D-dimer testing is of clinical use when there is a suspicion of deep venous thrombosis (DVT) or pulmonary embolism (PE) or disseminated intravascular coagulation (DIC). Most situations require a risk assessment score e.g. Wells score for DVT, Wells score for PE.
- D-dimer are NOT indicated in patients with a moderate or high score (DVT or PE) as the result will not alter the need for further imaging(Doppler, CT pulmonary angiogram etc.)
- D-dimers are NOT indicated in patients whose clinical presentation is unrelated to DVT, PE or DIC.
- D-dimers ARE most useful for patients with a low probability of DVT or PE, where a negative result makes it unlikely that they have DVT or PE.
Can be due to:
- liver disease
- high rheumatoid factor
- recent surgery
- advanced age
- False negative readings can occur if the sample is taken either too early after thrombus formation
- If testing is delayed for several days.
- Additionally, the presence of anti-coagulation can render the test negative because it prevents thrombus extension.