Endometriosis is one of the most common gynaecological conditions in the UK, yet it remains widely under-recognised, with many people living with pelvic pain for years before anyone names the cause. Because its symptoms overlap with other conditions, such as IBS and ordinary period pain, it can take a long time and several appointments before the pieces come together into a diagnosis. This guide explains what endometriosis is, how to recognise the symptoms, how it is diagnosed in the UK, the treatment options a clinician may discuss with you, and when it is worth seeing a GP.
What is endometriosis
Endometriosis is a long-term, inflammatory condition in which tissue similar to the lining of the womb (the endometrium) is found elsewhere in the body, most often in the pelvis around the ovaries, fallopian tubes and the tissue lining the pelvic cavity. This tissue responds to the hormonal changes of the menstrual cycle in a similar way to the womb lining, which can cause inflammation, pain and, over time, scar tissue or adhesions.
It is thought to affect around 1 in 10 women and people assigned female at birth of reproductive age in the UK, making it almost as common as asthma or diabetes, although awareness of it is much lower. The exact cause is not fully understood, and several theories exist, including retrograde menstruation (where menstrual blood containing endometrial cells flows back through the fallopian tubes), immune system differences, and genetic factors, since it tends to run in families. Endometriosis is not caused by anything a person has done, and it is not the same thing as having a difficult or heavy period, although the two can certainly coexist.
Recognising the symptoms
Symptoms vary a great deal between individuals, both in which ones appear and how severe they are, and some people have extensive endometriosis with very few symptoms while others have severe pain with comparatively little disease found at surgery. The most common features include:
- Chronic pelvic pain, often but not always worse in the days around a period
- Period pain that is more severe than is typical, sometimes severe enough to affect daily activities, work or school
- Pain during or after sex
- Pain when opening the bowels or passing urine, particularly around the time of a period
- Heavy periods, or bleeding between periods
- Fatigue that is out of proportion to other symptoms
- Difficulty conceiving, in some but not all cases
Because period pain is common and often dismissed as something to simply put up with, many people are not sure whether what they are experiencing is "normal" or worth raising with a clinician. As a general guide, pain that regularly stops you doing the things you would otherwise do, that does not settle with over-the-counter painkillers, or that is accompanied by any of the bowel, bladder or sexual symptoms above, is reasonable to discuss with a GP rather than manage alone indefinitely.
How endometriosis is diagnosed
There is no single, simple test that rules endometriosis in or out. NICE guidance (NG73) recommends that a transvaginal ultrasound scan is offered to anyone with suspected endometriosis, as this can pick up some, though not all, cases, particularly larger areas of disease such as an endometrioma (a cyst on the ovary). Importantly, a normal ultrasound does not rule out endometriosis, and referral to gynaecology can still be made on the basis of symptoms alone if they persist or are significantly affecting your life.
In secondary care, further assessment may include a pelvic MRI scan, and the definitive way to diagnose endometriosis is a laparoscopy, a minor surgical procedure in which a camera is passed through a small cut in the abdomen to look directly at the pelvic organs, and to take a biopsy or treat visible areas of endometriosis at the same time where appropriate.
Delays in diagnosis remain a well-recognised problem in the UK. A 2020 inquiry by the All-Party Parliamentary Group on Endometriosis reported that it takes an average of around 8 years from the start of symptoms to a confirmed diagnosis, a figure that patient charities continue to cite as a measure of how much progress is still needed. If you feel your symptoms are not being taken seriously, it is reasonable to ask directly whether endometriosis is being considered, and keeping a simple diary of your pain and cycle for a few months can help your clinician build a clearer picture.
Treatment options: pain relief, hormonal treatment and surgery
There is currently no cure for endometriosis, so treatment aims to control symptoms and improve day-to-day quality of life, with the right approach depending partly on whether you are trying to conceive. NICE advises starting with a short trial, for example around three months, of paracetamol or a non-steroidal anti-inflammatory drug (NSAID) such as naproxen or mefenamic acid, taken regularly during the days pain is expected rather than only once it has become severe.
If pain relief alone is not enough, NICE advises offering hormonal treatment, such as a combined contraceptive pill like Microgynon, or a progestogen-only option such as norethisterone, taken continuously or cyclically. These work by suppressing ovulation and thinning the tissue that responds to hormonal changes, which can meaningfully reduce pain for many people, although they are not suitable for everyone and do not treat the underlying disease. Hormonal treatment is generally not used by those actively trying to conceive, since it works partly by preventing ovulation.
When pain relief and hormonal treatment do not control symptoms well enough, or when fertility is a concern, laparoscopic surgery to remove or treat visible areas of endometriosis may be offered, usually under the care of a gynaecologist with specialist interest in the condition. Surgery can improve symptoms for many people, though endometriosis can return afterwards, so it is often used alongside other treatment rather than as a one-off fix. More specialist or complex cases are typically managed in a dedicated endometriosis centre.
Endometriosis, fertility and daily life
Many people with endometriosis conceive without any fertility treatment at all, but the condition is associated with a higher likelihood of difficulty conceiving, particularly where disease is more extensive or affects the ovaries or fallopian tubes directly. If conceiving naturally is taking longer than expected, a GP can arrange initial investigations, and referral to a fertility specialist may be appropriate depending on your age and how long you have been trying.
Beyond the physical symptoms, living with chronic pain can affect mood, relationships, sleep and the ability to work or study consistently, and this emotional impact is a recognised and valid part of the condition, not something separate from it. Patient organisations and GP-led support groups can be a useful source of practical advice alongside your clinical care, and our guide to period pain treatment and relief covers self-care measures that many people with endometriosis also find helpful alongside prescribed treatment.
When to see a doctor
It is worth seeing a GP if you have pelvic pain that regularly disrupts your daily activities, work or sleep, pain during or after sex, pain when opening your bowels or passing urine that follows your menstrual cycle, or if you have been trying to conceive for 12 months (or 6 months if you are over 35) without success. It is also worth seeking advice sooner if over-the-counter painkillers are not controlling the pain, or if you simply feel something is not right, even if you cannot describe it precisely.
An endometriosis diagnosis is rarely a single event but the start of an ongoing relationship with your GP or a specialist team, since the symptoms that matter most, and the treatments that suit you, are likely to change over time, for example moving between pain control, fertility planning and long-term management at different stages of life. Regular review allows your treatment plan to be adjusted as your circumstances change.
Endometriosis is a long-term condition, but with the right combination of pain relief, hormonal treatment and, where appropriate, surgery, most people's symptoms can be managed effectively. Our Women's Health library also covers related topics including period pain treatment and relief, combined vs progestogen-only contraception, and PCOS symptoms, diagnosis and treatment, both of which can be relevant when weighing up hormonal treatment options.