Endometriosis is a common condition in which tissue similar to the lining of the womb grows outside it — usually in the pelvis. It causes pain that is often dismissed as "just bad periods," and on average women wait years for a diagnosis. This page explains the symptoms, how it is diagnosed, and what treatments help.

What endometriosis is

Tissue similar to the womb lining grows in places it should not: on the ovaries, the ligaments supporting the womb, the outer surface of the womb, and sometimes the bowel or bladder.

This tissue responds to the same monthly hormone changes as the lining of the womb — it thickens and bleeds. But unlike the womb lining, it has no way out. The trapped blood causes inflammation, scarring, and adhesions that stick organs together.

Endometriosis affects roughly 1 in 10 women of reproductive age.1

Symptoms

Endometriosis should be suspected if you have one or more of the following:2

  • Period pain severe enough to affect daily life — pain that stops you working, studying or sleeping is not normal
  • Pelvic pain lasting 6 months or more
  • Deep pain during or after sex
  • Bowel symptoms that follow your cycle — particularly pain on opening your bowels
  • Urinary symptoms that follow your cycle — pain passing urine, or blood in the urine
  • Difficulty getting pregnant, together with any of the above

Two things are worth knowing. First, the amount of endometriosis does not predict the amount of pain. Extensive disease can cause little pain, and a small amount can cause severe pain. Second, a family history matters — endometriosis in a mother or sister makes it more likely in you.2

If your periods regularly stop you doing normal things, please have it looked at. Severe period pain is common, but it is not normal.

How endometriosis is diagnosed

You do not need an operation before treatment can start — and because many people still believe otherwise, it is worth explaining how diagnosis actually works now.

Examination and ultrasound come first

You should be offered an internal examination, and a transvaginal ultrasound scan — a scan through the vagina. Current guidance recommends this scan for everyone with suspected endometriosis, even if the examination was normal.2 It looks for endometriosis cysts on the ovaries and for deep disease involving the bowel, bladder or ureter, and it rules out other causes of the same symptoms.

If a transvaginal scan is not suitable or not wanted, a scan through the abdomen can be done instead.2

A normal scan does not rule it out

This point matters more than any other on this page. A normal examination and a normal scan do not exclude endometriosis.2 Superficial disease frequently does not show on a scan. If your symptoms fit, you should still be taken seriously and still be referred if needed.

Treatment can start before any diagnosis is confirmed

Investigations and treatment run alongside each other, not one after the other.2 You do not have to wait for a confirmed diagnosis before starting treatment for the pain — and blood tests such as CA125 should not be used to diagnose endometriosis.2

Laparoscopy — definitive, but not the first step

A laparoscopy — keyhole surgery to look inside the pelvis — is the only way to see endometriosis directly and confirm the diagnosis definitively. It can be considered even when the scan or MRI was normal.2

What has changed is its position in the pathway. Laparoscopy is no longer the required first step. It is offered where it will change management: where treatment has not worked, where the diagnosis is genuinely uncertain, or where surgery is being considered in its own right. During the operation, endometriosis that is found can often be treated at the same time.2

If a thorough laparoscopy is completely normal, endometriosis is unlikely, and other causes of your symptoms should be looked into.2

Treatment

Treatment is chosen according to your symptoms and your priorities — not the stage of the disease.2 Two women with identical findings may reasonably be treated quite differently.

Pain relief

A trial of paracetamol or an anti-inflammatory painkiller, alone or together, is a reasonable first step for period-related and pelvic pain.2 If that is not controlling things after a few months, say so rather than continuing indefinitely — other options exist.

Hormonal treatment

Hormonal treatment reduces pain in most women by suppressing the monthly cycle, so the endometriosis is not repeatedly stimulated. The usual options are the combined oral contraceptive pill or a progestogen.2

An important reassurance: hormonal treatment does not cause any permanent harm to your future fertility.2 Many women worry that taking the pill for years will make it harder to conceive later. It does not.

Surgery

Surgery is considered when medicines have not worked, when symptoms are severe, or when there is deep disease. It is done by keyhole wherever possible.2

Endometriosis found during a laparoscopy can be removed or destroyed at the same time. Cysts on the ovaries (endometriomas) can be removed, and your surgeon will weigh this against the effect on the ovary's egg reserve — a particularly important consideration if you may want children.2

After surgery, hormonal treatment is often continued to prolong the benefit and reduce the chance of symptoms returning.2

Hysterectomy

Removing the womb is considered in specific situations — for example alongside adenomyosis or heavy bleeding that has not responded to anything else. If it is done, all visible endometriosis should be removed at the same time, otherwise symptoms can persist.2 It is a significant decision with a long discussion attached, and it is not a routine treatment for endometriosis. See our article on laparoscopic hysterectomy.

Endometriosis and fertility

Endometriosis can make conception harder, but most women with endometriosis do conceive. The management is genuinely different when you are trying to become pregnant — for example, hormonal treatments that help pain do not help conception, and the surgical decisions are weighed differently.

Because it is a distinct topic, we cover it separately: see our article on endometriosis and fertility.

Living with endometriosis

  • Keep a pain and symptom diary. It makes the consultation far more productive than trying to remember.2
  • Ask about pain management if the pain persists despite treatment. Long-standing pelvic pain sometimes needs a different approach from period pain.
  • Please be cautious with herbal remedies. The evidence does not support them for endometriosis, and some interact with other medicines.2
  • Say if it is affecting your mood, work or relationship. It commonly does, and that is part of the condition rather than a separate complaint.

When to see a doctor

Please make an appointment if you have:

  • Period pain that stops you doing normal activities
  • Pelvic pain that has lasted 6 months or more
  • Pain during or after sex
  • Cyclical bowel or bladder symptoms
  • Difficulty conceiving after a year of trying, or six months if you are over 35
  • Symptoms that keep coming back after treatment

The takeaway

Endometriosis is common, often missed, and very treatable. You should be offered an examination and an ultrasound scan — and a normal scan does not rule it out. Treatment for pain can start straight away, without waiting for surgery to confirm anything. Laparoscopy remains the definitive test, but it is a step taken when it will change your management, not a hurdle to clear first.

References

  1. NHS. Endometriosis [Internet]. London: NHS; [cited 2026 Jul 22]. Available from: https://www.nhs.uk/conditions/endometriosis/
  2. National Institute for Health and Care Excellence. Endometriosis: diagnosis and management (NG73) — Recommendations [Internet]. London: NICE; updated 2024 [cited 2026 Jul 22]. Available from: https://www.nice.org.uk/guidance/ng73/chapter/recommendations
  3. National Institute for Health and Care Excellence. Endometriosis: diagnosis and management (NG73) — Information for the public [Internet]. London: NICE; [cited 2026 Jul 22]. Available from: https://www.nice.org.uk/guidance/ng73/informationforpublic