Color Flow Score of 1 Does NOT Indicate Malignancy
A color flow score of 1 represents minimal or no blood flow and is actually associated with benign lesions, not malignancy. 1
Understanding the Color Flow Scoring System
The color flow score ranges from 1 to 4 in standardized classification systems like O-RADS (Ovarian-Adnexal Reporting and Data System):
This scoring system is used specifically for adnexal mass characterization on Doppler ultrasound. 1
Why Color Flow Score 1 Suggests Benign Disease
Malignant lesions typically demonstrate neovascularity with strong internal blood flow, corresponding to higher color scores (3-4), not score 1. 1
The key distinguishing features work as follows:
- Benign lesions: Often show no blood flow or minimal flow (color score 1) 1
- Malignant lesions: Demonstrate very strong flow (color score 4) due to tumor neovascularity 1
Clinical Application in Adnexal Mass Evaluation
When evaluating an adnexal mass with color Doppler:
- Absence of vascularity (score 1) helps identify benign solid-appearing components such as clots or debris within cysts 1
- Strong internal vascularity (score 3-4) within solid components raises concern for malignancy and helps differentiate true solid tissue from hemorrhagic debris 1
The IOTA Simple Rules classification system uses a simplified binary approach: "no flow" is a benign feature (B feature), while "very strong flow" is a malignant feature (M feature). 1
Common Pitfall to Avoid
Do not assume that absence of color flow (score 1) completely excludes malignancy—slow flow may be below the detection threshold of the ultrasound machine, and technical factors like gain settings affect visualization. 2 However, the presence of strong flow is far more concerning for malignancy than its absence. 1
When color flow is absent or minimal, use spectral Doppler to distinguish true absence of flow from motion artifacts or flow that is simply too slow to detect. 1, 2