What are the key clinical features that may suggest a diagnosis of Factor V Leiden in a patient presenting with thrombosis?

Key clinical features suggesting Factor V Leiden mutation in a patient presenting with thrombosis include:

• Presentation with unprovoked venous thromboembolism (VTE), such as deep vein thrombosis (DVT) or pulmonary embolism (PE), especially when no recent major clinical risk factors (e.g., surgery, trauma, immobilisation, pregnancy, or hormonal therapy) are identified.
• A personal history of recurrent or early-onset VTE events.
• A family history of VTE in a first-degree relative, which increases suspicion of hereditary thrombophilia including Factor V Leiden mutation.
• Thrombosis occurring at a young age or in unusual sites may also raise suspicion.
• Absence of provoking factors and presence of thrombosis despite standard risk factor management.

Testing for Factor V Leiden mutation (a form of hereditary thrombophilia) is generally considered in people with unprovoked VTE who have a first-degree relative with VTE, as this may influence decisions about the duration of anticoagulation treatment and family risk management.

Routine thrombophilia testing, including for Factor V Leiden, is not recommended in provoked VTE or in people continuing anticoagulation treatment, as it does not usually alter management.

Clinical assessment should include detailed personal and family history of thrombosis and exclusion of other causes.

These features guide clinicians to consider hereditary thrombophilia testing, including Factor V Leiden mutation, in appropriate patients presenting with thrombosis.

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