What are the initial steps in diagnosing and managing a patient with gastrointestinal (GI) bleeding, particularly in those with a history of GI issues, nonsteroidal anti-inflammatory drugs (NSAIDs) use, anticoagulants, or antiplatelet agents?

Initial Diagnosis and Management of Gastrointestinal Bleeding

Immediate Hemodynamic Assessment and Resuscitation

Establish two large-bore IV cannulae in anticubital fossae and infuse 1-2 liters of normal saline initially to restore blood pressure and maintain urine output >30 mL/hour in hemodynamically unstable patients. 1

• Check pulse, blood pressure, and orthostatic vital signs immediately to determine bleeding severity 2
• Calculate shock index (heart rate/systolic BP); a shock index ≥1 indicates active bleeding requiring urgent intervention 1
• Obtain complete blood count, coagulation studies (PT/INR), and serum creatinine 2
• Transfuse packed red blood cells when hemoglobin <100 g/L or with active hematemesis and shock 2
• Correct coagulopathy with fresh frozen plasma if INR >1.5 2

Localizing the Bleeding Source

Upper vs. Lower GI Bleeding Differentiation

Bright or dark red blood per rectum with hemodynamic instability may indicate upper GI bleeding; perform upper endoscopy first if clinical suspicion is high, particularly in patients with peptic ulcer disease history, portal hypertension, elevated BUN/creatinine ratio, or antiplatelet drug use. 1

• Risk factors suggesting upper GI source include: brisk rectal bleeding with shock, history of peptic ulcer disease, portal hypertension, and antiplatelet/anticoagulant use 1
• Do NOT routinely place a nasogastric tube in suspected upper GI bleeding—it does not reliably aid diagnosis, does not affect outcomes, and causes complications in one-third of patients 1
• Perform digital rectal examination to confirm stool appearance, exclude anorectal pathology, and detect palpable rectal masses (40% of rectal cancers are palpable) 2

Diagnostic Algorithm for Unstable Patients

For hemodynamically unstable lower GI bleeding (shock index ≥1), perform CT angiography (CTA) as the first investigation rather than colonoscopy, as CTA can localize bleeding in the upper GI tract or small bowel, requires no bowel preparation, and is rapidly accessible. 1

• CTA should be performed in the arterial phase, not just portal-venous phase, for optimal detection of active bleeding 1
• If CTA shows no source and patient remains unstable with suspected upper GI bleeding, proceed immediately to upper endoscopy 1
• Bright red rectal bleeding may indicate anorectal source; perform direct anorectal inspection first 1
• If anoscopy and CTA are negative, proceed to full colonoscopy 1

Diagnostic Algorithm for Stable Patients

For hemodynamically stable patients, colonoscopy is the preferred diagnostic modality and should be performed within 24 hours after adequate bowel preparation, with a diagnostic yield of 42-90% and allowing therapeutic intervention. 2, 3

• In stable patients with high suspicion of upper GI bleeding, perform gastroscopy after adequate resuscitation 1
• For patients over 50 years old with rectal bleeding, perform full colonoscopy as colorectal cancer risk ranges from 2.4-11% 2
• Consider diverticulosis and angiodysplasia as common causes in patients ≥70 years old 2

Management of Anticoagulants and Antiplatelets

Anticoagulant Management

Immediately discontinue warfarin at presentation; for severe hemorrhage with hemodynamic instability, reverse with prothrombin complex concentrate and vitamin K. 1

• Warfarin has a long half-life (3-5 days); simple discontinuation suffices for low-risk hemorrhage 1
• For direct oral anticoagulants (DOACs), withhold medication; most do not require specific reversal agents 1

Antiplatelet Management

For patients on aspirin for secondary prevention (prior MI, stroke, or established cardiovascular disease), do NOT routinely discontinue aspirin—if stopped, resume immediately after hemostasis is achieved, as mortality is 10 times lower in patients who continue aspirin (1.3% vs 12.9%) despite slightly higher rebleeding risk. 4

• Patients who stop aspirin have nearly 7-fold increased risk of death or acute cardiovascular events (HR 6.9; 95% CI 1.4-34.8) 4
• For P2Y12 inhibitors (clopidogrel, ticagrelor, prasugrel), resume within maximum 5 days after hemostasis due to high thrombosis risk, especially with coronary stents 4
• For dual antiplatelet therapy (DAPT), never stop both agents simultaneously—continue aspirin and temporarily hold P2Y12 inhibitor, as stopping both causes median stent thrombosis at 7 days versus 122 days if only clopidogrel stopped 4
• For aspirin used for primary prevention only, discontinue permanently after GI bleeding as risks exceed benefits 4
• Do NOT transfuse platelets routinely in patients on antiplatelet agents with GI bleeding—this does not reduce rebleeding but is associated with higher mortality 4

Timing of Anticoagulation Resumption

For high thrombotic risk patients (prosthetic metal mitral valve, atrial fibrillation with prosthetic valve or mitral stenosis, <3 months after venous thromboembolism), resume low molecular weight heparin at 48 hours after hemostasis. 1, 5

For low thrombotic risk patients (standard atrial fibrillation without high-risk features), resume anticoagulation at 7 days after hemorrhage stops, as starting before 7 days results in twofold increase in rebleeding without significant reduction in thromboembolism. 1, 5

• Starting anticoagulation between 7-15 days reduces thromboembolic events and mortality with no increase in rebleeding 1, 5

When Initial Investigations Are Negative

If CTA, upper endoscopy, and colonoscopy are all negative, consider video capsule endoscopy (VCE) for overt-obscure GI bleeding, which has diagnostic yield of 50-72% and should be performed as close as possible to the bleeding episode. 1

• VCE permits examination of entire small bowel in 79-90% of patients 1
• Three RCTs show VCE has higher diagnostic yield than small bowel radiography, catheter angiography, and push enteroscopy for obscure bleeding 1
• Nuclear medicine (red cell scintigraphy) offers 60-93% sensitivity for intermittent or slow bleeds when other investigations are negative 1
• Do NOT repeat CTA unless bleeding becomes more brisk—no benefit shown for repeat CTA within 24 hours 1
• Mesenteric angiography is unlikely beneficial in hemodynamically stable patients within 24 hours of negative CTA 1

Special Considerations During COVID-19 or High-Risk Situations

In critically ill or high-risk patients with indeterminate upper GI bleeding, pursue alternative diagnostic modalities such as CT angiography and bedside real-time viewer capsule endoscopy before endoscopy to minimize exposure and focus only on therapeutic procedures. 1

• Consider proton pump inhibitor infusions over intermittent IV administration 1
• Liberalize octreotide infusions for patients with suspected or known liver disease 1
• Use scheduled antiemetics, platelets, and/or clotting factors to correct coagulopathies 1
• Photographic documentation of bleeding (emesis basin, bedsheets, toilet bowls) helps confirm symptoms and guide remote decisions 1
• Defer endoscopic evaluation for anemia without overt bleeding, small-volume bleeding, or self-limited bleeding until resources permit 1

Common Pitfalls to Avoid

• Never proceed to emergency laparotomy without localizing bleeding by radiological and/or endoscopic modalities except under exceptional circumstances (e.g., aortoenteric fistula) 1
• Do not use nasogastric tube lavage in unsedated patients due to risk of gagging, vomiting, and aerosolization 1
• Do not transfuse red blood cells liberally—use restrictive thresholds (Hb trigger 70 g/L, target 70-90 g/L) unless cardiovascular disease present (trigger 80 g/L, target 100 g/L) 1
• Discuss with cardiology before stopping antiplatelet therapy, especially in patients with acute coronary syndrome within 6 months 4