When to hold warfarin (International Normalized Ratio (INR) anticoagulant) before thyroidectomy and when to restart it post-operatively?

Perioperative Warfarin Management for Thyroidectomy

Warfarin should be stopped 5 days before thyroidectomy and resumed 12-24 hours after surgery when adequate hemostasis is achieved. 1, 2

Preoperative Management

When to Hold Warfarin

• Stop warfarin 5 days before thyroidectomy 2, 1
• This timing allows for normalization of INR by the day of surgery, as warfarin's half-life is 36-42 hours 2
• Check INR 1-2 days before surgery to ensure it's ≤1.5, which is considered safe for most surgeries 1
• If INR >1.5 one day before surgery:
  • For INR 1.5-1.8: May proceed with surgery if bleeding risk is low 1
  • For INR >2.0: Consider postponing surgery or administering low-dose vitamin K (1-2.5 mg) 1

Bridging Anticoagulation

Bridging decisions should be based on thrombotic risk:

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

   • Use therapeutic-dose LMWH starting 36 hours after the last warfarin dose 2, 1
   • Administer last dose of LMWH at least 24 hours before surgery 2

2. Low thrombotic risk patients:

   • No bridging anticoagulation needed 2, 1

Postoperative Management

When to Restart Warfarin

• Resume warfarin 12-24 hours after surgery (evening of surgery or next morning) 2, 1
• Use the patient's usual maintenance dose rather than a loading dose 2, 1, 3
• It typically takes 4-5 days to reach therapeutic INR after resuming warfarin 1

Bridging After Surgery

For patients who required preoperative bridging:

1. Low bleeding risk procedures:

   • Resume LMWH at therapeutic dose 24 hours post-procedure 1
   • Continue LMWH until INR reaches ≥2.0 1

2. High bleeding risk procedures (including thyroidectomy):

   • Wait 48-72 hours before restarting therapeutic LMWH 2, 1
   • Consider prophylactic LMWH initially (starting 12 hours post-procedure) 1
   • Check INR on day 4 post-procedure 1
   • Discontinue LMWH when INR >1.9 1
   • Recheck INR 7-10 days post-procedure 1

Important Considerations and Pitfalls

1. Bleeding Risk:

   • Despite stopping warfarin 5 days before surgery and normalizing INR, patients may still have increased intraoperative blood loss compared to patients not on chronic anticoagulation 4
   • Thyroidectomy is considered a high bleeding risk procedure due to its vascularity and proximity to vital structures

2. Monitoring:

   • Only 7% of patients will have INR >1.5 on the day of surgery when warfarin is stopped 5 days prior 1
   • Ensure INR is checked before surgery to confirm it's ≤1.5 2
   • The FDA label for warfarin recommends PT/INR determination just prior to any surgical procedure 3

3. Common Errors to Avoid:

   • Failing to stop warfarin early enough (5 days before surgery)
   • Providing bridging anticoagulation for low-risk patients, which increases bleeding risk without significant thrombotic benefit
   • Restarting anticoagulation too early after surgery, which can lead to significant bleeding complications
   • Delaying anticoagulant resumption unnecessarily, which can lead to higher thromboembolism rates
   • Doubling the warfarin dose post-operatively, which is not recommended by current guidelines 1, 3

By following this algorithm for perioperative warfarin management in thyroidectomy patients, you can minimize both bleeding and thrombotic complications while ensuring optimal patient outcomes.