Endometriosis: Symptoms, Causes, Diagnosis & NHS Treatment

Endometriosis is a chronic condition where tissue similar to the lining of the uterus (endometrium) grows outside the uterus — on the ovaries, fallopian tubes, bowel, bladder, and other areas. It affects approximately 1.5 million women and people with a uterus in the UK — roughly 1 in 10 women of reproductive age. Despite its prevalence, women in the UK wait an average of 8 years from first symptoms to diagnosis, a deeply troubling statistic that reflects widespread under-recognition of this condition in primary care.

Symptoms of Endometriosis

Symptoms vary widely — some women have severe pain with minimal disease, while others have extensive endometriosis with few symptoms. Common symptoms include:

  • Pelvic pain — often cyclical (linked to periods) but can be persistent
  • Painful periods (dysmenorrhoea) — severe period pain that disrupts daily life; not just “bad periods”
  • Pain during or after sex (dyspareunia)
  • Pain when urinating or opening bowels — particularly during periods
  • Heavy or irregular periods
  • Fatigue — often severe, especially during periods
  • Bloating — sometimes called “endo belly”
  • Difficulty getting pregnant — endometriosis accounts for 30–50% of cases of female infertility
  • Bowel symptoms — diarrhoea, constipation, bloating around periods (often misdiagnosed as IBS)

Diagnosis: The NHS Pathway

NICE guideline NG73 (2017) recommends that GPs consider endometriosis in any woman presenting with cyclical pelvic pain, painful periods, or painful sex — and refer promptly to a gynaecologist if suspected.

Laparoscopy: The Gold Standard

Endometriosis cannot be definitively diagnosed by symptoms, blood tests, or ultrasound alone. The gold standard is diagnostic laparoscopy — a keyhole surgical procedure under general anaesthetic where a camera is inserted through the abdomen. Ideally, biopsy of suspicious tissue confirms the diagnosis histologically. NICE states that a normal ultrasound does NOT rule out endometriosis.

Imaging

While transvaginal ultrasound cannot detect superficial peritoneal endometriosis, it can identify:

  • Endometriomas (ovarian cysts) — “chocolate cysts” filled with old blood
  • Deep infiltrating endometriosis (DIE) — when performed by a specialist endometriosis sonographer

MRI is used in specialist endometriosis centres for surgical planning when deep infiltrating disease is suspected.

NHS Treatment for Endometriosis

Pain Management

  • NSAIDs (naproxen, ibuprofen) — first-line for period pain; more effective than paracetamol for dysmenorrhoea
  • Hormonal treatments — suppress ovulation and reduce menstrual cycles, reducing endometriosis growth and pain
  • Combined oral contraceptive pill — first-line hormonal option; taken continuously (without pill-free intervals) for maximum effect
  • Progestogen-only options — norethisterone, desogestrel, Mirena IUS (levonorgestrel) — highly effective for pain and bleeding
  • GnRH analogues (goserelin/Zoladex, leuprorelin/Prostap) — create temporary medical menopause; highly effective but require “add-back” HRT to prevent bone loss; used for 6 months at a time
  • Dienogest — a progestogen specifically licensed for endometriosis (Visanne); evidence shows efficacy comparable to GnRH analogues with fewer side effects

Surgery

  • Laparoscopic excision — surgical removal of endometriosis lesions; gold standard surgical treatment; significantly reduces pain and improves fertility
  • Laparoscopic ablation — burning lesions; less effective than excision for deep disease
  • Endometrioma surgery — removal or drainage of ovarian endometriomas (though drainage alone has high recurrence)
  • Hysterectomy — definitive treatment for women who have completed their families; should be combined with removal of endometriosis deposits to maximise pain relief

BSGE Accredited Endometriosis Centres

For complex or deep infiltrating endometriosis, referral to a BSGE (British Society for Gynaecological Endoscopy) accredited specialist endometriosis centre is recommended. These centres have multidisciplinary teams including gynaecologists, colorectal surgeons, urologists, pain specialists, and specialist nurses. You can find your nearest centre at bsge.org.uk.

Endometriosis and Fertility

Endometriosis affects fertility through multiple mechanisms — distorted pelvic anatomy, ovarian damage from endometriomas, inflammatory effects on eggs and embryos, and reduced ovarian reserve. However, many women with endometriosis conceive naturally. For those who struggle:

  • NHS IVF entitlement — women with endometriosis who meet criteria are entitled to NHS-funded IVF under NICE guidelines; access varies by Integrated Care Board (ICB)
  • Surgery before IVF — surgical treatment of endometriomas before IVF may improve outcomes, though evidence is mixed; discuss with a specialist
  • Ovarian reserve testing — AMH (anti-Müllerian hormone) levels may be reduced in women with extensive endometriosis

UK Support and Resources

  • Endometriosis UK — endometriosis-uk.org | Helpline: 0808 808 2227 | UK’s leading endometriosis charity with local support groups
  • BSGE Endometriosis Centres — bsge.org.uk — find your nearest specialist centre
  • The Endometriosis Consortium — endometriosis-consortium.org.uk | NHS Specialist network
  • NICE NG73 — Endometriosis: diagnosis and management — full guideline at nice.org.uk

What Major Health Sites Often Miss About Endometriosis

1. The 8-Year Diagnosis Delay — and How to Fight It

The average UK diagnosis delay for endometriosis is 8 years — women are often told their pain is normal, psychological, or due to IBS. NICE NG73 specifically states that GPs should consider endometriosis in women with recurrent pelvic pain, and that normal ultrasound does NOT rule it out. If you have been dismissed, ask specifically for a gynaecology referral to assess for endometriosis, citing NICE NG73 by name if needed.

2. The Link Between Endometriosis and Bowel Disease

Bowel endometriosis affects approximately 12% of women with endometriosis and causes symptoms almost identical to IBS — bloating, diarrhoea, constipation, and pain, all cyclically worse around periods. Many women are diagnosed with IBS when they actually have bowel endometriosis, which requires completely different treatment. If your “IBS” symptoms are cyclical and linked to your period, please discuss endometriosis with your GP or gynaecologist.

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