Endometriosis

Endometriosis is the presence of endometrial-like tissue outside the uterine cavity, most commonly on the ovaries (endometriomas, "chocolate cysts"), pelvic peritoneum, and uterosacral ligaments, less commonly the bowel, bladder, or, rarely, distant sites.

This ectopic tissue responds to cyclical hormonal changes, causing local inflammation, fibrosis, and adhesion formation, which together drive the characteristic pain and subfertility associated with the condition.

It affects roughly 10% of women of reproductive age, and diagnostic delay from symptom onset to confirmed diagnosis remains a well recognized problem, often spanning several years.

• Secondary dysmenorrhoea, often severe and progressively worsening
• Deep dyspareunia, particularly with deep penetration, reflecting uterosacral or pouch of Douglas involvement
• Chronic pelvic pain, not confined to menstruation
• Cyclical or perimenstrual bowel or bladder symptoms (dyschezia, hematochezia, or dysuria/hematuria) where bowel or bladder involvement is present
• Subfertility, present in a substantial proportion of affected women, from a combination of anatomical distortion, adhesions, and altered pelvic and ovarian environment
• Examination may reveal a fixed, retroverted uterus, uterosacral nodularity or tenderness, or a palpable adnexal mass (endometrioma), though examination is frequently normal, particularly in earlier or more superficial disease

• Transvaginal ultrasound is useful for identifying endometriomas and deep infiltrating disease involving the bowel or bladder, but has limited sensitivity for superficial peritoneal disease, which represents a large proportion of cases
• MRI provides further characterization, particularly for deep infiltrating disease and pre-surgical planning
• Laparoscopy with histological confirmation remains the diagnostic gold standard, though current guidelines increasingly support starting empirical treatment based on clinical history and examination alone (without requiring laparoscopic confirmation first) in women with a classic presentation, given the diagnostic delay and morbidity associated with waiting for surgical confirmation
• No blood test (including CA-125) has adequate sensitivity or specificity for diagnosis

• Analgesia: NSAIDs as per the Dysmenorrhoea entry, though often insufficient alone in significant disease
• Hormonal suppression is first line medical management and can be started empirically without a laparoscopic diagnosis: combined oral contraceptive (continuous/extended cycle use often more effective for pain control than cyclical use), the levonorgestrel-releasing IUD, or progestogen-only options (desogestrel pill, or medroxyprogesterone acetate injection)
• GnRH agonists (e.g. goserelin depot injection) induce a temporary medical menopause and are highly effective for pain, but are generally reserved for second line use given menopausal side effects, and are typically used with "add-back" HRT to mitigate bone density loss and vasomotor symptoms if used beyond 6 months
• GnRH antagonists (e.g. elagolix, where available) offer an oral alternative with a different side effect profile
• Surgical management (laparoscopic excision or ablation of endometriotic deposits, with excision generally preferred given better evidence for symptom and fertility outcomes) is considered for confirmed disease not responding to medical therapy, significant endometriomas, or where fertility is a priority and anatomical distortion is contributing to subfertility
• Endometrioma management: surgical excision (cystectomy) is generally preferred over drainage/ablation alone given lower recurrence rates, though this carries a small risk of reducing ovarian reserve, a discussion particularly relevant where fertility preservation is a priority
• Fertility considerations: referral to fertility services (including consideration of IVF) is appropriate where subfertility is present and conservative or surgical management has not achieved pregnancy within a reasonable timeframe
• Severe, deep infiltrating disease (bowel, bladder, or ureteric involvement) requires management at a specialist endometriosis center with multidisciplinary surgical input

Referral: gynecology for suspected endometriosis based on clinical history, even without imaging confirmation; specialist endometriosis center for deep infiltrating disease or complex surgical needs; fertility services where subfertility is a concern.