Is spinal anaesthesia safe in an adult with an INR of 1.4, a normal platelet count, and no recent anticoagulant use?

Spinal Anaesthesia with INR 1.4: Safety Assessment

Yes, spinal anaesthesia can be safely administered with an INR of 1.4, as this falls within the "normal risk" category according to established guidelines. 1

Guideline-Based Risk Stratification

The Association of Anaesthetists of Great Britain & Ireland explicitly categorizes neuraxial procedures by INR level 1:

• INR ≤ 1.4: Normal risk – proceed with spinal anaesthesia
• INR 1.4–1.7: Increased risk – requires careful consideration
• INR 1.7–2.0: High risk – generally avoid
• INR > 2.0: Very high risk – contraindicated

Your patient with INR 1.4 sits at the upper boundary of the normal risk category, making spinal anaesthesia acceptable. 1

Critical Pre-Procedure Verification

Before proceeding, confirm the following to ensure the INR 1.4 represents true normal coagulation 1:

• No recent warfarin or anticoagulant use – the question states this is confirmed
• Normal platelet count – the question states this is confirmed (should be ≥70 × 10⁹/L per current consensus) 2
• No concurrent antiplatelet agents (clopidogrel, prasugrel, ticagrelor within 7 days) 2
• No clinical signs of coagulopathy (bleeding, bruising, petechiae)
• INR measured within 24 hours of the planned procedure 1

Supporting Evidence for Safety

A large observational study of 4,365 patients demonstrated zero spinal hematomas (0% incidence, 95% CI 0–0.069%) when epidural catheters were removed at INRs ranging from 1.5 to 7.1 during warfarin initiation, though this was specifically during the early phase when vitamin K-dependent factors remain adequate. 3 While this study examined catheter removal rather than insertion, it provides reassurance that INR 1.4 carries minimal bleeding risk in the context of recent warfarin initiation or no anticoagulation.

The International Society on Thrombosis and Haemostasis 2025 consensus requires INR ≤1.4 before neuraxial procedures in patients on warfarin. 2 This threshold is based on moderate-level guideline evidence and represents the standard of care.

Risk-Benefit Consideration

The primary risk of neuraxial anaesthesia with mildly elevated INR is vertebral canal haematoma with cord compression, which can cause permanent neurological damage if not evacuated within 8–12 hours. 1 However, at INR 1.4 without other risk factors, this risk remains extremely low.

The alternative—general anaesthesia—carries its own significant risks, particularly in obstetric patients or those with full stomachs, including difficult airway management, aspiration, and thromboembolic complications. 1 This risk-benefit comparison often favors neuraxial techniques even at the upper limit of normal INR.

Common Pitfalls to Avoid

• Do not proceed if INR is trending upward or if the patient has received warfarin doses that have not yet reached steady-state effect 1
• Do not assume normal coagulation based on INR alone – verify platelet count and clinical assessment for bleeding 1
• Do not proceed if the patient has received LMWH within 12 hours (prophylactic dose) or 24 hours (therapeutic dose) 1
• Do not proceed if concurrent coagulation abnormalities exist (prolonged aPTT, low fibrinogen <200 mg/dL) 2

Post-Procedure Monitoring

After spinal anaesthesia, implement mandatory safety monitoring 2, 4:

• Test straight leg raise at 4 hours after the last dose of local anaesthetic
• Document motor block resolution using the Bromage scale
• Immediate assessment required if unable to perform straight leg raise at 4 hours
• Urgent neuroimaging for any progressive neurological deficits, as epidural hematoma causes irreversible damage if not evacuated within 8–12 hours 2, 4

Final Recommendation Algorithm

Proceed with spinal anaesthesia if:

1. INR ≤1.4 (confirmed within 24 hours) 1, 2
2. Platelet count ≥70 × 10⁹/L 2
3. No anticoagulants or antiplatelet agents (except aspirin/NSAIDs) 1, 2
4. No clinical signs of bleeding or coagulopathy 1
5. INR is stable or decreasing, not rising 1

Delay or avoid if:

• INR >1.4 or trending upward 1
• Recent anticoagulant use within specified timeframes 1, 2
• Concurrent coagulation abnormalities 2
• Rapidly falling platelet count even if absolute value adequate 2