Warfarin Management for Colonoscopy: Bridging Recommendations
Bridging with low molecular weight heparin (LMWH) during warfarin interruption for colonoscopy should be limited only to patients at high risk of thromboembolism, as bridging increases bleeding risk without reducing thrombotic events in most patients. 1
Risk Stratification for Bridging Decision
High Thrombotic Risk Patients (Require Bridging)
- Mechanical heart valves (especially mechanical mitral valve, caged ball or tilting disk valve) 2
- Mechanical heart valve with recent stroke/TIA (<3 months) 2
- Atrial fibrillation with mitral stenosis 1
- Recent venous thromboembolism (<1 month) 2
- Atrial fibrillation with very high risk factors (CHA₂DS₂-VASc score ≥7, recent stroke/TIA <3 months) 2
- Severe thrombophilia (protein C, protein S, or antithrombin deficiency, antiphospholipid syndrome) 2
Low Thrombotic Risk Patients (No Bridging Needed)
- Non-valvular atrial fibrillation (standard risk) 1
- Factor V Leiden and prothrombin mutation F2G20210A 1
- Most thrombophilia syndromes 1
- Venous thromboembolism >1 month ago 2
Evidence Supporting Limited Bridging
Multiple studies demonstrate increased bleeding risk with bridging:
- A German registry showed heparin bridging led to higher major hemorrhage rates (2.7% vs 0.5%, p=0.01) with no reduction in thromboembolism 1
- For colonoscopy specifically, several studies have demonstrated increased postpolypectomy hemorrhage with LMWH bridging without decreasing thromboembolic events 1
- The RE-LY trial showed bridging resulted in higher major hemorrhage rates (6.5% vs 1.8%, p<0.001) with no difference in thrombosis rates 1
- A Japanese study of 16,977 patients undergoing high-risk endoscopy procedures showed significant increases in both post-procedure GI bleeding and thromboembolism in patients bridged with heparin 1
Protocol for Warfarin Management
For Low Thrombotic Risk Patients:
- Stop warfarin 5 days before colonoscopy
- Check INR prior to procedure to ensure it's <1.5
- Resume warfarin on the evening of the procedure at usual dose
- No bridging with LMWH
For High Thrombotic Risk Patients:
- Stop warfarin 5 days before colonoscopy
- Start LMWH 2 days after stopping warfarin
- Administer last dose of LMWH at least 24 hours prior to procedure
- Check INR prior to procedure to ensure it's <1.5
- Resume warfarin on the evening of the procedure at usual dose
- Restart LMWH on the day after the procedure
- Continue LMWH until INR reaches therapeutic range (≥2.0) 1, 2
Important Considerations
- All patients on warfarin should be advised of an increased risk of post-procedure bleeding compared to non-anticoagulated patients, even when warfarin is temporarily discontinued 1
- For patients with recent venous thromboembolism (<3 months), consider deferring elective high-risk procedures beyond 3 months of anticoagulation if safe to do so 1
- The risk of post-colonoscopy thromboembolic events is generally low (0.32% overall) but increases with interruption of antithrombotic agents, particularly in high-risk patients 3
- A recent multicenter study found that continuing anticoagulant therapy during endoscopic mucosal resection was associated with a low major bleeding rate (4.7%) and minimal thrombotic events 4
Common Pitfalls to Avoid
- Bridging low-risk patients unnecessarily, which increases bleeding risk without benefit
- Failing to bridge truly high-risk patients, which may increase thrombotic risk
- Restarting LMWH too soon after high bleeding risk procedures
- Continuing bridging too long after warfarin becomes therapeutic (INR ≥2.0)
- Overlooking renal function when dosing LMWH
By following these evidence-based recommendations, clinicians can optimize the balance between bleeding and thrombotic risks when managing patients on warfarin undergoing colonoscopy.