Endometriosis
By The Treatment Registry editors
A chronic gynaecological condition in which endometrial-like tissue grows outside the uterus, causing pelvic pain, painful periods, painful intercourse, and infertility. Severity ranges from minimal disease (microscopic deposits) to severe deep-infiltrating endometriosis affecting bowel or bladder. Treatment is staged from hormonal medical management through laparoscopic excision and may include fertility treatment when conception is the priority.
Clinical overview
Signs and symptoms
Endometriosis is a chronic condition in which endometrial-like tissue grows outside the uterus. Common symptoms include painful periods, chronic pelvic pain, painful sex, painful urination or bowel movements, fatigue, heavy menstrual bleeding and infertility, although some individuals have no symptoms while others experience severe, life-altering pain. The degree of pain is only weakly related to the anatomical extent of disease. Symptoms typically begin in adolescence or the early 20s and usually ease after menopause as oestrogen levels decline. Pain often follows a cyclical pattern, intensifying during menstruation, and may be accompanied by bloating, constipation, diarrhoea and nausea. Deep infiltrating disease in the bowel or bladder can cause obstruction and cyclical blood in the stool or urine.
Causes and risk factors
The cause of endometriosis is not fully understood. The leading theory for pelvic disease is retrograde menstruation, in which menstrual blood and tissue flow backward through the fallopian tubes into the peritoneal cavity; other proposed mechanisms include local transformation of peritoneal cells (coelomic metaplasia) and spread via the lymphatic or circulatory system. It is an inflammatory disease, and lesions can trigger adhesions, fibrosis and cysts. Genetics accounts for around half of the risk: a first-degree relative with the condition confers a three- to nine-fold higher risk, and around eighty genetic loci have been associated. Hormonal and immune dysfunction, and angiogenesis, are implicated. Risk factors include obstructed menstrual outflow, a first period before age 12, a menstrual cycle shorter than 28 days, low BMI, nulliparity, and exposure to endocrine-disrupting pollutants.
How it is diagnosed
Endometriosis may be suspected in women with chronic pelvic pain, painful periods affecting daily life, pain during sex, cyclical bowel or urinary symptoms, or infertility. Assessment begins with a health history and physical examination, which may reveal nodularity or tenderness behind the uterus or reduced uterine mobility, though a normal examination does not exclude the disease. A presumed diagnosis can be made from symptoms combined with transvaginal ultrasound or MRI imaging, though not all lesions are visible on imaging. Laparoscopy (keyhole surgery) with biopsy remains the most accurate method and the gold standard, but practice has shifted away from requiring surgical confirmation to avoid treatment delays. There are no validated blood tests.
Who it affects
Endometriosis affects approximately 10% of women of reproductive age, corresponding to nearly 200 million girls and women worldwide; around 22 million had a surgically confirmed diagnosis as of 2021. It is typically diagnosed when women are in their 30s, although symptoms usually start in the early 20s or in adolescence. Up to 4% of women still have endometriosis after menopause, most commonly ovarian disease. Prevalence in trans men is comparable, at around 9%.
Clinical overview sourced from encyclopaedic medical reference; see sources below. General information only — not a substitute for individual clinical assessment.
Treatment ladder
Conservative options are first-line where appropriate; surgical options are typically reserved for cases where lower-tier options are unsuitable or have failed. Decisions are individual and depend on clinical assessment.
Conservative
- Combined hormonal contraception
First-line medical therapy for symptomatic endometriosis when pregnancy is not currently desired. Suppresses ovulation and menstrual flow, often substantially reducing pain.
- Progestin-only therapy (oral or IUS)
Alternative or second-line option; particularly useful when oestrogen is contraindicated. The levonorgestrel intrauterine system is well-evidenced for symptom control.
- GnRH analogues
Hormonal suppression producing a temporary menopausal state. Effective for severe symptoms but limited in duration by bone-density and other oestrogen-deficiency effects unless add-back therapy is used.
Procedural
- Diagnostic and operative laparoscopy
Direct visualisation and biopsy of suspected lesions remains the diagnostic gold standard for endometriosis. Visible disease can be ablated or excised in the same procedure.
- IVF / ICSI · View procedure page
Indicated for fertility preservation or treatment in patients with endometriosis-related infertility, often after or instead of further surgical management.
Surgical
- Laparoscopic excision of endometriosis
Specialist surgical excision of endometriotic deposits with preservation of fertility where possible. Outcomes substantially better with surgeons specifically trained in advanced endometriosis surgery.
- Hysterectomy with bilateral salpingo-oophorectomy
Considered in patients who have completed family planning and have severe refractory symptoms. Hysterectomy alone does not always cure endometriosis if extra-uterine disease remains.
Related procedures
Sources
- [1]ESHRE — Guidelines for Good Practice in IVF Laboratories — eshre.eu(accessed 2026-05-09)
- [2]Wikipedia — Endometriosis — en.wikipedia.org(accessed 2026-07-24)
Sources marked “on file” are held by The Treatment Registry but are not publicly accessible.