• Defined by the presence of endometrial tissue (glands and stroma) outside of the uterine cavity.
• Affects 6 to 10% of women of reproductive age, 50 to 60% of women and teenage girls with pelvic pain, and up to 50% of women with infertility.
• The most common cause of secondary dysmenorrhea in adolescents, with a mean age of presentation 25-30.
• Often the clinical starting point is ruling out critical diagnoses – ruptured ectopic, ovarian torsion, pelvic inflammatory disease, hemorrhagic ovarian cyst.
• Can be a chronic relapsing disorder that necessitates long term follow up. Ensuring adequate follow up after discharge from the ED is crucial.

Diagnosis:

• Endometriosis is definitively diagnosed by histologic evaluation of a lesion biopsied during surgery.
• A combination of symptoms, signs, and imaging findings can be used to make a presumptive, nonsurgical diagnosis of endometriosis and start initial treatment. Studies have reported an average delay of 7 to 12 years for definitive diagnosis in women with endometriosis.

Key Differential Considerations:

• Endometriosis can cause chronic, acute and acute on chronic pelvic pain.
• Acute pelvic pain in the context of endometriosis could suggest a ruptured endometrioma or ovarian torsion (increased risk from pelvic mass).
• Other critical differential diagnoses include a ruptured ectopic pregnancy, pelvic inflammatory disease and a hemorrhagic ovarian cyst.

Presentation:

• Suggested by the triad of dysmenorrhea, dyspareunia and dyschezia.
• Heavy menstrual bleeding.
• Pelvic mass.
• Less common symptoms include: bowel/bladder dysfunction and back pain, pneumothorax.
• Risk factors include 1^st degree family history, prolonged exposure to endogenous estrogen (early menarche, nulliparity, late menopause, or obesity).

Physical:

• Often normal; lack of findings does not exclude the disease.
• Supportive findings include tenderness on vaginal examination, nodules in the posterior fornix and adnexal masses.

Investigations:

• There are no pathognomonic laboratory findings for endometriosis.
• Ca 125 levels are currently not recommended.
• Beta-HCG should be done in any female of childbearing age with pelvic pain.
• Further labs should be guided by your differential diagnosis.

Imaging:

• Pelvic US (ensure follow up organized if performing as outpatient) acutely if torsion or ectopic under consideration.
• Consider MRI for refractory/atypical cases or if considering thoracic endometriosis.

1. Leyland N, Casper R, Laberge P, Singh SS; SOGC. Endometriosis: diagnosis and management. J Obstet Gynaecol Can. 2010 Jul;32(7 Suppl 2):S1-32. PMID: 21545757.

   
   

2. SOGC Endometriosis Working Group. Management of Symptoms Associated with Suspected or Confirmed Endometriosis. April 2020.

   
   

3. Giudice LC. Clinical practice. Endometriosis. N Engl J Med 2010; 362:2389-98

   
   

4. Schenken, Robert. Endometriosis: Pathogenesis, clinical features, and diagnosis. In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA.