A summary of anticoagulants (ED focus)
This concise reference describes commonly used systemic anticoagulants, how they affect routine tests, immediate priorities in the bleeding patient, licensed reversal options in the UK and pragmatic alternatives when agents are unavailable. Recommendations and operational points reflect NICE, MHRA and RCEM/NPIS guidance; always follow local formulary and haematology advice.
Why this matters
- Anticoagulants are widely used (AF, VTE, thromboprophylaxis). Life‑threatening bleeding requires rapid identification of the agent, prompt haemorrhage control and the correct reversal strategy.
- Routine coagulation tests may be normal despite clinically significant direct oral anticoagulant (DOAC) effect - do not assume a normal INR/aPTT excludes DOACs.
Drug classes, examples and targets
How anticoagulants affect routine tests - practical caveats
- Warfarin: prolongs PT/INR - INR guides reversal decisions.
- Dabigatran: prolonged thrombin time (TT) and often aPTT; a normal TT effectively excludes clinically relevant dabigatran effect.
- Factor Xa inhibitors: PT and aPTT are variably affected and can be normal despite clinically relevant drug levels.
- Anti‑factor Xa assays, calibrated for a specific DOAC, can quantify apixaban/rivaroxaban/edoxaban when available; however:
- these assays are not universally available and require appropriate calibration,
- NICE/MHRA caution against relying on these assays alone to guide reversal or to judge antidote efficacy; clinical assessment is paramount.
- Do not delay haemorrhage control while awaiting specialised assays.