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==Background==
==Background==
*Also known as Factor V Leiden Deficiency or FVL
*Most common inherited thrombophilia (3-8% of Caucasians)
*Point mutation in FV making it resistant to cleavage by activated protein C
*Point mutation in Factor V making it resistant to cleavage by activated protein C → hypercoagulable state
*Increased risk of thrombosis
*Heterozygous: 3-8× increased risk of VTE; Homozygous: 50-80× increased risk
*Most individuals with FVL will never have a venous thromboembolism (VTE)
*Most individuals with FVL will never develop a [[DVT|venous thromboembolism (VTE)]]
*'''EM relevance:''' Presents when a provoking factor (OCP use, surgery, immobilization, pregnancy) unmasks the predisposition


==Clinical Features==
==Clinical Features==
*Family history of thrombophilia
*[[DVT]], [[pulmonary embolism]]
*VTE at a young age
*VTE at young age (<50 years) without clear provoking factor
*VTE in an atypical location
*VTE in atypical locations (mesenteric, cerebral venous sinus)
*Recurrent VTE
*Family history of VTE or known thrombophilia


==Differential Diagnosis==
==Differential Diagnosis==
 
{{Increased clotting DDX}}


==Evaluation==
==Evaluation==
===Workup===
*Activated protein C resistance assay — screening test
 
*Factor V Leiden genetic testing — confirmatory
===Diagnosis===
*'''Do NOT order thrombophilia workup in the acute ED setting''' — anticoagulation and acute illness affect results
*Thrombophilia testing should be deferred to outpatient hematology follow-up


==Management==
==Management==
 
*'''Acute VTE:''' Standard anticoagulation per [[DVT]] or [[pulmonary embolism]] guidelines (same as non-FVL patients)
*'''Duration of anticoagulation''' (hematology decision):
**First provoked VTE: 3-6 months
**Unprovoked VTE or recurrent VTE: consider indefinite anticoagulation
*Asymptomatic FVL carriers: no prophylactic anticoagulation; counsel on risk reduction


==Disposition==
==Disposition==
 
*Per underlying VTE management
*Ensure hematology follow-up for thrombophilia evaluation after acute treatment


==See Also==
==See Also==
 
*[[DVT]]
 
*[[Pulmonary embolism]]
==External Links==
*[[Coagulopathy (Main)]]
 


==References==
==References==
<references/>
<references/>


[[Category:HematologyandOncology]]
[[Category:Heme/Onc]]
[[Category:Labs]]

Revisión actual - 06:44 22 mar 2026

Background

  • Most common inherited thrombophilia (3-8% of Caucasians)
  • Point mutation in Factor V making it resistant to cleavage by activated protein C → hypercoagulable state
  • Heterozygous: 3-8× increased risk of VTE; Homozygous: 50-80× increased risk
  • Most individuals with FVL will never develop a venous thromboembolism (VTE)
  • EM relevance: Presents when a provoking factor (OCP use, surgery, immobilization, pregnancy) unmasks the predisposition

Clinical Features

  • DVT, pulmonary embolism
  • VTE at young age (<50 years) without clear provoking factor
  • VTE in atypical locations (mesenteric, cerebral venous sinus)
  • Recurrent VTE
  • Family history of VTE or known thrombophilia

Differential Diagnosis

Evaluation

  • Activated protein C resistance assay — screening test
  • Factor V Leiden genetic testing — confirmatory
  • Do NOT order thrombophilia workup in the acute ED setting — anticoagulation and acute illness affect results
  • Thrombophilia testing should be deferred to outpatient hematology follow-up

Management

  • Acute VTE: Standard anticoagulation per DVT or pulmonary embolism guidelines (same as non-FVL patients)
  • Duration of anticoagulation (hematology decision):
    • First provoked VTE: 3-6 months
    • Unprovoked VTE or recurrent VTE: consider indefinite anticoagulation
  • Asymptomatic FVL carriers: no prophylactic anticoagulation; counsel on risk reduction

Disposition

  • Per underlying VTE management
  • Ensure hematology follow-up for thrombophilia evaluation after acute treatment

See Also

References