Endometriosis
Endometriosis is a chronic inflammatory condition in which endometrium-like tissue grows outside the uterus, most commonly within the pelvis.
Updated UKMLA guide to endometriosis based on primarily on NICE guideline NG73: causes, risk factors, symptoms, complications, diagnosis, and management.
Definition
Endometriosis is a chronic inflammatory disease defined by the growth of endometrium-like tissue outside the uterus.
Endometrium-like tissue deposits are most commonly distributed in the pelvis:
- Ovaries
- Uterosacral ligaments
- Pouch of Douglas
- Rectum and sigmoid colon
- Bladder
- Distal ureter
The more common pelvic or abdominal cavity endometriosis is divided into three subtypes: [Ref]
- Superficial peritoneal endometriosis: lesions on the peritoneal surface of the abdominal / pelvic viscera
- Endometrioma (“chocolate cysts” / ovarian endometriosis): cysts within the ovary, lined by endometrial gland and stroma
- Deep endometriosis: involvement of the bowel / bladder / ureter OR lesions that penetrate the pelvic peritoneal surface (e.g. uterosacral ligaments)
- Often defined as lesions with >5 mm depth of invasion beneath the peritoneum
Extrapelvic endometriosis is possible, affecting the diaphragm, thoracic cavity, abdominal wall, brain etc. but it is rare.
Epidemiology
Endometriosis is one of the most common gynaecological disorders in women of reproductive age.
- Endometriosis is estimated to affect ~10% of women of reproductive age
- Most commonly diagnosed between 18-29 y/o
Causes and Pathophysiology
The exact cause of endometriosis remains unknown, likely to be multifactorial in origin.
A most commonly taught theory is retrograde menstruation, where endometrial cells flow backwards from the uterine cavity through the fallopian tubes and implant on pelvic organs.
However, up to 90% of women experience some form of retrograde menstruation, yet most do NOT develop endometriosis. This also does not explain why endometriosis occurs in some women after hysterectomy or, rarely, in some men following exposure to oestrogen through drug treatments.
Other theories include:
- Lymphatic or circulatory dissemination of endometriotic tissue
- Genetic predisposition – well documented, but no specific gene has been identified
- Müllerian remnants
- Immune dysfunction
- Metaplasia (e.g. peritoneal mesothelium transforms into endometrial-type cells)
Risk Factors
Many risk factors for endometriosis are non-specific epidemiological associations and are not sufficiently predictive to rule in or rule out the disease. [Ref]
- Family history
- 7-10x risk if a 1st degree relative has endometriosis
- Factors that increase lifetime menstrual exposure
- Early menarche
- Short menstrual cycles
- Nulliparity
- Factors that increase retrograde menstruation exposure
- Vaginal outflow obstruction
- Heavy menstrual bleeding
- White ethnicity
- Low BMI
- Autoimmune disease
Clinical Features
Course of disease: Endometriosis is a chronic disease with no curative treatment
- In most affected individuals, symptoms begin in adolescence and improve after menopause
- It is not inevitably progressive; it can remain stable, regress, or progress with time
Patients with endometriosis may be asymptomatic. Pain is a primary complaint, there are 3 main types of presentation: [Ref1][Ref2]
| Category | Symptoms |
|---|---|
| Cyclical pain (menstrual-related) |
Cyclic bowel and bladder pain helps distinguish endometriosis from non-gynaecological causes of abdominopelvic discomfort. |
| Chronic pain (non-menstrual-related) |
|
| Activity-related |
|
Infertility commonly coexists with pain as a presenting feature of endometriosis.
Possible examination findings:
- Reduced organ mobility and enlargement
- Fixed retroverted uterus
- Enlarged tender ovary (endometrioma)
- Tender nodularity in the posterior vaginal fornix
- Visible vaginal endometriotic lesions
A normal examination does NOT exclude endometriosis.
Complications
Key complications include:
- Infertility – common
- The underlying mechanism is poorly understood, and causation is not established
- Severe disease can lead to tubal adhesions (resulting in marked distortion of pelvic anatomy and pelvic pain), reduced ovarian reserve and oocyte and embryo quality, and poor implantation
- Endometriosis can also impair fertility by disturbing the function of the fallopian tube, embryo transport, and the eutopic endometrium
- Endometriomas (chocolate cyst) – ovarian cysts containing blood and endometriosis-like tissue
- Risk of rupturing
- May affect fertility by distorting pelvic anatomy
- ↑ Risk of ovarian cancer
- Almost 2x increased risk but this represents a very small lifetime risk
- Adhesion formation – may cause chronic pain
- Chronic pain and reduced quality of life
Investigation and Diagnosis
1st line: TVUSTransvaginal ultrasound
- Normal findings are common and do NOT exclude endometriosis
- Primary purpose is to identify endometriomas, locate deep endometriosis (e.g. bowel, bladder, ureter) and exclude other pathologies
- If patient declines TVUSTransvaginal ultrasound → TAUSTrans-abdominal ultrasound
Possible ultrasound findings in endometriosis: [Ref]
- Ovarian endometrioma (chocolate cyst) → homogenous unilocular cyst with minimal blood flow on Doppler
- Deep endometriosis → irregular hypoechoic nodules (e.g. uterosacral ligaments, rectovaginal septum, rectosigmoid)
Gold standard: laparoscopy
- A definitive diagnosis can only be made by directly visualising endometriotic lesions in the abdomen and pelvis, which can appear as: [Ref]
- Superficial red, blue-black, or white/fibrotic implants on the peritoneal surface
- Ovarian endometriomas – “chocolate cysts” with dark, haemosiderin-laden fluid
- Deep infiltrating endometriosis – nodules penetrating >5mm into tissue (uterosacral ligaments, rectovaginal septum, bladder, bowel)
- Adhesions – fibrous bands distorting pelvic anatomy
- Biopsy can be considered, but -ve histology does not exclude endometriosis
Other tests:
- Pelvic MRI – consider to diagnose deep endometriosis and assess its extent (in secondary care)
CA125 should NOT be used to diagnose endometriosis. Endometriosis can increase CA125 level but it has no diagnostic value.
Management
Medical and surgical treatments can often provide symptomatic relief but are not curative.
Asymptomatic Endometriosis
Expectant management with observation is sufficient for most patients [Ref]
Treatment is generally reserved for symptomatic OR complicated asymptomatic cases (e.g., hydronephrosis, large cysts)
General Symptomatic Endometriosis
Pain Management
1st line: short trial of paracetamol and/or NSAID
If the patient is not planning to conceive, hormonal treatment can be offered:
- COCPCombined oral contraceptive pill, or
- A progestogen (LNG-IUSLevonorgestrel intrauterine system / medroxyprogesterone acetate injection / etonogestrel implant)
Surgical Management
1st line: laparoscopic surgery / intervention
- Indications include
- At the time of diagnostic laparoscopy if there is uncomplicated ovarian endometrioma or superficial peritoneal endometriosis
- Deep endometriosis may require further surgical planning beyond the diagnostic laparoscopy + consider pre-operative GnRH agonist for 3 months
- To improve fertility (see section below for more details)
- Pharmacological management failed / not tolerated / contraindicated
- Techniques
- Superficial peritoneal endometriosis → excision or ablation + adhesiolysis
- Endometriomas → consider excision (cystectomy) over ablation
Consider post-operative hormonal therapy (e.g. COCP or progestogen) to prolong the benefits of surgery and manage symptoms
Last resort: hysterectomy
- Recommended procedure: laparoscopic hysterectomy +/- oophorectomy + excision of all endometriotic lesions
- Indications include [Ref]
- Failure of other therapies (medical and laparoscopic interventions)
- Completed family (no desire for future pregnancy)
- Co-existing adenomyosis or HMBHeavy menstrual bleeding refractory to other treatments
Infertility in Endometriosis
The management of endometriosis-related subfertility must involve a multidisciplinary team, including input from a fertility specialist.
Initial management: discuss either of the following options:
- Expectant management for up to 2 years (including time already spent trying to conceive before assessment), or
- Surgical treatment (laparoscopic surgery / interventions)
Offer pain management with paracetamol or NSAIDs
For laparoscopic surgery / interventions:
- Excision or ablation + adhesiolysis for superficial peritoneal endometriosis
- Ovarian endometrioma: ablation and drainage may preserve the ovarian reserve more than cystectomy (excision)
If expectant management and surgical treatment failed or are not appropriate:
- Intrauterine insemination with ovarian stimulation (gonadotrophins)
- IVFIn vitro fertilisation
Do NOT offer hormonal treatment (i.e. COCP, progestogens, GnRH agonist) – they do NOT improve spontaneous pregnancy rates.
References
NICE guideline Endometriosis: diagnosis and management
NICE CKS Endometriosis
NICE guideline Fertility problems: assessment and treatment 1.36 Endometriosis