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
Frequently Asked Questions
What does a negative D-dimer mean? It makes venous thromboembolism unlikely (high negative predictive value); a positive is non-specific.
Related knowledge
References
- Wells PS et al. Evaluation of D-dimer in the diagnosis of suspected deep-vein thrombosis. N Engl J Med. 2003.
Last reviewed: 2026-09-12