successful, should be referred to a specialist

Some patients can be managed in primary care with appropriate analgesia and if indicated, hormone treatment. They should be monitored and followed up every 3 to 6 months – sooner if pain persists.

Patients can be offered a short-term trial of pain relief, for example paracetamol or non-steroidal anti-inflammatory drugs (NSAIDs) for a period of 3 months, at which point they should be reviewed.

They might also benefit from hormone therapy; for example, the combined oral contraceptive pill (COP), or a progesterone treatment, such as progesterone-only contraceptive pill, implant, injectable, or intrauterine levonorgestrel.

These treatments can help manage endometriosis-related pain and do not affect fertility. However, they should not be used in patients who are trying to conceive (NICE, 2020d).

Patients should be referred to secondary care if the condition progresses, if they have the disease deep in the bowel, bladder or ureter, or if they have an endometrioma (deep

Endometriosis UK. Endometriosis in the UK: time for change. APPG on Endometriosis Inquiry Report. 2020. www.endometriosis-uk.org/sites/endometriosis-uk.org/files/files/Endometriosis%20APPG%20Report%20Oct%202020.pdf (accessed 22 November 2021)

Endometriosis UK. Understanding endometriosis. 2022a. https://www.endometriosis-uk.org/what-endometriosis (accessed 6 December 2022) 

Endometriosis UK. Endometriosis facts and figures. 2022b. www.endometriosis-uk.org/endometriosis-facts-and-figures (accessed 6 December 2022) 

Endometriosis UK. Endometriosis symptoms. 2022c. https://www.endometriosis-uk.org/symptoms (accessed 6 December 2022) 

Endometriosis UK. Causes of endometriosis. 2022d. www.endometriosis-uk.org/causes-endometriosis (accessed 6 December 2022) 

Endometriosis UK. Surgery and endometriosis. 2022e. www.endometriosis-uk.org/surgery-and-endometriosis (accessed 6 December 2022) 

Mayo Clinic. Gynecological care for trans men. 2019. www.mayoclinic.org/healthy-lifestyle/adult-health/in-depth/gynecological-care-for-trans-men/art-20473719 (accessed 22 November 2021)

National Institute for Health and Care Excellence. Endometriosis: diagnosis and management NICE guideline [NG73]. 2017. www.nice.org.uk/guidance/ng73/chapter/Recommendations#endometriosis-symptoms-and-signs  (accessed 22 November 2021)

National Institute for Health and Care Excellence. Endometriosis: what is it? (CKS). 2020a. www.cks.nice.org.uk/topics/endometriosis/background-information/definition/ (accessed 22 November 2021) 

National Institute for Health and Care Excellence. Endometriosis: What are the causes and risk factors? (CKS). 2020. https://cks.nice.org.uk/topics/endometriosis/background-information/causes-risk-factors/ (accessed 6 December 2022) (NICE 2020b)

National Institute for Health and Care Excellence. Endometriosis: When should I suspect endometriosis? (CKS). 2020c.