What is the recommended peri‑operative anticoagulation management for a 56‑year‑old woman with atrial fibrillation on chronic warfarin (INR 2.3) scheduled for thyroidectomy in three weeks?

Perioperative Anticoagulation Management for Thyroidectomy

For this 56-year-old woman on warfarin for atrial fibrillation undergoing thyroidectomy in three weeks, stop warfarin 5 days before surgery, check INR the day before to confirm it is ≤1.4-1.5, and do NOT use bridging anticoagulation because she does not have high thromboembolic risk. 1

Risk Stratification

Thromboembolic Risk Assessment

• Calculate the CHA₂DS₂-VASc score to determine stroke risk: this patient likely has a score of 1-2 (age 56 years = 0 points, female sex = 1 point, plus any additional risk factors such as hypertension or diabetes) 1
• Bridging anticoagulation is NOT recommended for patients with atrial fibrillation who have low-to-moderate thromboembolic risk (CHA₂DS₂-VASc ≤4) and no mechanical heart valve 1
• High-risk patients requiring bridging include those with mechanical heart valves, recent stroke/TIA (within 3 months), or CHA₂DS₂-VASc score ≥5 with additional transient risk factors 1

Surgical Bleeding Risk

• Thyroidectomy is classified as a procedure with substantial bleeding risk, requiring interruption of anticoagulation 1
• The target INR for safe surgery is <1.5, ideally <1.4 1, 2

Preoperative Management Timeline

Three Weeks Before Surgery

• Continue warfarin at the current therapeutic dose until 5 days before the procedure 1
• The current INR of 2.3 is therapeutic (target range 2.0-3.0 for atrial fibrillation) and requires no adjustment at this time 1

Five Days Before Surgery

• Stop warfarin completely to allow INR to fall naturally to <1.5 1
• Warfarin discontinuation 5 days preoperatively is the standard approach because warfarin's anticoagulant effect persists for 4-5 days after the last dose 1

One Day Before Surgery

• Check INR to confirm it is ≤1.4-1.5; if the INR meets this target, proceed with surgery as planned 1
• If INR remains >1.5 the day before surgery, consider administering oral vitamin K 1-2 mg, though routine preoperative vitamin K is generally not advised due to potential warfarin resistance postoperatively 2

Bridging Decision: NOT Indicated

This patient does NOT require bridging anticoagulation with heparin or low-molecular-weight heparin because:

• She has atrial fibrillation without a mechanical heart valve 1
• Her thromboembolic risk is low-to-moderate based on age and sex alone (CHA₂DS₂-VASc likely 1-2) 1
• The BRIDGE trial and subsequent guidelines demonstrate that bridging in low-to-moderate risk AF patients increases bleeding without reducing thromboembolism 1
• Bridging is only suggested for high-risk patients: those with mechanical heart valves, recent stroke/TIA, or very high CHA₂DS₂-VASc scores 1

Postoperative Management

Resuming Warfarin

• Restart warfarin 12-24 hours after surgery if hemostasis is adequate and bleeding risk is acceptable 1
• Resume at the patient's usual maintenance dose 2
• Do not restart warfarin until bleeding is completely controlled and the surgical site is stable 2

Anticoagulation Duration Post-Surgery

• Continue therapeutic anticoagulation indefinitely based on her ongoing atrial fibrillation and stroke risk, irrespective of the surgical procedure 1
• The indication for anticoagulation (atrial fibrillation) persists after thyroidectomy 1

INR Monitoring

• Check INR 24-48 hours after restarting warfarin, then every 24-48 hours until therapeutic range (2.0-3.0) is re-established 1
• Once stable, resume routine monthly INR monitoring 1

Critical Pitfalls to Avoid

• Do NOT use bridging anticoagulation in this low-to-moderate risk patient—it increases major bleeding without reducing stroke 1
• Do NOT routinely administer preoperative vitamin K unless INR remains >1.5 the day before surgery, as high-dose vitamin K can cause warfarin resistance postoperatively 2
• Do NOT restart warfarin too early if there is any concern about surgical site bleeding or hemostasis 2
• Do NOT use fresh frozen plasma or prothrombin complex concentrate for routine preoperative INR reversal in elective surgery—simply stopping warfarin 5 days in advance is sufficient 2