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Textbook/Haematology and transfusion/Inherited thrombophilia/Rapid
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Inherited thrombophilia

Essential points for quick revision.

2 min synopsisUK scopeSources checked 27 Aug 2026Clinical review pending
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Acute thrombosis takes priority over testing

Suspected proximal DVT, pulmonary embolism, cerebral or splanchnic thrombosis, neonatal purpura fulminans or extensive skin necrosis requires immediate disease-specific treatment; a thrombophilia panel must not delay it.

Action: Use the acute VTE or organ-thrombosis pathway, obtain routine baseline bloods and selected pre-anticoagulation samples only if this causes no delay, start therapeutic anticoagulation when safe, involve haematology for unusual-site, recurrent, paediatric or severe natural-anticoagulant deficiency phenotypes, and defer interference-prone protein assays until a valid result would change management.

Synopsis

Select inherited thrombophilia testing only when it can change care, interpret assays at a valid time, and base anticoagulation, family and pregnancy decisions on the whole recurrence risk rather than a genetic label alone.

  • Do not order hereditary thrombophilia testing after a clearly provoked VTE or while a patient will continue anticoagulation regardless of the result; test only when a defined result can change care.
  • NICE advises considering hereditary testing after unprovoked VTE when a first-degree relative has DVT or PE and stopping anticoagulation is being considered; consider APS testing separately.
  • Core inherited defects are factor V Leiden, prothrombin G20210A and antithrombin, protein C and protein S deficiency; MTHFR variants and homocysteine panels are not routine thrombophilia tests.

Key red flags

Shock, syncope, severe hypoxaemia, chest pain or cardiac arrest with suspected PE requires immediate resuscitation and reperfusion assessment rather than hereditary testing.

Warfarin skin necrosis

Painful retiform skin necrosis shortly after VKA initiation can reflect rapid protein C decline and needs urgent treatment review.

Investigation priorities

01
First-line: define the testing decisionFirst stepFirst line

Establish whether a result will alter anticoagulant duration, pregnancy, oestrogen or relative counselling.

Management branches

Acute VTETreat first and preserve only useful samples

DVT, PE or unusual venous thrombosis is suspected or confirmed.

  1. Start the site-specific diagnostic and therapeutic anticoagulation pathway; do not postpone treatment for thrombophilia blood sampling.
  2. Document provoking factors, family history, pregnancy, oestrogen, cancer and prior events and obtain routine organ and bleeding baseline.

Key medicines

Apixaban for suitable acute VTEGive 10 mg orally twice daily for 7 days, then 5 mg twice daily for at least the remainder of the first 3 months; if extended prevention is chosen after 6 months, use 2.5 mg twice daily when clinically appropriate.
WarfarinInitiate with therapeutic LMWH or UFH and overlap for at least 5 days and until INR is at least 2.0 on the locally defined confirmation schedule; maintain a usual VTE INR target of 2.0–3.0.
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Sources and review status4 sources · checked 27 Aug 2026 · clinical review pending
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

Authoring stateRapid draftClinical stateAwaiting reviewJurisdictionUnited Kingdom