What Is D-Dimer?

What it is

D-dimer is a fibrin-degradation product — a protein fragment produced when a blood clot is broken down.

Why it matters

A negative D-dimer helps rule out venous thromboembolism (VTE) in low-risk patients; a positive result is non-specific.

Specimen

Whole blood / plasma

Interpretation

Negative = VTE unlikely (high negative predictive value). Positive = non-specific, needs imaging.

Limitations

Positive result is non-specific (surgery, pregnancy, inflammation); used for VTE exclusion, not diagnosis.

Related test: D-Dimer Rapid Test — specimen: WB / P