When to resume warfarin (anticoagulant) after surgery in a patient with moderate thromboembolic risk?

Resuming Warfarin After Surgery in Patients with Moderate Thromboembolic Risk

For patients with moderate thromboembolic risk, warfarin should be resumed within 24 hours after surgery (typically the evening of surgery) when adequate hemostasis has been achieved, at the patient's usual maintenance dose. 1

Timing of Warfarin Resumption

• Resume warfarin within 24 hours after surgery (typically the evening of surgery or the next day) when adequate hemostasis has been achieved 1
• Early resumption (within 24 hours) is associated with lower rates of arterial thromboembolism (0.1%) compared to delayed resumption (>24 hours) which has higher rates (2.4%) 1
• Warfarin should be restarted at the patient's usual maintenance dose rather than a doubled dose 1

Important Considerations

• It typically takes 2-3 days for warfarin to achieve a partial anticoagulant effect and 4-8 days for full anticoagulant effect after resumption 1
• Delay warfarin resumption if there is inadequate surgical site hemostasis, anticipated need for additional interventions, or patient inability to take oral medications 1
• For high bleeding risk surgeries, consider waiting longer before resuming warfarin, especially if hemostasis is a concern 1

Bridging Anticoagulation

• For patients with moderate thromboembolic risk, bridging with heparin is generally not required 1
• If bridging is needed (for selected higher-risk patients), wait at least 24 hours after low-to-moderate bleeding risk procedures before starting LMWH bridging 1
• For high bleeding risk procedures, wait 48-72 hours before resuming LMWH bridging therapy 1

Monitoring After Resumption

• Check INR within 5-7 days after warfarin resumption to ensure therapeutic levels are being achieved 2
• More frequent monitoring may be needed for patients with fluctuating INRs or those on medications that might interact with warfarin 2

Special Considerations

• Patients with mechanical heart valves, recent stroke/TIA, or high CHA₂DS₂-VASc scores (≥7) may require more aggressive anticoagulation management including bridging 1
• For dental procedures, continuing warfarin with local hemostatic measures is often preferred over interruption 1
• The perioperative management plan should be clearly communicated to all healthcare providers involved in the patient's care 1

Common Pitfalls to Avoid

• Delaying warfarin resumption unnecessarily increases thrombotic risk 1
• Doubling the dose when resuming warfarin doesn't significantly speed time to therapeutic INR and may increase bleeding risk 1
• Failing to consider patient-specific factors such as prior bleeding history, renal function, and concomitant medications that may affect warfarin metabolism 2
• Not providing patients with clear instructions about when and how to resume their warfarin therapy after discharge 1