Perioperative Management of Warfarin (Coumadin) Therapy
Warfarin should be stopped 5 days before elective surgery and bridging anticoagulation should be provided based on thromboembolic risk assessment. 1
Preoperative Management
When to Stop Warfarin
- Stop warfarin approximately 5 days before surgery to allow normalization of INR (target INR ≤1.5) 1
- For elderly patients or those with high-intensity INR targets (3.0-4.0), a longer interruption period may be necessary 1
- Check INR the day before surgery; if INR >1.8, consider administering low-dose oral vitamin K (1-2.5 mg) for reversal 1
- Surgery can proceed safely when INR ≤1.5 1, 2
Risk Assessment for Bridging
Assess thromboembolic risk to determine need for bridging anticoagulation:
High Thromboembolic Risk (bridging recommended) 1:
- Mechanical mitral valve
- Recent VTE (within 3 months)
- Atrial fibrillation with CHADS₂ score ≥5
- Antiphospholipid syndrome with recurrent thrombosis
Moderate Thromboembolic Risk (consider bridging) 1:
- Bileaflet aortic valve with additional risk factors
- Atrial fibrillation with CHADS₂ score 3-4
- VTE within 3-12 months
Low Thromboembolic Risk (no bridging needed) 1:
- Bileaflet aortic valve without risk factors
- Atrial fibrillation with CHADS₂ score 0-2
- VTE >12 months ago
Bridging Protocol
When Bridging is Indicated
- Start LMWH 36 hours after last warfarin dose (approximately day 3 before surgery) 1
- Use therapeutic or intermediate dose LMWH based on patient risk 1
- Administer last preoperative dose of LMWH 24 hours before surgery at half the total daily dose 1
- Check INR before procedure; proceed if INR ≤1.5 1
Postoperative Management
For high bleeding risk procedures 1:
- Resume warfarin within 12-24 hours after surgery (evening of or next morning) at maintenance dose
- Delay LMWH resumption for 48-72 hours after surgery
- Consider prophylactic or intermediate LMWH doses initially
- For very high bleeding risk procedures (neurosurgical, cardiovascular), consider mechanical prophylaxis instead of pharmacological
For low bleeding risk procedures 1:
- Resume warfarin within 12-24 hours after surgery
- Restart LMWH at previous dose within 24 hours after surgery
- Continue LMWH until INR reaches therapeutic range (usually 5-7 days)
- Check INR on day 4-5; discontinue LMWH when INR >1.9
Special Considerations
Minor Procedures
- For minor dental, skin, or eye procedures with low bleeding risk, warfarin may not need to be interrupted 1, 2
- For procedures with minimal bleeding risk, consider maintaining INR at the lower end of the therapeutic range 3
Urgent Surgery
- For urgent procedures requiring immediate reversal, prothrombin complex concentrates (PCC) are preferred over fresh frozen plasma 2
- Vitamin K₁ is essential for sustaining the reversal achieved by PCC or FFP 2
Monitoring
- Check INR the day before surgery to ensure adequate reversal 1
- Monitor INR regularly after restarting warfarin until stable therapeutic levels are achieved 3
- An increase in INR >0.4 units correlates with the need to decrease the warfarin dose 4
Common Pitfalls and Caveats
- Inadequate warfarin interruption: Failing to stop warfarin 5 days before surgery may result in elevated INR and increased bleeding risk 1
- Resuming full-dose LMWH too early: Major bleeding rates up to 20% have been reported when treatment-dose LMWH is given too soon after high bleeding risk procedures 1
- Delayed warfarin resumption: Delaying warfarin restart beyond 24 hours after surgery may prolong the need for bridging therapy 1
- Overlooking INR testing: Failure to check INR before surgery may lead to proceeding with surgery despite suboptimal coagulation status 1
- Inappropriate bridging decisions: Both over-bridging low-risk patients and under-bridging high-risk patients can lead to adverse outcomes 1