Revised MUSA 2022 Guidelines for Adenomyosis Diagnosis
Core Diagnostic Framework
The 2022 MUSA consensus divides ultrasound features of adenomyosis into direct features (indicating ectopic endometrial tissue in myometrium) and indirect features (reflecting secondary myometrial changes), with at least one direct feature now considered essential for definitive diagnosis. 1
Direct Features (Pathognomonic for Adenomyosis)
The following features indicate actual presence of endometrial tissue within the myometrium and are mandatory for diagnosis 1:
- Myometrial cysts: Anechoic or hypoechoic round areas within the myometrium 1
- Hyperechogenic islands: Echogenic areas within the myometrium representing ectopic endometrial tissue 1
- Echogenic subendometrial lines and buds: Linear or nodular echogenic structures in the subendometrial region 1
Indirect Features (Secondary Changes)
These features reflect myometrial response to adenomyosis but are insufficient alone for diagnosis 1:
- Globular uterus: Enlarged, rounded uterine configuration 1
- Asymmetrical myometrial thickening: Uneven myometrial wall thickness 1
- Fan-shaped shadowing: Acoustic shadowing radiating from the endometrium 1
- Translesional vascularity: Blood flow through affected myometrium 1
- Irregular junctional zone: Poorly defined endometrial-myometrial interface 1
- Interrupted junctional zone: Focal breaks in the junctional zone 1
Critical Imaging Recommendations
Three-Dimensional Ultrasound Integration
3D ultrasound is strongly recommended to optimize visualization of the junctional zone, as direct features may be visible only on 3D imaging in approximately 50% of cases with adenomyosis. 1, 2
- In subfertile women scheduled for ART, direct features were visible only at 3D TVUS in 50.5% of women with adenomyosis 2
- 3D imaging significantly improves detection of direct features that may be missed on 2D alone 1, 2
Diagnostic Performance
Transvaginal ultrasound using MUSA criteria demonstrates pooled sensitivity of 82.5% and specificity of 84.6% for adenomyosis diagnosis 3. When at least one direct feature is present, diagnostic confidence is substantially higher 1.
Important Clinical Caveats
The 16% False Negative Problem
In symptomatic patients, approximately 16% may not demonstrate any direct ultrasound signs despite having clinical adenomyosis, potentially creating false negatives with strict application of the 2022 criteria. 4
- No statistically significant difference exists in symptom severity between patients with and without direct ultrasound signs 4
- In symptomatic populations where other causes have been excluded, adenomyosis remains highly probable even without direct signs 4
- Clinical context must be integrated with imaging findings to avoid underdiagnosis 4
MRI as Complementary Modality
When ultrasound is inconclusive or adenomyosis obscures endometrial visualization, MRI should be considered 5, 3:
- MRI can display the endometrium even when obscured by adenomyosis on ultrasound 3
- Junctional zone thickening and T2 hyperintense foci are characteristic MRI findings 6
- MRI demonstrates 78-88% sensitivity and 67-93% specificity for adenomyosis 6
Practical Diagnostic Algorithm
Perform systematic 2D and 3D transvaginal ultrasound examining for all MUSA features 1, 2
Identify presence of direct features (myometrial cysts, hyperechogenic islands, or subendometrial lines/buds) 1
If at least one direct feature is present: Diagnosis of adenomyosis is confirmed 1
If only indirect features present:
Document all features systematically using standardized MUSA terminology 1
Association with Endometriosis
Direct features of adenomyosis are significantly more common in women with endometriosis (OR 2.8,95% CI 1.8-4.3), warranting careful evaluation for coexistent disease 2.