What is the diagnostic approach to endometriosis?

Diagnostic Approach to Endometriosis

Laparoscopy with histologic confirmation is the gold standard for diagnosing endometriosis, as it allows visualization of endometriotic lesions and provides the only universally accepted definitive diagnosis. 1

Initial Diagnostic Evaluation

• First-line diagnostic investigations include a targeted physical examination and pelvic ultrasound 1, 2, 3
• Physical examination should assess:
  • Mobility, fixation, and/or tenderness of the uterus
  • Site-specific tenderness in the pelvis
  • Speculum examination and vaginal palpation for nodularity or tenderness 3
• Transvaginal ultrasound (TVUS) is the preferred initial imaging modality and can effectively detect both ovarian and non-ovarian endometriosis 1
  • Endometriomas typically appear as adnexal or ovarian masses with homogenous low-level internal echoes
  • Presence of echogenic foci in the wall or multilocularity increases likelihood of endometrioma diagnosis 1
  • Dynamic ultrasound assessment, including uterine sliding sign, aids in diagnosis 1

Advanced Imaging Techniques

• If initial findings are inconclusive or deep infiltrating endometriosis is suspected, proceed to:
  • Expanded protocol TVUS performed by experts (requires special training and at least 40 examinations to develop proficiency) 1
  • MRI pelvis (82-90% sensitivity and 91-98% specificity for diagnosing endometriomas) 1
  • Transrectal ultrasound (especially for rectovaginal disease - 97% sensitivity and 96% specificity) 1
• MRI is particularly useful when:
  • TVUS findings are indeterminate
  • Assessment for deep infiltrating endometriosis is required
  • Detection of signs of adhesions is needed 1

Definitive Diagnosis

• Laparoscopy with histologic confirmation remains the gold standard for diagnosing endometriosis 1, 4, 5
• Only experienced surgeons familiar with various appearances of endometriosis should rely on visual inspection alone 1
• Peritoneal biopsy should be used to diagnose questionable peritoneal lesions 1
• The American Society for Reproductive Medicine recommends that surgeons complete classification documentation using:
  • r-ASRM (revised American Society for Reproductive Medicine) classification for all patients
  • Enzian classification for patients with deep endometriosis
  • EFI (Endometriosis Fertility Index) for patients with fertility concerns 1

Common Pitfalls and Caveats

• Serum CA-125 has limited utility as a diagnostic marker, especially for minimal or mild disease 1
• CT is not recommended for the initial imaging evaluation of suspected endometriosis 1
• Doppler assessment is important, as endometrial implants have limited vascularity; presence of Doppler blood flow in a suspected implant should prompt investigation for neoplasm 1
• Some forms of endometriosis, such as "subtle" or microscopic endometriosis, remain controversial regarding their clinical significance 1
• The correlation between laparoscopic observations and histological findings is often low, highlighting the importance of histopathologic confirmation 5
• Diagnostic delays are common due to challenges in diagnosis, which can negatively impact quality of life 4, 6

Diagnostic Algorithm

1. Initial evaluation: Targeted physical examination and transvaginal ultrasound 1, 2, 3
2. If findings suggest endometriosis or are inconclusive:
   • For suspected deep infiltrating endometriosis: Proceed to expanded protocol TVUS, MRI, or transrectal ultrasound 1
   • For suspected ovarian endometriomas: TVUS is usually sufficient; MRI if findings are indeterminate 1
3. Definitive diagnosis: Laparoscopy with histologic confirmation 1, 5
4. Classification: Use appropriate classification systems (r-ASRM, Enzian, EFI) based on patient presentation 1