When and for how long should warfarin (anticoagulant) be held prior to a thyroidectomy?

Perioperative Management of Warfarin for Thyroidectomy

For patients on warfarin requiring thyroidectomy, warfarin should be stopped 5 days before surgery and resumed 12-24 hours postoperatively when hemostasis is adequate.

Preoperative Management

When to Stop Warfarin

• Stop warfarin 5 days before thyroidectomy 1
  • This timeframe allows for normalization of INR by the day of surgery
  • Studies show only 7% of patients will have INR >1.5 on the day of surgery when warfarin is stopped 5 days prior 2
  • Warfarin's half-life is 36-42 hours, requiring approximately 5 half-lives for elimination of anticoagulant effect 1

INR Monitoring

• Check INR 1-2 days before surgery to ensure adequate normalization 2
• Target INR for safe thyroidectomy:
  • INR ≤1.5 is considered safe to proceed with most surgeries 2
  • If INR >1.5 but <2.0 one day before surgery, observation may be sufficient 2
  • If INR >2.0 one day before surgery, consider low-dose vitamin K (1 mg oral or IV) 2

Bridging Anticoagulation

Bridging decision depends on thromboembolism risk:

• High thromboembolism risk patients (mechanical heart valve, atrial fibrillation with CHADS₂ score ≥4, recent VTE within 3 months):

  • Consider bridging with therapeutic-dose LMWH 1, 2
  • Last dose of therapeutic LMWH should be given 24 hours before surgery 1

• Low thromboembolism risk patients:

  • No bridging anticoagulation recommended 1

Postoperative Management

When to Resume Warfarin

• Resume warfarin 12-24 hours after surgery (evening of surgery or next morning) 1, 2
• Use the patient's usual maintenance dose rather than a loading dose 2
• It typically takes 4-5 days to reach therapeutic INR after resuming warfarin 2

Postoperative Bridging

For patients who required preoperative bridging:

• For thyroidectomy (moderate bleeding risk procedure):
  • Resume therapeutic-dose LMWH 24-48 hours after surgery when hemostasis is adequate 1, 2
  • Continue LMWH until INR reaches ≥2.0 2

Postoperative Monitoring

• Check INR on day 4 post-procedure 2
• Discontinue LMWH when INR >1.9 2
• Recheck INR 7-10 days post-procedure 2

Common Pitfalls to Avoid

1. Inadequate preoperative planning: Failing to stop warfarin 5 days before surgery can lead to elevated INR and surgical cancellation or increased bleeding risk 1, 3

2. Insufficient INR monitoring: Not checking INR 1-2 days before surgery can lead to unexpected elevated INR values on the day of surgery 2

3. Inappropriate bridging: Providing bridging anticoagulation for low-risk patients increases bleeding risk without significant thrombotic benefit 1

4. Delayed warfarin resumption: Unnecessarily delaying warfarin resumption can increase thromboembolism risk 2

5. Overuse of vitamin K: Routine administration of vitamin K is not recommended as it can lead to warfarin resistance postoperatively 2

6. Baseline INR influence: Higher baseline INR values (>3.0) are associated with slower normalization after stopping warfarin 4, which may require earlier discontinuation or vitamin K administration

By following this protocol, patients on warfarin requiring thyroidectomy can be managed safely with minimal risk of both thrombotic and hemorrhagic complications.