What is the recommended evaluation and management of lower Gastrointestinal (GI) bleeding in adults?

Evaluation and Management of Lower GI Bleeding in Adults

The recommended evaluation of lower GI bleeding in adults should follow a systematic approach starting with risk stratification, followed by diagnostic colonoscopy, with consideration of radiographic studies for unstable patients or when endoscopy is not feasible. 1

Initial Assessment and Risk Stratification

• Patients presenting with lower GI bleeding should be stratified as unstable (shock index >1) or stable, with stable bleeds further categorized as major or minor using risk assessment tools like the Oakland score 1
• Initial assessment should include history of comorbidities and medications that promote bleeding, hemodynamic parameters, physical examination (including digital rectal examination), and laboratory markers 2
• The Oakland score can identify patients suitable for outpatient management (score ≤8) versus those requiring hospital admission (score >8) 1
• Patients can be categorized into four groups: minor bleeding that resolves with conservative therapy (75-90% of cases), chronic intermittent bleeding, severe life-threatening bleeding with periods of stability, or continual active bleeding 1

Resuscitation and Blood Transfusion

• Resuscitation should occur concurrently with the initial evaluation, including fluid resuscitation and blood transfusion if necessary for hemodynamic instability 1
• For hemodynamically stable patients with no history of cardiovascular disease, implement a restrictive red blood cell transfusion strategy (hemoglobin threshold ≤7 g/dL) 2
• For patients with acute or chronic cardiovascular disease, use a more liberal transfusion strategy (hemoglobin threshold ≤8 g/dL) with a post-transfusion target of ≥10 g/dL 2
• Coagulopathy (INR >1.5) or thrombocytopenia (<50,000/μL) should be corrected with fresh frozen plasma or platelets, respectively 1

Diagnostic Approach

Upper GI Endoscopy

• For patients with severe hematochezia and hypovolemia, an upper GI source should be considered, as it accounts for 10-15% of such cases 1
• Upper endoscopy should be performed early in patients with risk factors for peptic ulcer, portal hypertension, or angiodysplasia 1
• Nasogastric lavage before upper endoscopy is warranted if there is medium to low suspicion of an upper GI source 1

Colonoscopy

• Colonoscopy is the diagnostic procedure of choice for acute lower GI bleeding with a diagnostic accuracy of 72-86% 1
• Colonoscopy should be performed during the hospital stay for patients with major acute lower GI bleeding 2
• The diagnostic yield of colonoscopy is very high and should be recommended in the workup of patients presenting with bleeding per rectum 3
• Urgent colonoscopy after rapid bowel cleansing is feasible and useful in patients with severe hematochezia 1

Radiographic Studies

• For hemodynamically unstable patients with suspected ongoing bleeding, CT angiography should be performed before endoscopic or radiologic treatment to locate the bleeding site 2
• Plain abdominal radiography should be performed prior to colonoscopy if bowel perforation or obstruction is suspected 1
• Multidetector CT (MDCT) has an evolving role in localizing acute lower GI bleeding with an accuracy rate of 54-79% 1

Radionuclide Imaging

• Radionuclide imaging detects active bleeding at rates of 0.1-0.5 mL/min and is more sensitive than angiography but less specific than endoscopic or angiographic study 1
• [99Tcm] pertechnetate-labeled red blood cell scanning is preferred for evaluation of lower GI bleeding which may be episodic 1
• Early scans (<4 hours after baseline) may be helpful in localizing the bleeding site, while delayed scans are less efficient 1
• A positive red blood cell scan should be followed by urgent angiography within 1 hour 1

Management Algorithm

1. Initial Assessment and Resuscitation

   • Assess hemodynamic status and initiate resuscitation as needed 1
   • Calculate shock index and Oakland score for risk stratification 1

2. For Hemodynamically Stable Patients:

   • Perform colonoscopy as the first-line diagnostic procedure 1
   • Consider upper endoscopy if upper GI source is suspected 1

3. For Hemodynamically Unstable Patients:

   • Perform CT angiography to locate the bleeding site 2
   • Consider urgent angiography or surgery for continual active bleeding 1

4. If Bleeding Source Not Identified:

   • Consider radionuclide imaging followed by angiography 1
   • Evaluate small bowel with enteroscopy or video capsule endoscopy 1

Management of Anticoagulation and Antiplatelet Therapy

• Vitamin K antagonists should be withheld in patients with major lower GI bleeding, with coagulopathy corrected according to bleeding severity and thrombotic risk 2
• Direct oral anticoagulants should be temporarily withheld at presentation in patients with major lower GI bleeding 2
• Low-dose aspirin for secondary cardiovascular prevention should not be withheld; if stopped, it should be resumed preferably within 5 days 2
• For patients on dual antiplatelet therapy, aspirin should be continued while the P2Y12 receptor antagonist can be continued or temporarily interrupted based on bleeding severity and ischemic risk 2

Common Pitfalls and Caveats

• Failure to consider an upper GI source in patients with severe hematochezia can lead to delayed diagnosis and treatment 1
• Delayed colonoscopy may reduce diagnostic yield, particularly for identifying stigmata of recent hemorrhage 1
• Overreliance on radionuclide imaging without confirmatory tests (colonoscopy, angiography) before surgery can lead to incorrect localization 1
• Premature discontinuation of antiplatelet therapy in patients with high cardiovascular risk can increase morbidity and mortality 2