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Women's Health

Endometriosis

Endometriosis is endometrium-like tissue outside the uterine cavity that causes inflammation, pain and fibrosis; suspect it from period-related pelvic, bowel, urinary or sexual symptoms, investigate and treat in parallel, and tailor decisions to pain, fertility and disease location.

In a nutshell

Suspect endometriosis from chronic or period-related pelvic pain, dysmenorrhoea affecting life, deep dyspareunia, cyclical bowel or urinary symptoms or subfertility. NICE recommends transvaginal ultrasound for everyone with suspected disease, with initial treatment and referral in parallel; a normal scan does not exclude it.

Classic presentation

A person with period-related pelvic pain, deep dyspareunia and painful bowel movements or subfertility, sometimes with a normal examination and ultrasound.

Key points

  • Endometriosis is endometrium-like tissue outside the uterine cavity; its exact cause is not proven and retrograde menstruation is only one proposed mechanism.
  • Suspect it in chronic pelvic pain, disabling dysmenorrhoea, deep dyspareunia, cyclical bowel or urinary symptoms, or infertility associated with these features, including in adolescents.
  • Offer transvaginal ultrasound to all suspected cases even if examination is normal; a normal scan does not exclude endometriosis.
  • Start analgesic and hormonal treatment, ultrasound and referral in parallel; do not delay management until laparoscopy.
  • Refer endometrioma, deep bowel/bladder/ureteric disease or extra-pelvic disease to a specialist endometriosis centre.
  • If trying to conceive, hormonal treatment does not improve spontaneous pregnancy rates; involve fertility specialists and discuss surgery, ovarian reserve and assisted reproduction.

First-line investigation

Symptom and pelvic assessment with transvaginal ultrasound for all suspected cases; specialist ultrasound or MRI maps deep disease, and laparoscopy is considered when the result will guide diagnosis or treatment.

Management

Recognise and assess

  • Suspect endometriosis from period-related or chronic pelvic, sexual, bowel or urinary symptoms and assess pain, daily impact, fertility priorities and acute red flags.1,2

Investigate in parallel

  • Offer transvaginal ultrasound even when examination is normal, start appropriate symptom treatment and arrange referral in parallel; a normal scan does not exclude disease.1

Control pain

  • Discuss analgesic risks and preferences, consider a short paracetamol or NSAID trial and offer combined-pill or progestogen treatment when pregnancy is not currently being pursued.1,3

Refer and treat specialist disease

  • Refer persistent or disabling symptoms to gynaecology and endometrioma, deep bowel/bladder/ureteric or extra-pelvic disease to a specialist endometriosis centre; consider specialist imaging, laparoscopy and surgery according to priorities.1

Protect fertility and monitor recurrence

  • When fertility is a priority, involve fertility specialists and do not use hormonal treatment to improve spontaneous conception; after surgery, consider hormonal symptom suppression only when pregnancy is not being pursued and arrange monitoring for deep disease or larger endometriomas.1,4,5

Exam traps

  • A normal pelvic examination or ultrasound does not rule out endometriosis.
  • Do not call laparoscopy the mandatory gold standard for every diagnosis; NICE allows clinical treatment, imaging and referral in parallel and considers laparoscopy when it will guide care.
  • Symptom severity does not reliably predict the extent of visible disease.
  • Do not use serum CA125 to diagnose endometriosis.
  • Hormonal treatment can reduce pain without permanently harming future fertility, but it should not be used to improve spontaneous conception when actively trying to conceive.
  • An endometrioma or deep bowel, bladder or ureteric disease needs specialist-centre referral rather than routine general gynaecology follow-up.

Illustrations

Retrograde menstruation mechanismDiagram showing endometrial-like cells refluxing through the fallopian tubes during menstruation and implanting on pelvic peritoneum and ovaries; the diagram should be presented as a proposed mechanism rather than the sole cause.PassFinals · original
Superficial peritoneal endometriosis at laparoscopyLaparoscopic view showing an arrowed blue-black superficial endometriotic implant on the pelvic peritoneum with adjacent fibrous adhesions.Stefano Di Michele et al, Wikimedia Commons · CC-BY-4.0
Common sites of endometriosisDiagram of the pelvis marking common implantation sites: ovaries, uterosacral ligaments, pouch of Douglas, bladder and bowel.PassFinals · original

Key sources

  1. NICE NG73: Endometriosis: diagnosis and management (Current NICE guidance for symptoms, person-centred pain and hormonal treatment, parallel ultrasound and referral, specialist imaging, laparoscopy, specialist-centre referral, surgery, monitoring and fertility-priority management; last updated 11 November 2024 and last reviewed 2 September 2025.)
  2. NHS: Endometriosis (Current NHS information on symptoms, diagnosis, treatment, fertility, specialist referral and urgent symptom advice.)
  3. BNF online: current analgesic and hormonal prescribing information (Use the current BNF and local specialist protocol for analgesic, hormonal, GnRH agonist or antagonist choice, dosing, contraindications, add-back therapy and monitoring; no fixed dose is reproduced here.)
  4. NICE TA1067: Linzagolix with hormonal add-back therapy for treating symptoms of endometriosis (Current NICE technology appraisal option for adults of reproductive age after medical or surgical treatment, subject to the recommendation and marketing authorisation conditions.)
  5. NICE TA1057: Relugolix–estradiol–norethisterone for treating symptoms of endometriosis (Current NICE technology appraisal option for adults of reproductive age after medical or surgical treatment, subject to the recommendation and marketing authorisation conditions.)

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.