What is the risk of bleeding during colonoscopy in adults with varying health statuses and medical histories, including those with bleeding disorders or on anticoagulant medications such as warfarin (anticoagulant), aspirin (nonsteroidal anti-inflammatory drug), or novel oral anticoagulants (NOACs) like apixaban (Factor Xa inhibitor) or rivaroxaban (Factor Xa inhibitor)?

Risk of Bleeding During Colonoscopy

The baseline risk of clinically significant bleeding during diagnostic colonoscopy with biopsy is minimal (essentially 0%), while colonoscopy with polypectomy carries a post-polypectomy bleeding risk of 0.6-2.2%, with severe bleeding requiring transfusion occurring in approximately 0.08% of cases. 1

Baseline Bleeding Risk by Procedure Type

Diagnostic Colonoscopy with Biopsy

• No severe hemorrhage has been reported in studies involving thousands of patients undergoing diagnostic endoscopy with mucosal biopsy 1
• Diagnostic procedures with or without biopsy are classified as low-risk for hemorrhage 1
• For DOACs specifically, omit the morning dose on the day of procedure to allow an adequate safety margin, even for diagnostic procedures 1

Colonoscopy with Polypectomy

• Overall post-polypectomy bleeding (PPB) rate: 1.14% in large screening programs 1
• Severe bleeding requiring transfusion: 0.08% 1
• Delayed PPB (most clinically significant): 0.6-2.2% in large series 1
• Mean time to delayed bleeding: 4.0 ± 2.9 days 1
• Polypectomy increases bleeding risk by a factor of 11.14 compared to no polypectomy 1

Risk Stratification by Polyp Characteristics

Polyp Size (Critical Factor)

• Every 1-mm increase in polyp diameter increases PPB risk by 9% 1
• Large polyps (≥20 mm): significantly elevated risk 1
• Small polyps (<10 mm): PPB rates similar to conventional polypectomy 1

Polyp Location

• Left-sided polyps: OR 1.95 (95% CI 1-3.8) for active bleeding 2
• Proximal colon location increases bleeding risk 3

Polyp Morphology

• Pedunculated polyps: OR 1.8 (95% CI 1-3.2) for active bleeding 2

Technique-Related Factors

• Pure cutting current: OR 6.95 (95% CI 4.42-10.94) for immediate PPB compared to blended/coagulation current 1
• Cold snare polypectomy (4-9 mm polyps): no significant hemorrhage in RCT 1

Bleeding Risk on Anticoagulants and Antiplatelets

Aspirin Monotherapy

• Aspirin monotherapy has been found to be safe in colonoscopic polypectomy with no significant increase in PPB 1
• Should not be routinely stopped for secondary prevention 1

Clopidogrel (P2Y12 Inhibitors)

• Continued clopidogrel: approximately 2.4% risk of delayed PPB 4
• RCT showed no significant difference in immediate or delayed PPB when continuing clopidogrel for polyps <1 cm 1
• However, this study had high proportion on DAPT, limiting conclusions 1

Warfarin

• Even when interrupted, warfarin increases PPB risk 4
• Continued warfarin with polypectomy <1 cm: 0.8% rate of hemorrhage requiring transfusion (with routine prophylactic clipping) 1
• Hot snare vs cold snare on warfarin: immediate hemorrhage 23.0% vs 5.7%; delayed hemorrhage requiring intervention 14% vs 0% 1
• Cold polypectomy strongly preferred for patients on warfarin 1

Direct Oral Anticoagulants (DOACs: Apixaban, Rivaroxaban, Dabigatran)

• Bridging with UFH showed 12.0% major bleeding vs 4.7% on continued DOAC for cold polypectomy <1 cm 1
• Bridging is NOT recommended—British Society of Haematology guidelines should be followed 1
• For high-risk procedures, restart DOAC 24-48 hours post-procedure; immediate restart nearly doubles delayed bleeding risk 1
• Apixaban associated with lowest major bleeding risk among NOACs 5

Dual Antiplatelet Therapy (DAPT)

• Continue DAPT if possible in patients with coronary stents; manage in liaison with interventional cardiologist 1
• If major hemorrhage occurs, continue aspirin if P2Y12 inhibitor must be interrupted 1
• Reinstate P2Y12 inhibitor within 5 days if still indicated 1

Population-Specific Risk Factors

Patient Demographics

• Older age: independent risk factor for PPB 6, 3, 7
• Male sex: increased odds of bleeding 6, 7

Comorbidities

• Hypertension, diabetes, coronary artery disease, chronic obstructive pulmonary disease all increase bleeding risk 6, 3
• Decompensated cirrhosis: independent risk factor regardless of platelet count 3

Bleeding Disorders

• Type 1 von Willebrand disease: requires prophylactic VWF concentrate to achieve VWF activity ≥50 IU/dL before procedure 3
• Thrombocytopenia: platelet count >50,000/μL generally safe for colonoscopy with biopsies 3
• Platelet count 20,000-50,000/μL: diagnostic colonoscopy without biopsies potentially safe; therapeutic interventions require >50,000/μL 3

Endoscopist Experience

• Low-volume endoscopist: associated with increased odds of bleeding 7

FIT-Positive Screening Population

FIT-positive colonoscopy carries significantly higher bleeding risk than ordinary colonoscopy: 8

• Significant bleeding: 6.7 per 1000 FIT-colonoscopies 8
• Perforation: 0.9 per 1000 FIT-colonoscopies 8
• Polypectomy in FIT-positive patients: aOR 4.41 (95% CI 4.05-4.81) for complications 8
• FIT-colonoscopy vs ordinary colonoscopy: aOR 3.10 (95% CI 2.90-3.32) for significant bleeding 8
• This elevated risk reflects higher likelihood of advanced neoplasms requiring polypectomy 8

Mortality Risk

Death rate following outpatient colonoscopy: 0.074 per 1000 procedures (approximately 1 in 14,000) 7

Key Clinical Pitfalls to Avoid

• Do NOT bridge DOACs with heparin for colonoscopy—this increases bleeding risk 2.5-fold 1
• Do NOT use hot snare for small polyps in anticoagulated patients—use cold snare exclusively 1
• Do NOT assume diagnostic colonoscopy will remain diagnostic—22.5-34.2% of patients have polyps requiring polypectomy; consider managing as high-risk procedure for anticoagulation decisions 1
• Do NOT use pure cutting current—blended or coagulation current reduces immediate bleeding by 85% 1