What are the guidelines for spinal anaesthesia in a patient with elevated International Normalized Ratio (INR) due to anticoagulation therapy with warfarin or novel oral anticoagulants (NOACs) such as apixaban (eliquis) or rivaroxaban (xarelto)?

Spinal Anaesthesia and INR Management

For spinal anaesthesia, the INR must be ≤1.4 before proceeding with neuraxial blockade to minimize the risk of catastrophic spinal hematoma. 1

INR Thresholds for Safe Neuraxial Procedures

The evidence establishes clear cutoffs based on bleeding risk stratification:

• INR ≤1.4: Normal risk for spinal hematoma, safe to proceed with neuraxial blockade 1
• INR 1.5-1.8: Increased risk; consider low-dose oral vitamin K (1-2.5 mg) for reversal and recheck INR before proceeding 1
• INR 1.7-2.0: High risk; neuraxial procedures should be deferred 1
• INR >2.0: Very high risk and absolute contraindication to neuraxial procedures 1

The Association of Anaesthetists of Great Britain & Ireland specifically recommends INR ≤1.4, which is more conservative than the American College of Chest Physicians threshold of ≤1.5. 1 Given the catastrophic consequences of spinal hematoma, the more conservative threshold of ≤1.4 should be followed. 1

Warfarin Management Protocol

For patients on chronic warfarin therapy requiring spinal procedures:

• Discontinue warfarin 5 days preoperatively to allow INR to decrease naturally to ≤1.5 2, 1
• Check INR the day before surgery to confirm adequate reduction 1
• If INR remains 1.5-1.8 on day-before-surgery check, administer oral vitamin K 1-2.5 mg and recheck INR on day of procedure 1
• Verify INR on day of procedure before proceeding, particularly for high-risk procedures like spinal laminectomy 2

The INR naturally decreases to ≤1.5 within approximately 115 hours (4.8 days) after withholding warfarin in most patients. 2

Novel Oral Anticoagulants (NOACs) Management

Critical pitfall: INR is not valid for monitoring NOACs and should never be used to guide neuraxial anesthesia timing in patients on apixaban, rivaroxaban, or dabigatran. 1 Time-based protocols are mandatory:

Apixaban and Rivaroxaban (Factor Xa Inhibitors)

• Discontinue 3 days (72 hours) before neuraxial procedures in patients with normal renal function 1
• Longer discontinuation periods required with renal impairment 1

Dabigatran (Direct Thrombin Inhibitor)

• Discontinue 5 days before neuraxial blockade in patients with normal renal function 1
• Significantly longer discontinuation required with renal impairment 1

Epidural Catheter Removal Considerations

Catheter removal carries the same bleeding risk as insertion and must follow identical INR criteria (≤1.4). 1 Common pitfalls include:

• Do not restart warfarin until after catheter removal 1
• If warfarin must be restarted while catheter remains in situ, ensure INR remains ≤1.4 1
• Delay catheter removal if INR exceeds 1.4 1

Emergency Surgery with Elevated INR

For urgent/emergency spinal procedures in patients with elevated INR:

• Administer 4-factor prothrombin complex concentrate (PCC) 50 IU/kg IV for rapid reversal 1
• Add intravenous vitamin K 10 mg by slow infusion over 30 minutes 1
• PCC achieves INR correction within 5-15 minutes versus hours with fresh frozen plasma 1
• Target INR <1.5 before proceeding 2

Important caveat: High-dose vitamin K (10 mg) may preclude re-warfarinization for several days, complicating postoperative anticoagulation management. 1 For patients requiring rapid return to therapeutic anticoagulation, consider lower vitamin K doses (1-2 mg) if bleeding risk permits. 1

Postprocedural Anticoagulation Resumption

Timing of anticoagulation resumption depends on bleeding risk:

Standard Spinal Procedures

• Resume warfarin at usual maintenance dose the evening of or morning after procedure once adequate hemostasis achieved 2

High Bleeding-Risk Spinal Procedures (e.g., laminectomy, neurosurgical procedures)

• Delay anticoagulation resumption 48-72 hours after procedure, even in patients at high thrombotic risk 2
• Consider stepwise low molecular weight heparin dosing: prophylactic dose for first 24-48 hours, then intermediate/treatment dose 2
• Avoid treatment-dose LMWH bridging immediately postoperatively in major neurosurgical cases due to high major bleeding rates 2

Risk Factors Requiring Extra Caution

The following factors amplify bleeding risk and warrant more conservative management: 3

• Advanced age (>65 years) 3
• Multiple attempts at neuraxial access 4
• Cervical spine procedures (higher risk than lumbar) 4
• Anatomic abnormalities: spondylosis, ankylosing spondylitis, spinal stenosis 4
• Large bore needles 4

Antithrombotic prophylaxis or therapy must be used with extreme caution in all patients undergoing spinal puncture for diagnosis, therapy, or regional anesthesia. 3