Medications
Warfarin (Coumadin) Before Surgery
Warfarin is a blood thinner that needs careful timing before surgery, and some people need 'bridging' to stay protected from clots.
Quick answer
Why it matters
Warfarin keeps your blood from clotting. Surgery on fully-thinned blood risks serious bleeding, so it's usually paused: but it takes several days for its effect to wear off, which is why the INR is checked.
People with a mechanical heart valve, a recent clot, or high-risk atrial fibrillation can form a dangerous clot during the gap, so they may be 'bridged' with heparin or low-molecular-weight heparin until just before surgery.
Do not stop without instruction
What to ask your doctor
- Which day do I stop warfarin, and do I need an INR check?
- Do I need bridging injections. And how do I use them?
- When do I restart warfarin after surgery?
- What is my target INR for surgery?
Red flags, call your team
Red flags, call your team
- You have a mechanical heart valve
- You had a recent blood clot (DVT, PE) or stroke
- Unusual bleeding or bruising before surgery
References
- American Society of Regional Anesthesia and Pain Medicine (ASRA). Anticoagulation guidance (warfarin ~5 days + normalized INR). asra.com
- American College of Cardiology / American Heart Association (ACC/AHA), perioperative anticoagulation. acc.org
Frequently asked questions
How many days before surgery do I stop warfarin?
Usually about 5 days, with an INR check before surgery. Follow your team's exact plan, as some patients need bridging.
What is bridging?
Bridging means using short-acting heparin injections while warfarin is paused, to keep high-risk patients protected from clots until just before surgery.