What is the recommended approach for investigating endometriosis?

Investigation of Endometriosis

Transvaginal ultrasound (TVUS) is the recommended first-line imaging modality for investigating suspected endometriosis, with laparoscopy and histologic confirmation remaining the gold standard for definitive diagnosis when imaging is inconclusive or surgical planning is needed. 1

Initial Diagnostic Approach

Clinical Assessment

• Perform a speculum examination and vaginal palpation to assess uterine mobility, fixation, tenderness, and site-specific pelvic tenderness 2
• Evaluate for dysmenorrhea, dyspareunia, dyschezia, chronic pelvic pain, and infertility in the history 2

First-Line Imaging: Transvaginal Ultrasound

• TVUS is the preferred initial imaging modality, particularly when combined with real-time physical examination, as it can effectively detect both ovarian and non-ovarian endometriosis 1
• Look for endometriomas appearing as adnexal or ovarian masses with homogenous low-level internal echoes; echogenic foci in the wall or multilocularity increases diagnostic likelihood 1
• Assess the uterine sliding sign during dynamic ultrasound evaluation 1
• Standard TVUS has limitations; expanded protocol TVUS performed by experts (requiring at least 40 examinations for proficiency) evaluates uterosacral ligaments, anterior rectosigmoid wall, appendix, and diaphragm with significantly higher sensitivity 3, 1

Second-Line Imaging

When to Escalate Imaging

• If TVUS findings are inconclusive, deep infiltrating endometriosis is suspected, or surgical planning is required, proceed to MRI pelvis 1

MRI Protocol

• MRI demonstrates 82-90% sensitivity and 91-98% specificity for diagnosing endometriomas 1
• Use tailored protocols with moderate bladder distention and vaginal contrast to improve lesion conspicuity 3, 1
• MRI can detect adhesion signs including fixed retroverted uterus, low-signal intensity bands, and obliterated organ interfaces 1

Specialized Ultrasound for Deep Disease

• Transrectal ultrasound achieves 97% sensitivity and 96% specificity for rectovaginal endometriosis, and 80% sensitivity with 97% specificity for uterosacral ligament implants 1

Definitive Diagnosis

Laparoscopy with Histology

• Laparoscopy with histologic confirmation is the gold standard, providing the only universally accepted definitive diagnosis 1, 4
• Histologic examination is particularly important for lesions with non-classical appearance 1
• Only experienced surgeons familiar with various endometriosis appearances should rely on visual inspection alone 1
• Peritoneal biopsy should be performed for questionable peritoneal lesions 1

Surgical Classification Documentation

• Complete the r-ASRM (revised American Society for Reproductive Medicine) classification for all patients 1
• Add Enzian classification for patients with deep endometriosis 1
• Include EFI (Endometriosis Fertility Index) for patients with fertility concerns 1

What NOT to Do

Avoid CT Imaging

• CT (with or without IV contrast) is not recommended for initial imaging evaluation of suspected endometriosis 3, 1

Biomarker Limitations

• Serum CA-125 has limited utility as a diagnostic marker, especially for minimal or mild disease 1

Important Doppler Caveat

• Endometrial implants have limited vascularity; presence of Doppler blood flow in a suspected implant should prompt investigation for neoplasm 1

Clinical Pitfalls

• Preoperative imaging is associated with decreased morbidity and mortality and reduces incomplete surgeries requiring repeat procedures 3
• Expanded protocol TVUS requires special training and is not widely available in the United States 3
• Diagnostic delays are common; empiric therapy without immediate surgical diagnosis is recommended by several gynecologic organizations when clinical suspicion is high 5
• Some forms like "subtle" or microscopic endometriosis remain controversial regarding clinical significance 1