Test guide

D-Dimer

A fibrin degradation product used mainly to help rule out venous thromboembolism when clinical probability is low.

For professionalsReviewed 2026-10-06

What it is for

Supports the exclusion of deep-vein thrombosis and pulmonary embolism in patients with low or intermediate clinical probability, in combination with validated clinical decision rules. A negative result on a validated assay allows clinicians to avoid unnecessary imaging; a positive result is non-specific and triggers imaging.

Limitations

D-dimer rises with age, pregnancy, recent surgery, infection, inflammation, and malignancy — specificity is low and a positive result alone does not diagnose thrombosis. Age-adjusted cutoffs apply to specific populations. Units differ between assays (FEU vs DDU) and are not interchangeable.

Before you test

No specific preparation is needed. Recent surgery, injury, pregnancy, or active infection should be reported as they raise values.

Health information only. This guide does not diagnose or replace advice from a healthcare professional.

Also known as

  • fibrin degradation fragment
  • DD

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