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[Conditions](https://durgical.com/en/conditions/) · [Pelvis](https://durgical.com/en/anatomy/region/pelvis/)

# Endometriosis

Endometriosis is a long-term disease in which tissue like the uterine lining grows outside the uterus, mostly in the [pelvis](https://durgical.com/en/anatomy/region/pelvis/); it causes pain and infertility.

Updated 2026-10-29

## Structures involved

Tap one to see what it is and open it in 3D.

- [Ovaries](https://durgical.com/en/anatomy/ovary/)
- [Rectouterine pouch](https://durgical.com/en/anatomy/rectouterine-pouch/)
- [Uterosacral ligament](https://durgical.com/en/anatomy/uterosacral-ligament/)
- [Endometrium](https://durgical.com/en/anatomy/endometrium/)
- [Uterine tubes](https://durgical.com/en/anatomy/uterine-tube/)
- [Broad ligament](https://durgical.com/en/anatomy/broad-ligament-of-uterus/)
- [Urinary bladder](https://durgical.com/en/anatomy/urinary-bladder/)
- [Rectum](https://durgical.com/en/anatomy/rectum/)
- [Ureters](https://durgical.com/en/anatomy/ureter/)

## In biochemistry

- [CA-125](https://durgical.com/en/biochemistry/topics/ca-125/)

## In histology

- [Fertilisation, implantation and the decidua](https://durgical.com/en/histology/fertilisation-implantation-and-the-decidua/)
- [Uterus and the endometrial cycle](https://durgical.com/en/histology/uterus-and-the-endometrial-cycle/)

## In physiology

- [The menstrual cycle: ovary and endometrium](https://durgical.com/en/physiology/the-menstrual-cycle-ovary-and-endometrium/)

## Why it happens

- [Chronic inflammation: causes, cells and features](https://durgical.com/en/general-pathology/chronic-inflammation-causes-cells-and-features/)
- [Actions of estrogen and progesterone](https://durgical.com/en/physiology/actions-of-estrogen-and-progesterone/)
- [Aromatase (CYP19A1)](https://durgical.com/en/biochemistry/enzymes/aromatase/)

## What it is

A chronic, oestrogen-dependent inflammatory disease in which [endometrium](https://durgical.com/en/anatomy/endometrium/) -like tissue grows outside the uterus, mostly on the pelvic [peritoneum](https://durgical.com/en/anatomy/peritoneum/), [ovaries](https://durgical.com/en/anatomy/ovary/) and uterosacral ligaments. It causes pelvic pain and infertility.

## Who gets it

Affects women and girls of reproductive age; widely cited estimates are around one in ten. Diagnosis is often delayed by years because pain is normalised, a delay also described in Latin America.

## Causes

- Retrograde menstruation with implantation on the peritoneum (Sampson theory)
- Coelomic metaplasia of peritoneal cells
- Lymphatic or vascular spread
- Immune, genetic and epigenetic factors
- Implantation in surgical scars (for example after caesarean section)

## Risk factors

- First-degree relative with endometriosis
- Early menarche, short cycles, heavy or long periods
- Nulliparity
- Obstruction of menstrual outflow (Müllerian anomalies)
- Low body mass index

## Pathophysiology

Ectopic implants respond to cyclic hormones, bleed and trigger inflammation, prostaglandin release, nerve ingrowth and fibrosis. Adhesions distort the pelvis and tubes, and ovarian endometriomas («chocolate cysts») form. The inflamed peritoneal environment impairs egg, sperm and embryo function, and chronic pain can sensitise the [nervous system](https://durgical.com/en/anatomy/system/nervous-system/).

## Classification

- Superficial peritoneal endometriosis
- Ovarian endometrioma
- Deep endometriosis (infiltrating the uterosacral ligaments, rectovaginal septum, bowel, bladder or [ureters](https://durgical.com/en/anatomy/ureter/))
- Extrapelvic disease (e.g. abdominal wall scars, [diaphragm](https://durgical.com/en/anatomy/diaphragm/), [pleura](https://durgical.com/en/anatomy/pleura/))
- Staging systems include ASRM stages I–IV and #Enzian; criteria vary and stage correlates poorly with pain

## Symptoms and signs

- Painful periods (dysmenorrhoea), often progressive and starting before bleeding
- Deep dyspareunia
- Chronic pelvic pain
- Painful defecation (dyschezia) or painful urination, often cyclical
- Infertility
- On exam: tender uterosacral nodules, fixed retroverted uterus or adnexal mass; some have no symptoms

## Red flags

- Cyclic rectal bleeding or haematuria (bowel or bladder involvement)
- Sudden severe pain with fever or peritonism (ruptured or infected endometrioma, ovarian torsion)
- Flank pain or hydronephrosis from ureteric involvement
- Complex adnexal mass with features suspicious for cancer

## Diagnosis

**Clinical**
Typical history and pelvic exam; many guidelines now accept a clinical diagnosis and empirical treatment. Laparoscopy with biopsy gives the definitive diagnosis and allows treatment at the same time.

**Tests**
Pregnancy test; no blood test confirms it (CA-125 may rise but is not specific).

**Imaging**
Transvaginal ultrasound shows endometriomas and, in expert hands, deep disease; MRI maps deep endometriosis before surgery.

## Differential diagnosis

- Pelvic inflammatory disease
- Adenomyosis
- Ovarian cyst or torsion
- Irritable bowel syndrome
- Bladder pain syndrome (interstitial cystitis)
- Ectopic pregnancy (acute pain)

## Goal of treatment

Relieve pain, improve quality of life and fertility and limit progression, with a plan based on symptoms, age and the wish for pregnancy.

## Treatment

**Medical**
NSAIDs for pain plus first-line hormonal suppression with combined hormonal contraceptives or progestins (oral, injectable or intrauterine).

**Medical**
Second line: GnRH agonists or antagonists, usually with add-back hormone therapy to protect bone; aromatase inhibitors in selected cases.

**Surgical**
Laparoscopic excision or ablation of implants, adhesiolysis and cystectomy for endometriomas; deep disease is managed by multidisciplinary teams (colorectal, urology).

**Procedure**
Assisted reproduction (such as IVF) for infertility, planned with fertility specialists.

**Rehabilitation**
Pelvic-floor physiotherapy, multidisciplinary pain care and psychological support for chronic pain.

## Drugs for this condition

- [Leuprorelin](https://durgical.com/en/pharmacology/leuprorelin/)
- [Goserelin](https://durgical.com/en/pharmacology/goserelin/)

## Complications

- Infertility
- Chronic pelvic pain and central sensitisation
- Adhesions; bowel or ureteric obstruction
- Rupture of an endometrioma; reduced ovarian reserve (also after surgery)
- Slightly higher risk of some ovarian cancers (clear-cell, endometrioid)

## Prognosis

Chronic and relapsing until menopause; symptoms often return after stopping hormones or after surgery. Most improve with treatment, and many achieve pregnancy, naturally or with assisted reproduction.

## Test yourself

Think of the answer, then tap the question to see it.

## What are the classic symptoms of endometriosis?

Dysmenorrhoea, deep dyspareunia, chronic pelvic pain and infertility.

## What is the most widely cited theory of how endometriosis starts?

Retrograde menstruation (Sampson): endometrial cells flow back through the tubes and implant on the pelvic peritoneum.

## What is an endometrioma?

An ovarian cyst lined by endometriosis and filled with old blood, called a «chocolate cyst».

## Which procedure gives a definitive histological diagnosis?

Laparoscopy with biopsy of the lesions.

## What are the first-line hormonal treatments?

Combined hormonal contraceptives or progestins, with NSAIDs for pain.

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## Related conditions

- [Uterine fibroids (leiomyomas)](https://durgical.com/en/conditions/uterine-fibroids/)
- [Pelvic inflammatory disease](https://durgical.com/en/conditions/pelvic-inflammatory-disease/)
- [Adenomyosis](https://durgical.com/en/conditions/adenomyosis/)
- [Ovarian cyst](https://durgical.com/en/conditions/ovarian-cyst/)
- [Irritable bowel syndrome](https://durgical.com/en/conditions/irritable-bowel-syndrome/)
- [Ectopic pregnancy](https://durgical.com/en/conditions/ectopic-pregnancy/)
- [Ovarian cancer](https://durgical.com/en/conditions/ovarian-cancer/)
- [Dysmenorrhoea](https://durgical.com/en/conditions/dysmenorrhoea/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Endometriosis](https://www.ncbi.nlm.nih.gov/books/NBK567777/) (StatPearls (NCBI Bookshelf), 2026).

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Source: https://durgical.com/en/conditions/endometriosis/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/endometriosis/