Lower GI Bleeding (LGIB): Treatment

1. Common Causes

• In patients over 65, angiodysplasia becomes a major consideration.
• In younger patients, hemorrhoids and anal fissures dominate.
• In children, consider intussusception and Meckel's diverticulum.

2. Initial Assessment & Resuscitation

1. IV access - two large-bore peripheral IVs
2. IV fluids - crystalloid resuscitation
3. Transfusion - packed RBCs; threshold typically Hb <7 g/dL (or <8 in patients with cardiovascular disease)
4. Rule out upper GI source - hematochezia with orthostasis/hemodynamic instability has an upper GI cause in ~10-15% of cases; pass an NG tube or perform upper endoscopy if UGI source suspected
5. Labs - CBC, BMP, coagulation studies, type & screen
6. Discontinue/reverse anticoagulants as clinically appropriate

• Heart rate >100 bpm
• Systolic BP <115 mmHg
• Syncope
• Non-tender abdomen
• Hematochezia within 4 hours of evaluation
• Aspirin/NSAID use
• Active comorbidities

3. Diagnostic Workup

3a. Colonoscopy - First-Line Standard

• Colonoscopy after bowel prep (PEG purge) is the standard diagnostic and potentially therapeutic approach for hemodynamically stable patients.
• Timing: Per ACG 2023 guidelines, colonoscopy within 14 days is as effective as colonoscopy within 24 hours in stable patients. Earlier colonoscopy (within 24 hours) was historically recommended but recent evidence does not show superiority.
• Diagnoses cause in ~70-95% of cases (combination of colonoscopy + push enteroscopy + anoscopy + capsule endoscopy).
• Patients with cirrhosis, prior PUD, or history of melena should undergo panendoscopy (upper + lower).

3b. CT Angiography (CTA)

• For hemodynamically significant bleeding, CTA has ~90% sensitivity for localizing the source.
• Should precede interventional angiography to guide selective catheterization.
• Detects bleeding rates as low as 0.3-0.5 mL/min.

3c. Radionuclide (Tc-99m) Scan

• Detects bleeding rates as low as 0.1 mL/min.
• Useful for localizing intermittent or slow bleeding before angiography.

3d. Mesenteric Angiography

• For ongoing active bleeding not amenable to colonoscopy or when colonoscopy is non-diagnostic.
• Active extravasation seen as localized contrast accumulation during arterial phase, persisting through venous phase.
• Use CO2 as contrast agent if standard contrast fails to locate the source.

4. Endoscopic Treatment

• About one-third of patients with true diverticular hemorrhage have SRH at urgent colonoscopy.
• Endoscopic hemostasis was required in 39% of severe hematochezia patients in large series (UCLA CURE data).
• Sleisenger & Fordtran's GI and Liver Disease notes that the specific technique depends on the nature of the target lesion.

5. Angiographic Interventions

• Vasopressin infusion (selective intra-arterial): Controls bleeding in up to 80% of patients, but rebleeding rate is high (~50%). Contraindicated in coronary artery disease (risk of MI).
• Superselective embolization: Treatment of choice via angiography. Uses a 3 Fr coaxial catheter system for superselective catheterization with minimal risk of intestinal necrosis. Effective for diverticular bleeding, angiodysplasia, and post-polypectomy hemorrhage.
• Provocative angiography: Anticoagulation + intra-arterial vasodilator (nitroglycerin, tolazoline, papaverine) + TPA to unmask occult bleeding sources.

6. Surgical Treatment

• Segmental colonic resection: For localized, confirmed bleeding source (e.g., right hemicolectomy for right-sided diverticular or angiodysplastic bleeding).
• Subtotal colectomy: When bleeding source cannot be localized preoperatively; avoids blind segmental resection with high rebleed risk.
• Surgery was required in 24% of severe hematochezia patients in historical series (UCLA CURE). Rebleeding rate after resection for diverticular hemorrhage: ~4%.
• Mortality is higher with emergency surgery; every effort should be made to localize the bleeding first.

7. Condition-Specific Considerations

8. Anticoagulation Management

• Anticoagulant reversal should be considered for life-threatening bleeding:
  • Warfarin: Vitamin K + 4-factor PCC or FFP
  • DOACs: Specific reversal agents (idarucizumab for dabigatran, andexanet alfa for Xa inhibitors)
• NSAIDs and antiplatelet agents should be held during acute episodes.
• Restart of anticoagulation/antiplatelet therapy should be individualized once bleeding is controlled (typically within days to weeks for high-thrombotic-risk patients).

9. Post-Hospitalization & Prevention

• Rebleeding from diverticulosis: ~18-38% over 4 years; documented SRH group has higher rates.
• Elective resection considered for recurrent, high-volume diverticular bleeding after two or more significant episodes.
• Aspirin/NSAID reduction: Key modifiable risk factor for all-cause LGIB recurrence.
• Surveillance colonoscopy to exclude polyps or malignancy.

• Sleisenger and Fordtran's Gastrointestinal and Liver Disease, Management of Severe Hematochezia (Chapter 20)
• Yamada's Textbook of Gastroenterology, 7e, Lower GI Bleeding (Chapter 138)
• Tintinalli's Emergency Medicine, Lower Gastrointestinal Bleeding (Chapter on Emergency GI)
• Fischer's Mastery of Surgery, 8e, Lower GI Bleeding
• ACG 2023 Updated Guidelines: Management of Acute Lower GI Bleeding (AAFP summary)
• BSG 2025 Guidelines on Acute LGIB (BSG)
• Meine GC et al. (2026). Endoscopic therapies for colonic diverticular bleeding: a systematic review and meta-analysis. Surg Endosc [PMID: 41466134]