Do I need to stop taking blood thinners, such as warfarin (anticoagulant), aspirin (acetylsalicylic acid), and nonsteroidal anti-inflammatory drugs (NSAIDs), before a colonoscopy?

Management of Blood Thinners Before Colonoscopy

Whether you need to stop blood thinners before colonoscopy depends critically on two factors: the type of procedure (diagnostic vs. therapeutic) and your thrombotic risk—for simple diagnostic colonoscopy with biopsies, continue aspirin and NSAIDs; for polypectomy or other interventions, stop warfarin 5 days before and P2Y12 inhibitors (clopidogrel) 5 days before, while aspirin can generally continue. 1

Risk Stratification of Colonoscopy Procedures

Low-Risk Procedures

• Diagnostic colonoscopy with biopsy sampling is classified as low-risk for bleeding 1
• These procedures carry minimal bleeding risk and do not require anticoagulant interruption 1

High-Risk Procedures

• Colonoscopic polypectomy is classified as high-risk for bleeding 1
• Other high-risk interventions include endoscopic mucosal resection (EMR), endoscopic submucosal dissection (ESD), and stricture dilation 1

Management by Medication Type

Aspirin and NSAIDs

Continue aspirin and NSAIDs for both diagnostic and therapeutic colonoscopy procedures. 1

• Multiple studies demonstrate that aspirin/NSAID continuation does not significantly increase postpolypectomy bleeding risk compared to patients not taking these medications 2, 3
• The postpolypectomy bleeding rate in aspirin/NSAID users is approximately 3.2% versus 3.0% in non-users—not statistically significant 3
• Do not discontinue aspirin or NSAIDs before colonoscopy, even for polypectomy 1

P2Y12 Receptor Antagonists (Clopidogrel, Prasugrel, Ticagrelor)

For Diagnostic Colonoscopy (Low-Risk)

• Continue P2Y12 inhibitors without interruption 1
• This applies to both single antiplatelet therapy and dual antiplatelet therapy (DAPT) 1

For Colonoscopy with Polypectomy (High-Risk)

Low Thrombotic Risk Patients:

• Stop clopidogrel/prasugrel/ticagrelor 5 days before the procedure 1
• If on dual antiplatelet therapy, continue aspirin while stopping the P2Y12 inhibitor 1
• Resume P2Y12 inhibitors 2-3 days after the procedure depending on hemostatic adequacy 1

High Thrombotic Risk Patients (recent coronary stents):

• Drug-eluting stents <12 months or bare metal stents <1 month: defer the procedure if possible 1
• If procedure cannot be deferred and stent placement was 6 weeks to 6 months ago: continue aspirin, stop P2Y12 inhibitor 5 days before, and coordinate with interventional cardiology 1
• Continue aspirin at minimum in all patients with coronary stents 1

Warfarin

For Diagnostic Colonoscopy (Low-Risk)

• Continue warfarin without interruption 1
• Check INR during the week before colonoscopy to ensure it remains within therapeutic range 1
• If INR is within therapeutic range, continue usual daily dose 1
• If INR is above therapeutic range but <5, reduce daily dose until INR returns to therapeutic range 1
• If INR >5, defer the procedure and contact anticoagulation clinic 1

For Colonoscopy with Polypectomy (High-Risk)

Low Thrombotic Risk Patients:

• Stop warfarin 5 days before the procedure 1
• Check INR prior to procedure to ensure <1.5 1
• Restart warfarin the evening of the procedure with usual daily dose 1
• Check INR one week later to ensure adequate anticoagulation 1
• No heparin bridging is needed for low thrombotic risk patients 1

High Thrombotic Risk Patients (mechanical heart valves, AF with high CHADS-VASc score, recent VTE):

• Stop warfarin 5 days before the procedure 1
• Start therapeutic-dose low molecular weight heparin (LMWH) 2 days after stopping warfarin 1
• Give last dose of LMWH at least 24 hours before the procedure 1
• Check INR prior to procedure to ensure <1.5 1
• Restart warfarin evening of procedure with usual dose 1
• Resume therapeutic-dose LMWH the day after procedure and continue until INR is therapeutic 1

Direct Oral Anticoagulants (DOACs)

For Diagnostic Colonoscopy (Low-Risk)

• Omit only the morning dose on the day of the procedure 1
• No other interruption is necessary 1

For Colonoscopy with Polypectomy (High-Risk)

All Patients:

• Take the last dose of DOAC at least 48 hours before the procedure 1
• For dabigatran in patients with CrCl 30-50 mL/min, take last dose 72 hours before the procedure 1
• Consult hematology for patients with rapidly deteriorating renal function 1
• Resume DOACs 2-3 days after the procedure depending on hemostatic adequacy 1
• No heparin bridging is required for DOACs 1

Critical Thrombotic Risk Definitions

High Thrombotic Risk 1

• Prosthetic mechanical heart valve (especially mitral position)
• Atrial fibrillation with previous stroke/TIA
• Atrial fibrillation with mitral stenosis
• Recent VTE (within 3 months)
• CHADS-VASc score ≥5

Low Thrombotic Risk 1

• Atrial fibrillation without high-risk factors
• Xenograft heart valve with CHADS-VASc <4
• Ischemic heart disease without recent stents
• Cerebrovascular or peripheral vascular disease

Important Caveats and Pitfalls

Common Pitfall #1: Unnecessarily stopping aspirin before colonoscopy

• Despite evidence supporting continuation, 32.5% of U.S. endoscopy units still recommend stopping aspirin 4
• This practice increases thrombotic risk without meaningful bleeding risk reduction 4

Common Pitfall #2: Failing to check INR before high-risk procedures in warfarin users

• Even when warfarin is stopped, you must verify INR <1.5 before proceeding 1
• Residual anticoagulation significantly increases bleeding risk 1

Common Pitfall #3: Inappropriate bridging with heparin

• Bridging is only indicated for high thrombotic risk patients on warfarin 1
• DOACs do not require bridging due to rapid offset 1
• Unnecessary bridging increases bleeding risk 1

Patient Counseling: All patients on anticoagulants or antiplatelets should be advised of increased post-procedure bleeding risk compared to non-anticoagulated patients, even when medications are appropriately managed 1

Special Consideration for Small Polyps: For polyps <1 cm, consider cold snare resection technique on continued clopidogrel monotherapy, as this reduces bleeding risk compared to hot snare techniques 1