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1. The 5 Benign Features (B-Features)
If one or more B-features are present in the absence of M-features, the lesion is classified as benign:
B1: Unilocular cyst (no internal septa or solid components).
B2: Presence of solid components with largest diameter < 7 mm.
B3: Presence of acoustic shadows (common in fibromas, dermoid cysts).
B4: Smooth multilocular tumor with largest diameter < 100 mm.
B5: No blood flow on color Doppler (Color Score 1).
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2. The 5 Malignant Features (M-Features)
If one or more M-features are present in the absence of B-features, the lesion is classified as malignant:
M1: Irregular solid tumor.
M2: Presence of ascites.
M3: At least four papillary projections.
M4: Irregular multilocular-solid tumor with largest diameter ≥ 100 mm.
M5: Very strong blood flow on color Doppler (Color Score 4).
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3. Inconclusive Results & IOTA ADNEX Model
When both B and M features are present, or when neither is present (occurring in ~10% of cases), the lesion is inconclusive. The sonographer should use the IOTA ADNEX model to calculate precise probabilities of stage-specific malignancy.
ADNEX utilizes patient age, CA-125, maximum lesion diameter, proportion of solid tissue, and number of papillary projections.
Enables risk stratification into Stage I, Stage II–IV ovarian cancer, or secondary metastatic neoplasms.