What are the causes of a lower gastrointestinal (GI) bleed?

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From the Guidelines

Lower gastrointestinal (GI) bleeding is most commonly caused by diverticulosis, accounting for 30% of cases, followed by other causes such as inflammatory bowel disease, neoplasms, stress ulcers, surgical anastomoses, vascular lesions, and portal hypertension 1. The causes of lower GI bleed can be categorized into several groups, including:

  • Inflammatory conditions: inflammatory bowel disease
  • Neoplastic conditions: colorectal neoplasms
  • Vascular conditions: angiodysplasia, diverticulosis
  • Iatrogenic conditions: surgical anastomoses
  • Other conditions: stress ulcers, portal hypertension It is essential to note that approximately 75% of episodes of acute lower GI bleed due to diverticulosis stop spontaneously, especially in patients requiring transfusions of <4 units of blood over a 24-hour period 1. The management of lower GI bleed depends on the underlying cause, and treatment options may include endoscopic interventions, angiographic embolization, or surgery for uncontrolled bleeding. In terms of prevention, managing constipation with fiber supplements, adequate hydration, and treating underlying conditions can help reduce the risk of recurrent bleeding. It is crucial to discontinue anticoagulants, NSAIDs, and antiplatelet medications if possible to prevent further bleeding. Recurrent bleeding warrants close follow-up and possibly repeat colonoscopy or additional imaging studies to identify missed lesions.

From the Research

Causes of Lower Gastrointestinal (GI) Bleed

The causes of lower GI bleed can be attributed to various factors, including:

  • Diverticula 2, 3, 4
  • Angiodysplasias 2, 3, 4
  • Neoplasms 2, 3, 4
  • Colitis 2
  • Ischemia 2, 4
  • Anorectal disorders 2, 3
  • Postpolypectomy bleeding 2
  • Intestinal ischemia 2
  • Bleeding as a result of a separate process 2
  • Hemodynamic instability 2, 4
  • Advanced age 2
  • Comorbidity 2
  • Use of nonsteroidal anti-inflammatory drugs (NSAIDs) 4
  • Use of anticoagulants such as vitamin K antagonists and direct oral anticoagulants 5

Risk Factors

Certain risk factors can increase the likelihood of a lower GI bleed, including:

  • Advanced age 2
  • Comorbidity 2
  • Intestinal ischemia 2
  • Bleeding as a result of a separate process 2
  • Hemodynamic instability 2, 4
  • Use of NSAIDs 4
  • Use of anticoagulants such as vitamin K antagonists and direct oral anticoagulants 5

Diagnostic Considerations

The diagnosis of lower GI bleed often involves a combination of clinical evaluation, laboratory tests, and imaging studies, including:

  • Colonoscopy 2, 3, 4
  • Computed tomography angiography 5, 4
  • Nuclear scintigraphy 3
  • Capsule endoscopy 3
  • Angiography 2, 4

References

1
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

2
Research

Diagnosis and management of lower gastrointestinal bleeding.

Nature reviews. Gastroenterology & hepatology, 2009

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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