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D-Dimer

D-dimer — a blood test used to rule out deep vein thrombosis and pulmonary embolism.

A test that measures clot breakdown products, used particularly to rule out venous thromboembolism (DVT, pulmonary embolism) in patients with low to moderate clinical probability.

Indication

  • Ruling out deep vein thrombosis (DVT) in patients with low to moderate clinical probability
  • Ruling out pulmonary embolism in patients with low to moderate clinical probability
  • Diagnosis and monitoring of disseminated intravascular coagulation (DIC)
  • Supportive test in suspected aortic dissection
  • Assessment of thrombosis risk in COVID-19 and severe infections
  • Assessment of recurrence following anticoagulant therapy

Preparation

  • No special fasting is required
  • Pregnancy, postoperative status, or recent trauma should be reported
  • Use of anticoagulants should be reported
  • Recent inflammatory or infectious conditions should be reported

How it's performed

  1. A venous blood sample is drawn from the arm
  2. Measurement is performed on plasma using the immunoturbidimetric method
  3. The result is reported in ng/mL FEU or ng/mL DDU
  4. Interpretation is performed together with the clinical probability score (Wells score)
  5. Age-adjusted threshold (age × 10 ng/mL FEU) may be applied

Post-procedure

  • A negative result has high value in ruling out thromboembolism in patients with low clinical probability
  • A positive result requires further imaging (Doppler ultrasound, CT angiography)
  • Serial measurements may be performed in DIC monitoring
  • Results should be interpreted promptly in the emergency department or clinic

Risks

  • Small bruise or tenderness related to blood draw
  • False positive results (low specificity) in conditions such as surgery, pregnancy, advanced age, cancer, and infection
  • A normal result alone does not rule out thromboembolism in patients with high clinical probability
  • The test result should not be interpreted without a clinical probability score

FAQ

My D-dimer is high, do I have a clot?

Not necessarily. D-dimer rises in many conditions including surgery, pregnancy, infection, and cancer. Confirmation with imaging is required.

If my D-dimer is low, does that mean there is no clot?

In patients with low clinical probability, a negative D-dimer is a strong tool for ruling out venous thromboembolism; however, it is not sufficient on its own in patients with high clinical probability.

How long does the result take?

In most hospitals it is processed urgently and the result is available within 30-60 minutes.