emDOCs Podcast – Episode 96: Lower GI Bleeding

Today on the emDOCs cast we cover lower GI bleeding and what you need to know regarding diagnosis and treatment.

Episode 96: Lower GI Bleeding



  • Defined as bleeding distal to the ligament of Treitz.
  • Over 110,000 admissions and 270,000 ED visits in the U.S. annually.
  • Etiologies: anatomic (e.g., diverticular bleeding), vascular (e.g., angiodysplasia, ischemic), inflammatory (e.g., infectious, inflammatory bowel disease), and neoplastic. Diverticular bleeding is the most common etiology overall.
  • Up to 85% of cases resolve spontaneously. Rebleeding can occur in up to 38% of patients within one year, and 25% will require blood product transfusion. Mortality rates can reach 4% in admitted patients.



  • Most patients will present with hematochezia or bright red blood per rectum.
  • Up to 15% of patients with severe hematochezia will have an upper GI source, and lower GI bleed can present with melena if the source is more proximal
  • LGIB factors: history of LGIB (LR+ 6) and presence of blood clots per rectum (LR+ 20).
  • UGIB factors: history of UGIB (LR+ 6), patient reported melena (LR+ 5.1-5.9), melena on examination (LR+ 25), age < 50 years (LR+ 4), history of peptic ulcer disease or decompensated liver disease (LR+ 6), BUN:Cr > 30 (LR+ 7.l5).
  • Consider upper GI bleeding in patients who are toxic or unstable, or those who have significant amount of rectal bleeding.



  • CTA is the first line imaging modality for those with severe, active bleeding. Sensitivity and specificity over 90% if the patient is actively bleeding.
  • CTA is not necessarily in all patients with LGIB. 2023 American College of Gastroenterology and British Society of Gastroenterology guidelines recommend CTA in patients with hemodynamically significant LGIB (e.g., shock index > 1, evidence of poor systemic perfusion).
    • In other patients who are stable and the bleeding has resolved, CTA is of low yield
  • If they are critically ill and have severe bleeding, resuscitate first and consult IR, radiology, and surgery.
  • Multiphase CT imaging: noncontrast CT, venous phase, and arterial phase imaging; obtain while patient is bleeding.
    • This will increase diagnostic capability and guide further management with embolization.
    • Do not use oral contrast.
  • If CTA is negative, the likelihood of spontaneous resolution is high with a lower risk of rebleeding.


Blood Product Transfusion:

  • If the patient has significant bleeding and is unstable, transfuse blood products.
  • If the patient is stable, multiple studies and guidelines recommend transfusion thresholds of 7 g/dL for hemoglobin, including the AABB. Consider 8 g/dL in patients with myocardial ischemia or cardiac history.
    • Post-hoc analysis of patients with LGIB compared a liberal transfusion threshold of 9 g/dL (8 g/dL in those with acute coronary syndrome) with restrictive strategy and found no difference in in-hospital mortality.
  • Platelets: Guidelines recommend platelet transfusion for patients with severe LGIB and platelet count < 30 X 109/L, with a higher threshold of 50 X 109/L if endoscopy is necessary.
    • 2023 ACG guidelines recommend against transfusing platelets to reverse an antiplatelet agent.


Anticoagulation Reversal:

  • Reversal may be necessary based on patient hemodynamic status, bleeding severity, laboratory testing (e.g., PT/INR, aPTT), and timing of diagnostic and interventional procedures (i.e., colonoscopy).
    • If the patient has minor bleeding and has resolved, reversal is likely unnecessary.
    • If the bleeding is severe, reverse based on the agent.
    • Vitamin K antagonists (warfarin): vitamin K plus PCC.
    • DOACs: Patients on a DOAC who present with minor bleeding that has resolved don’t need reversal. If bleeding is more significant but the patient is otherwise stable, the medication can be withheld without reversal (medication effect dissipates within 24 hours). If severe bleeding, administer PCC. There is no clear improvement with idarizucimab or andexanet alfa on patient-oriented outcomes.
  • TXA: Several studies have found no benefit in patient-oriented outcomes with TXA in patients with significant lower GI bleeding. The ACG 2023 guidelines recommend against IV TXA for LGIB.


Colonoscopy and Bleeding Control:

  • Colonoscopy is the diagnostic and treatment modality of choice. If the patient is admitted, guidelines recommend colonoscopy during the inpatient stay, but urgent colonoscopy (< 24 hours) is not recommended in all stable patients based on current literature and 2023 ACG guidelines.
    • The 2023 ACG guidelines do state that colonoscopy may be performed within 24 hours in patients at high-risk of bleeding and a high pretest probability of finding a source of bleeding (post polypectomy bleeding).
    • The 2023 guidelines state that colonoscopy may not be needed if the bleeding has subsided and the patient has had a high-quality colonoscopy with adequate bowel preparation within 12 months showing diverticulosis and no colorectal neoplasia.
  • Severe bleeding and hemodynamically unstable patients: Not the time for colonoscopy; resuscitate and get the CTA. Colonoscopy is not recommended
    • If the CTA is negative, colonoscopy will be necessary, but an upper endoscopy should be performed first to evaluate for an upper GI bleed.
  • If CTA shows extravasation, embolization is effective in 95% of cases. Angiography and embolization performed within 90 minutes after a CTA increases the chance of controlling the bleeding by 9-fold.
  • If the embolization is unsuccessful, laparotomy may be necessary.


Risk Scores and Disposition:

  • There are multiple decision tools for lower GI bleeding: BLEED score, NOBLADs, Oakland score, SHA2PE score, and Strate score.
  • Multiple guidelines (ACG, British, European) recommend the Oakland score. This score includes age, sex, history of LGIB, digital rectal examination (DRE) findings, heart rate, systolic blood pressure, and hemoglobin.
    • An Oakland score of ≤ 8 has over a 95% probability in predicting safe discharge. One study found a score ≤ 8 points had a sensitivity of 98% for safe discharge; score ≤ 10 points had a sensitivity of 96%.
    • 2023 meta-analysis comparing scores found Oakland was the best at predicting safe discharge, major bleeding, need for blood product transfusion.
  • Do not use scores in isolation. They should only supplement your decision making. For disposition, consider other factors including rate and severity of the bleeding, if the patient has had recurrent bleeding in the ED, their social factors and other comorbidities, other symptoms like severe fatigue or dyspnea, and their ability to follow up.


Further Reading:

Lower Gastrointestinal Bleeding: Evaluation, Management, and Disposition

Guideline Update: Acute Lower GI Bleeding



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