• Clinical science

Endometriosis

Abstract

Endometriosis is a common, benign, and chronic disease in women of reproductive age that is characterized by the occurrence of endometrial tissue outside the uterus. The etiology of endometriosis is not yet fully established; however, retrograde menstruation is one of several factors involved. Symptoms include dysmenorrhea, dyspareunia, chronic pelvic pain, and infertility. Treatment is based on the individual disease manifestation and may either involve the administration of pain relievers and hormonal therapy or surgical removal of endometriotic tissue. Endometriosis tends to recur, but symptoms and disease spread improve after pregnancy in many cases, as well as in menopause.

Epidemiology

  • Age of onset: 20–40 years
  • Incidence: 2–10% of all women
  • In the US, endometriosis is more common in white and Asian women than in black and Hispanic women.

References:[1][2]

Epidemiological data refers to the US, unless otherwise specified.

Etiology

  • The etiology of endometriosis is not yet fully understood; however, retrograde menstruation seems to play a major role in the pathogenesis of endometriosis.
  • Other contributing factors include:
    • Coelomic metaplasia
    • Iatrogenic implantation
    • Hematogenic and lymphogenic dissemination of endometrial cells
    • Hereditary component

References:[1]

Classification

ASRM Classification (American Society for Reproductive Medicine)

The size, depth, and location of endometrial tissue and associated adhesions are evaluated.

Stage Disease severity Findings
I Minimal Isolated implants and no significant adhesions
II Mild Superficial implants less than 5 cm in aggregate, scattered on the peritoneum and ovaries
III Moderate Multiple implants, both superficial and invasive. Peritubal and periovarian adhesions may be evident.
IV Severe Multiple superficial and deep implants, including large ovarian endometriomas. Filmy and dense adhesions are usually present.

Pathophysiology

  • Regardless of where the endometrial tissue is located, it reacts to the hormone cycle; in much the same way as the endometrium and proliferates under the influence of estrogen.
  • Endometriotic implants: including ovaries, fallopian tubes, cervix or less commonly, the extrapelvic organs (e.g., lung or diaphragm)
    • ↑ Production of inflammatory and pain mediators
    • Nerve dysfunction
    • Altered anatomy (e.g., pelvic adhesions) → infertility

References:[1]

Clinical features

Endometriosis may also be asymptomatic in many women and appear as an incidental finding during surgery performed for another reason!

References:[1][2][3]

Diagnostics

  • Patient history
  • Physical examination
    • Rectovaginal tenderness
    • Adnexal masses
  • Transvaginal ultrasound (best initial test)
    • The uterus is generally not enlarged.
    • Evidence of ovarian cysts (chocolate cysts)
    • Nodules in bladder or rectovaginal septum
  • Laparoscopy; (confirmatory test)
  • MRI, coloscopy, cystoscopy, or other interventions are potentially indicated if endometrial cells are suspected.
  • Common locations of endometriotic implants
    • Ovaries
    • Rectouterine pouch
    • Fallopian tubes
    • Bladder

Normally the severity of the findings does not correlate with the severity of symptoms!

References:[4][1][3]

Pathology

  • Endometrial implants present macroscopically as yellow-brown (sometimes reddish-blue) blebs, islands, or pinpoint spots.
  • Gunshot lesions or powder-burn lesions: black, brown, or bluish nodules or cystic structures seen on the serosal surfaces of the ovaries and peritoneum
  • Ovarian endometriomas or chocolate cysts: cyst-like structures that contain blood, fluid, and menstrual debris
  • Fallopian tubes
  • Histologic findings
    • Normal endometrial glands
    • Normal endometrial stroma
    • Preponderance of hemosiderin laden macrophages due to cyclic hemorrhages into endometriomas

References:[1]

Differential diagnoses

  • See “Differential diagnosis of dysmenorrhea and menorrhagia
  • Adenomyosis
    • Definition: benign disease characterized by the occurrence of endometrial tissue within the uterine wall
    • Epidemiology: : peak incidence at 35–50 years
    • Etiology: The exact etiology is unknown, though some risk factors have been identified:
    • Clinical features
      • May be asymptomatic
      • Dysmenorrhea
      • Menorrhagia
      • Chronic pelvic pain, aggravated during menses
      • Uniformly enlarged uterus, tender on palpation
    • Diagnostics
      • Diagnosis is clinical and may be supported by transvaginal ultrasound and MRI findings
        • Myometrial wall thickening
        • Myometrial cysts
        • Linear striations exiting the endometrium
        • Poorly defined endomyometrial border
        • Increased myometrial heterogeneity
      • Histology serves to confirm the diagnosis.
    • Treatment
      • Conservative: combined oral contraceptives , progestin-only contraception (e.g., IUD, continuous-use contraceptive pill), NSAIDs for pain relief
      • Surgical: Hysterectomy is the definitive treatment.

References:[5][6][7]

The differential diagnoses listed here are not exhaustive.

Treatment

  • Medical therapy
    • Mild to moderate pelvic pain without complications
    • Severe symptoms
      • GnRH agonists (e.g., buserelin, goserelin) and estrogen-progestin OCPs
        • Effect: FSH/LH levels
        • Suppression of ovariesestrogen level
  • Surgical therapy
    • First-line: laparoscopic excision and ablation of endometrial implants
      • To confirm the diagnosis and exclude malignancy (see “diagnostics” above)
      • If there is a lack of response to medical therapy
      • Treat expanding endometriomas and complications (e.g., bowel/bladder obstruction, rupture of endometrioma, infertility)
    • Second-line: : open surgery with hysterectomy with or without bilateral salpingo-oophorectomy
      • Treatment-resistant symptoms
      • No desire to bear additional children

References:[4][1][8][7][9]

Complications

References:[1][2][11]

We list the most important complications. The selection is not exhaustive.