What is the management approach for a patient presenting with a lower gastrointestinal (GI) bleed, potentially with underlying conditions such as diverticulosis, angiodysplasia, or inflammatory bowel disease?

Management of Lower Gastrointestinal Bleeding

Initial Assessment and Risk Stratification

All patients presenting with lower GI bleeding should be immediately stratified using shock index (heart rate divided by systolic blood pressure), with a shock index >1 defining hemodynamic instability that requires aggressive resuscitation and CT angiography as the first diagnostic step. 1

Hemodynamic Assessment

• Calculate shock index immediately upon presentation—values >1 indicate active bleeding and predict need for hospital-based intervention 1
• Check orthostatic vital signs in stable patients, as orthostatic hypotension indicates significant blood loss requiring ICU admission 2
• Perform digital rectal examination on all patients to confirm blood in stool and exclude anorectal pathology 2

Risk Stratification for Stable Patients

• Use the Oakland score for stable patients (shock index ≤1) to determine disposition 1
• Patients scoring ≤8 points can be safely discharged from the emergency department for urgent outpatient investigation 1
• Patients scoring >8 points require hospital admission 1

The Oakland score includes: age, gender, previous LGIB admission, digital rectal examination findings, heart rate, systolic blood pressure, and hemoglobin level 1

Resuscitation Protocol

Vascular Access and Fluid Management

• Establish two large-bore IV lines in the anticubital fossae immediately 3
• Begin aggressive fluid resuscitation with normal saline while assessing hemodynamic stability 3
• Infuse 1-2 liters of normal saline initially in hemodynamically compromised patients 3
• Add plasma expanders if shock persists after 2 liters, indicating ≥20% blood volume loss 3

Transfusion Strategy

• For clinically stable patients without cardiovascular disease, use restrictive transfusion thresholds: hemoglobin trigger 70 g/L, target 70-90 g/L 2
• For patients with cardiovascular disease or massive bleeding, use hemoglobin trigger 80 g/L, target 100 g/L 2, 1
• Correct coagulopathy immediately: transfuse fresh frozen plasma for INR >1.5 and platelets for platelets <50,000/µL 2

ICU Admission Criteria

• Admit to ICU if: orthostatic hypotension present, hematocrit decrease ≥6%, transfusion requirement >2 units packed red blood cells, continuous active bleeding, or persistent hemodynamic instability despite aggressive resuscitation 2

Management Algorithm Based on Hemodynamic Status

Hemodynamically Unstable Patients (Shock Index >1)

CT angiography should be performed immediately as the first diagnostic step in unstable patients, as it provides the fastest and least invasive means to localize bleeding before any therapeutic intervention. 1, 2

Diagnostic Approach

• CTA has sensitivity of 79-95% and specificity of 95-100% for detecting active bleeding 1
• CTA can identify bleeding sources in the upper GI tract, small bowel, or colon, and guide subsequent intervention 1
• Do not perform colonoscopy as the initial approach when shock index >1—colonoscopy is reserved for stable patients or after successful localization and stabilization 2

Therapeutic Intervention

• Following positive CTA, proceed to catheter angiography with embolization within 60 minutes in centers with 24/7 interventional radiology 2
• Transcatheter embolization provides time to stabilize the patient and prepare the bowel, both contributing to better surgical outcomes if surgery ultimately becomes necessary 2
• If no lower GI source is identified on CTA, perform upper endoscopy immediately, as hemodynamic instability with bright red rectal bleeding may indicate an upper GI source 1, 3

Surgical Indications

• Surgery is indicated only when: hemodynamic instability persists despite aggressive resuscitation, blood transfusion requirement exceeds 6 units, or patient fails angiographic intervention 1, 2
• Blind segmental resection and emergency subtotal colectomy are associated with rebleeding rates as high as 33% and mortality of 33-57% 2
• Even in unstable patients, attempt localization using CTA or angiography before surgery to allow targeted treatment rather than blind resection 2

Hemodynamically Stable Patients (Shock Index ≤1)

Colonoscopy Timing and Preparation

• Colonoscopy should be performed within 24 hours after adequate bowel preparation in stable patients 1, 4
• Urgent colonoscopy (within hours) shows no advantage over early elective colonoscopy (within 24 hours) for diagnostic yield, therapeutic yield, length of stay, or transfusion requirements 1
• Colonoscopy identifies the bleeding source in 61% of stable patients 1

Endoscopic Therapy

• Provide endoscopic hemostasis for high-risk stigmata: active bleeding, non-bleeding visible vessel, or adherent clot 4
• The endoscopic modality (mechanical, thermal, injection, or combination) is guided by etiology, access to bleeding site, and endoscopist experience 4
• Consider repeat colonoscopy with endoscopic hemostasis for patients with evidence of recurrent bleeding 4

Alternative Imaging if Colonoscopy Negative

• Nuclear medicine scanning offers sensitivity of 60-93% when CTA, angiography, or colonoscopy are negative, particularly for intermittent or slow bleeding 1
• There is no evidence that repeat CTA is beneficial unless bleeding becomes more brisk 1

Anticoagulation and Antiplatelet Management

Warfarin

• Interrupt warfarin immediately at presentation 2
• For unstable hemorrhage, reverse with prothrombin complex concentrate AND vitamin K 2
• Restart warfarin at 7 days after hemorrhage for patients with low thrombotic risk 2

Direct Oral Anticoagulants (DOACs)

• Interrupt DOAC therapy immediately at presentation 2
• For life-threatening hemorrhage, administer specific reversal agents: idarucizumab for dabigatran, andexanet for anti-factor Xa inhibitors 2
• Restart DOAC at maximum 7 days after hemorrhage 2

Aspirin

• Aspirin for primary prophylaxis should be permanently discontinued 2
• Aspirin for secondary prevention (established cardiovascular disease) should not be routinely stopped; if stopped, restart as soon as hemostasis is achieved 2, 4

Etiology-Specific Considerations

Common Causes by Frequency

• Diverticulosis accounts for 20-41% of acute lower GI bleeding cases and is the most frequent cause in older adults 5, 6
• Angiodysplasia represents 3-40% of cases, with higher prevalence in elderly patients 5, 7
• Ischemic colitis accounts for 12-21% of cases and should be suspected in patients with vascular comorbidities 5
• Hemorrhoids and anorectal lesions cause 5-14% of significant bleeding episodes 5
• Colorectal cancer and polyps account for 6-27% of acute lower GI bleeding 5

Inflammatory Bowel Disease

• In IBD patients with life-threatening bleeding and persistent hemodynamic instability non-responsive to medical treatment, perform immediate surgery 1
• For acute severe ulcerative colitis with refractory hemorrhage, subtotal colectomy with ileostomy is the surgical treatment of choice 1
• In Crohn's disease, bleeding often results from focal erosion into an intestinal vessel; intraoperative ileoscopy can help localize the source 1
• Evaluate hemodynamically stable IBD patients with GI bleeding first with sigmoidoscopy and esophagogastroduodenoscopy 1

Critical Pitfalls to Avoid

• Never perform endoscopy before adequate resuscitation—this is a critical error that increases mortality 3
• Failure to consider an upper GI source in patients with hemodynamic instability can lead to delayed diagnosis; up to 11% of patients presenting with presumed lower GI bleeding have an upper GI source 1, 3
• Loss of rectal sensation is an ominous sign suggesting transmural ischemia with nerve damage requiring immediate surgical consultation 5
• Right-sided abdominal pain with maroon or bright red blood is highly suggestive of non-occlusive mesenteric ischemia, which can be precipitated by vasoconstrictive medications including metoclopramide 5
• Small bowel sources account for 0.7-9.0% of severe hematochezia and are easily missed; consider capsule endoscopy if upper endoscopy and colonoscopy are negative 1, 5

Organizational Requirements

• All hospitals routinely admitting GI bleeding patients must have: a designated GI bleeding lead clinician, access to 7/7 on-site colonoscopy with endoscopic therapy capabilities, and access to 24/7 interventional radiology either on-site or via formalized referral pathway 2

Mortality Context

• Overall in-hospital mortality for lower GI bleeding is 3.4%, but rises to 18% for inpatient-onset bleeding and 20% for patients requiring ≥4 units of red cells 2
• Mortality is generally related to comorbidity rather than exsanguination 2
• The operative mortality rate for emergency surgery is 10%, with mortality for total abdominal colectomy ranging from 27-33% 2
• Elderly patients (>65 years) have significantly higher mortality rates requiring more aggressive management 3, 5
• The presence of associated comorbidities and need for urgent surgery are the only independent risk factors for morbidity and mortality 8