How is endometriosis diagnosed?

How Endometriosis is Diagnosed

Endometriosis is diagnosed clinically based on characteristic symptoms (dysmenorrhea, dyspareunia, dyschezia, chronic pelvic pain) combined with imaging—surgical confirmation is no longer required before initiating treatment. 1

Initial Clinical Assessment

The diagnosis begins with identifying specific pain patterns and physical examination findings:

• Pain patterns to identify: dysmenorrhea, dyspareunia (painful intercourse), dyschezia (painful defecation), dysuria (painful urination), or chronic pelvic pain 1
• Infertility is present in approximately 50% of patients with endometriosis 1
• Physical examination findings: Look for nodularity on pelvic exam, fixed retroverted uterus, or tender uterosacral ligaments 1

Critical point: The severity of pain correlates poorly with disease stage—minimal disease can cause severe symptoms and vice versa 2, 3

First-Line Imaging: Transvaginal Ultrasound

Transvaginal ultrasound (TVUS) is the recommended initial imaging modality 4, 1:

• Standard TVUS has 82.5% sensitivity and 84.6% specificity for endometriosis 1, 5
• However, standard TVUS alone is insufficient for deep endometriosis—you must use expanded protocol TVUS 1

Expanded Protocol TVUS Requirements

The expanded protocol requires specialized training and must include 1:

• Evaluation of uterosacral ligaments
• Assessment of anterior rectosigmoid wall
• Dynamic sliding maneuvers to assess mobility
• Bowel preparation or enema prior to examination
• Evaluation of appendix and diaphragm

Adding transabdominal ultrasound to TVUS widens the field of view to evaluate urinary tract involvement (ureters, bladder) and bowel involvement beyond the pelvis (appendix, terminal ileum, cecum, sigmoid) 4, 1

When to Use MRI

MRI pelvis is equally appropriate as first-line imaging or should be used when TVUS is inconclusive 4, 1:

MRI Performance by Location 4, 1:

• Intestinal endometriosis: 92.4% sensitivity, 94.6% specificity
• Deep infiltrating endometriosis (uterosacral ligament, retrocervical, rectovaginal septum): 88% sensitivity, 83.3% specificity
• Bladder wall endometriosis: 50% sensitivity, 97.3% specificity

MRI Protocol Considerations

MRI without IV contrast is sufficient for detecting deep endometriosis 4, 1. However, MRI with IV contrast is highly recommended to differentiate endometriomas from ovarian malignancies, as patients with endometriosis are at increased risk for endometriosis-associated malignancies 4, 1

Key MRI findings include 1:

• Endometriomas with T2 dark spot sign
• T2 hypointense fibrosis at torus uterinus and uterosacral ligaments
• Obliteration of pouch of Douglas
• T1 hyperintense hemorrhagic foci

Technical optimization: Use moderate bladder distention and vaginal contrast to improve lesion conspicuity 1

What NOT to Use

CT pelvis has no role in standard endometriosis diagnosis—there is no relevant literature supporting its use for initial or follow-up imaging 4, 1

Laboratory Testing

CA-125 has no clinical utility for diagnosis 1. It may be helpful for monitoring clinical response in patients with confirmed extrauterine disease, but can be falsely elevated due to peritoneal inflammation or infection 1

Role of Surgery

Laparoscopy with histologic confirmation is no longer required before initiating empiric treatment 1. Surgery is now reserved for:

• Definitive treatment rather than diagnosis 1
• Cases requiring bowel or urologic surgery for deep infiltrating disease 1

The imaging-first approach reduces morbidity by enabling better surgical planning and decreasing incomplete surgeries that require reoperation 1

Critical Pitfalls to Avoid

• Do not rely on standard TVUS alone for deep endometriosis—expanded protocols or MRI are essential 1
• Do not assume negative imaging excludes endometriosis—superficial peritoneal disease is poorly detected by all imaging modalities 4, 1
• Do not delay empiric treatment waiting for surgical confirmation—clinical diagnosis is sufficient to begin therapy 1
• Do not use CT pelvis as it provides no diagnostic value for endometriosis 4, 1

Diagnostic Algorithm Summary

1. Clinical assessment: Identify characteristic pain patterns and physical exam findings 1
2. First-line imaging: Expanded protocol TVUS (with or without transabdominal US) OR MRI pelvis 4, 1
3. MRI for surgical planning: Use when deep infiltrating disease is suspected or TVUS is inconclusive 1
4. Initiate empiric treatment: Based on clinical diagnosis and imaging—do not wait for surgical confirmation 1
5. Reserve surgery: For definitive treatment or when bowel/urologic involvement requires surgical intervention 1