A patient on warfarin has an International Normalized Ratio of 2.0 and a prothrombin time of 20.8 seconds before surgery; how should I manage anticoagulation preoperatively?

Preoperative Management of INR 2.0 in a Patient on Warfarin

For a patient with INR 2.0 and prothrombin time 20.8 seconds before elective surgery, discontinue warfarin 5 days before the procedure to allow INR to fall to ≤1.5, and check INR the day before surgery to confirm adequate reduction. 1

Warfarin Discontinuation Strategy

• Stop warfarin 5 days (approximately 115 hours) before the scheduled procedure, as this washout period is sufficient for patients with baseline INR 2.0-3.0 to reach INR ≤1.5 preoperatively 1
• The current INR of 2.0 is at the lower end of therapeutic range, making a 5-dose washout period appropriate for most patients 1
• Check INR on the day before surgery to verify it has fallen to ≤1.5, which is the recommended target for safe surgical intervention 1

Management Based on Day-Before-Surgery INR

If INR ≤1.5 on Day Before Surgery

• Proceed with surgery as planned without additional intervention 1
• This INR level permits safe surgical hemostasis for most procedures 1

If INR Remains Elevated (≥1.8) on Day Before Surgery

• Administer low-dose oral vitamin K 1-2.5 mg to accelerate INR reduction 1
• This dose is sufficient to bring INR into acceptable range without causing prolonged warfarin resistance 1
• Recheck INR on morning of surgery to confirm INR ≤1.5 1

Bridging Anticoagulation Decision

The decision to use bridging anticoagulation with heparin depends critically on the patient's thromboembolic risk and the surgical bleeding risk. 1

Low Thromboembolic Risk (No Bridging Needed)

• Patients with atrial fibrillation without prior stroke/TIA, mechanical aortic valve without risk factors, or remote venous thromboembolism (>12 months ago) 1
• Simply discontinue warfarin 5 days before surgery and resume postoperatively 1

High Thromboembolic Risk (Bridging Recommended)

• Patients with mechanical mitral valve, any mechanical valve with prior thromboembolism, recent VTE (<3 months), or antiphospholipid syndrome with recurrent thrombosis 1
• Start therapeutic-dose LMWH 36 hours after the last warfarin dose (approximately 3 days before surgery) 1
• Give last LMWH dose 24 hours before surgery at half the normal daily dose to minimize residual anticoagulant effect 1
• Resume LMWH 24 hours postoperatively at full therapeutic dose for minor procedures 1

Special Considerations for High-Bleed-Risk Procedures

• For neurosurgical, cardiovascular, or other very high bleeding risk procedures, wait a full 48-72 hours before reinitiating postprocedural heparin bridging 1
• Consider stepwise increase from prophylactic to therapeutic LMWH dosing over first 24-48 hours postoperatively 1
• Some very high-risk procedures may warrant no postprocedural heparin bridging, using only mechanical prophylaxis instead 1

Postoperative Warfarin Resumption

• Resume warfarin at the usual maintenance dose on the evening of surgery or next morning once adequate hemostasis is achieved 1
• Continue LMWH bridging (if used) until INR returns to therapeutic range for 2 consecutive days 1
• Some clinicians give twice the maintenance dose initially, though standard maintenance dosing is also acceptable 1

Critical Pitfalls to Avoid

• Do not use high-dose vitamin K (≥10 mg) preoperatively, as this creates warfarin resistance lasting days and makes postoperative re-anticoagulation difficult 1, 2
• Do not discontinue LMWH too close to surgery time, as residual anticoagulant effect increases bleeding risk 1
• For patients with mechanical valves, avoid rapid INR reversal with high-dose vitamin K, as this may increase valve thrombosis risk 1
• Elderly patients, those with high-intensity INR ranges (3.0-4.0), or those on longer-acting coumarins may require longer washout periods than 5 days 1