Can a patient with a mildly elevated International Normalized Ratio (INR) and slightly prolonged Partial Thromboplastin Time (PTT) be cleared for surgery?

Surgical Clearance Decision for Patient with INR 1.5

Yes, you can clear this patient for surgery with an INR of 1.5 and PTT of 31, as this falls within the acceptable range for most surgical procedures. 1

INR Threshold for Safe Surgery

The American College of Chest Physicians and American Heart Association establish INR <1.5 as the standard target for major surgical procedures to minimize bleeding risk while allowing safe surgery. 2, 1 Your patient's INR of 1.5 meets this threshold exactly.

• For most surgical procedures, an INR ≤1.5 is considered safe and does not significantly increase perioperative bleeding risk 1
• Recent evidence from hip fracture surgery demonstrates that INR <1.6 is safe and does not increase transfusion or mortality risk compared to normal INR 3
• The PTT of 31 seconds is within normal range (typically 25-35 seconds) and does not contraindicate surgery 2

Risk Stratification by Procedure Type

For low-risk procedures (minor dermatologic surgery, dental procedures, endoscopy with biopsy):

• Surgery can safely proceed with INR up to 2.5-3.0 without warfarin interruption 1
• Your patient's INR of 1.5 is well below this threshold 2

For high-risk procedures (major abdominal, thoracic, or neurosurgery):

• Target INR <1.5 is appropriate and has been achieved 1
• Some guidelines suggest INR <1.2 for procedures with very high bleeding risk (transseptal cardiac catheterization, LV puncture) 2

Important Caveats

If the patient is on warfarin for a mechanical heart valve:

• Verify that warfarin was appropriately stopped 48-72 hours before surgery 2
• For high-risk patients (mechanical mitral valve, any mechanical valve with atrial fibrillation, prior thromboembolism, or LV dysfunction), bridging with therapeutic heparin should have been initiated when INR fell below 2.0 2, 1
• Do not administer vitamin K to further lower the INR, as this creates difficulty achieving therapeutic anticoagulation postoperatively and may induce a hypercoagulable state 2

If the patient requires spinal or epidural anesthesia:

• The European Society of Cardiology recommends checking INR on the day of surgery for neuraxial procedures 1
• INR 1.5 is generally acceptable, though some anesthesiologists prefer <1.4 for neuraxial blocks 2

Postoperative Management

Resume warfarin 12-24 hours after surgery when adequate hemostasis is achieved, using the patient's usual maintenance dose rather than loading doses 1

• If the patient required bridging anticoagulation, restart therapeutic heparin until INR reaches therapeutic range 2, 1
• Avoid high-dose vitamin K postoperatively as this prolongs the time to achieve therapeutic anticoagulation 1