When should warfarin (anticoagulant) be stopped before a colonoscopy?

Warfarin Management Before Colonoscopy

For colonoscopy with anticipated polypectomy or high-risk interventions, warfarin should be discontinued 5 days before the procedure and INR checked prior to ensure it is <1.5. 1, 2

Risk Stratification

Procedure Risk

• Low-risk procedures:

  • Diagnostic colonoscopy with or without biopsies
  • No interruption of warfarin needed 2, 1
  • Ensure INR is within therapeutic range in the week prior to procedure

• High-risk procedures:

  • Colonoscopy with anticipated polypectomy
  • Endoscopic mucosal resection (EMR)
  • Endoscopic submucosal dissection (ESD)
  • Requires warfarin discontinuation 2, 1

Thrombotic Risk

• Low thrombotic risk:

  • Non-valvular atrial fibrillation with CHADS₂ score ≤4
  • Bileaflet aortic valve without risk factors

  • 3 months after venous thromboembolism

  • Stop warfarin without bridging therapy 1

• High thrombotic risk:

  • Mechanical mitral valve
  • Prosthetic valve with prior thromboembolism
  • Recent (<3 months) venous thromboembolism
  • Atrial fibrillation with prior stroke or multiple risk factors
  • Requires bridging therapy with LMWH 2, 1

Management Algorithm

For Low-Risk Procedures (Diagnostic Colonoscopy ± Biopsies):

1. Continue warfarin therapy 2, 1
2. Check INR during the week before the procedure
3. Ensure INR does not exceed therapeutic range
4. If INR is above therapeutic range but <5, reduce daily warfarin dose until INR normalizes 1
5. Defer the procedure if INR exceeds 3.5 2

For High-Risk Procedures (Colonoscopy with Anticipated Polypectomy):

1. Stop warfarin 5 days before the procedure 2, 1

2. Check INR prior to procedure to ensure it is <1.5 2, 1

3. For patients with low thrombotic risk:

   • No bridging therapy required 2, 1
   • Resume warfarin the evening of the procedure with usual daily dose 1

4. For patients with high thrombotic risk:

   • Start LMWH 2 days after stopping warfarin 2, 1
   • Administer last dose of LMWH at least 24 hours before the procedure 1
   • Resume warfarin the evening of the procedure with usual daily dose 1
   • Restart LMWH the day after the procedure 2, 1
   • Continue LMWH until INR returns to therapeutic range 2, 1
   • Check INR one week after procedure to ensure adequate anticoagulation 1

Important Considerations

• The risk of post-polypectomy bleeding is significantly higher in anticoagulated patients (0.8-23%) compared to non-anticoagulated patients (0.07-1.7%) 1, 3

• Since polyps are found in 22.5-42% of colonoscopies, it is prudent to plan for possible polypectomy in most cases 1

• Even with proper warfarin interruption, patients still have an increased risk of post-polypectomy bleeding compared to those not on anticoagulation 3

• The decision to interrupt or continue anticoagulants involves considerable clinical judgment, weighing the risk of thromboembolism against the risk of bleeding 3

• Poor adherence to guidelines has been documented, particularly with warfarin management, with unwarranted drug withholding being more frequent before colonoscopy than upper endoscopy 4

• For patients on warfarin, the INR should be properly checked before the procedure, which occurs in only about 47.7% of cases according to one study 4