What are the diagnostic criteria and imaging modalities for uterine adenomyosis on Ultrasound (USG)?

Diagnostic Criteria and Imaging Modalities for Uterine Adenomyosis on Ultrasound

Transvaginal ultrasound (TVUS) is the first-line imaging modality for diagnosing adenomyosis with a pooled sensitivity of 82.5% and specificity of 84.6%, though its accuracy decreases significantly when coexisting with fibroids. 1

Key Ultrasound Diagnostic Criteria for Adenomyosis

Primary Sonographic Features

• Heterogeneous myometrium - highest sensitivity (86.0%) 2
• Globular uterine enlargement - highest specificity (78.1%) 2
• Myometrial cysts - fluid-filled spaces within the myometrium 3
• Asymmetrical myometrial wall thickening 4
• Ill-defined endometrial-myometrial junction/interface 5
• Echogenic linear striations - radiating from endometrium into myometrium 3
• "Venetian blind" shadowing - thin acoustic shadows from muscular hypertrophy 3

Additional Ultrasound Findings

• "Question mark" sign - improves sensitivity to 92% and specificity to 88% when combined with other features 2
• Subendometrial echogenic nodules - representing ectopic endometrial tissue 3
• Blurred endometrial border - due to invasion of endometrial tissue 3

Optimal Ultrasound Technique

Combined Approach

• Transabdominal + transvaginal ultrasound should be used together for optimal assessment 1
• Transabdominal approach is particularly helpful for:
  • Significantly enlarged uterus
  • Poor visualization on TVUS due to position
  • When TVUS is uncomfortable or inappropriate 1

Enhanced Ultrasound Techniques

• Color/Power Doppler evaluation - shows increased vascularity with a pattern of penetrating vessels 3

  • Helps differentiate adenomyosis from fibroids (sensitivity 95.6%, specificity 93.4%) 2
  • Lower resistive index (<0.7) and pulsatility index (<1.2) are characteristic 1

• 3D Ultrasound - allows multiplanar imaging and surface rendering 1

  • Poor definition of junctional zone shows highest sensitivity (86%) 2
  • No significant improvement in overall accuracy compared to 2D TVUS 2

• Elastography - measures tissue strain 1

  • Improves specificity (82.9% vs 63.9%) while maintaining comparable sensitivity 2
  • Adenomyosis appears as brighter irregular lesions (vs. fibroids which appear as dark areas) 1

• Sonohysterography - can help when focal endometrial abnormalities are present 1

  • Ectopic glands frequently fill with air or fluid during the procedure 3

Diagnostic Challenges and Pitfalls

Coexisting Conditions

• Presence of fibroids significantly reduces sensitivity of TVUS for adenomyosis:
  • With fibroids: sensitivity 33.3%, specificity 78%
  • Without fibroids: sensitivity 97.8%, specificity 97.1% 1

Differential Diagnosis

• Leiomyomas - well-defined borders vs. ill-defined borders of adenomyosis 3
• Uterine contractions - transient nature distinguishes from adenomyosis 3
• Neoplasms - different enhancement patterns on Doppler 3

When to Consider MRI

• When TVUS findings are inconclusive 6
• When coexisting with fibroids or severe endometriosis 6
• For treatment planning 4
• MRI offers higher specificity and positive predictive value 7
• MRI sensitivity approximately 78% and specificity nearly 93% for adenomyosis 1

Best Combination of Ultrasound Features

• Dual combination with highest accuracy: "bulky uterus" + "ill-defined endometrial-myometrial interface" (sensitivity 39%, specificity 91%) 5
• Triple combination with highest accuracy: "bulky uterus" + "heterogeneous myometrium" + "ill-defined endometrial-myometrial interface" (sensitivity 38%, specificity 93%) 5

Practical Approach to Diagnosis

1. Start with combined transabdominal and transvaginal ultrasound
2. Look for multiple diagnostic features, particularly heterogeneous myometrium and globular uterus
3. Add color Doppler to assess vascularity patterns
4. Consider 3D ultrasound or elastography if available
5. If findings are inconclusive or fibroids are present, proceed to MRI