What is the cause of a single episode of hematochezia (passage of blood in stool)?

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Last updated: April 6, 2025View editorial policy

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From the Guidelines

A single episode of blood in stool should prompt medical attention, especially if it's bright red blood, maroon-colored, or black, tarry stool, and the patient should contact their healthcare provider within 24-48 hours, or seek immediate emergency care if accompanied by severe symptoms 1. The presence of blood in stool can indicate various conditions, ranging from benign hemorrhoids or anal fissures to more serious issues like inflammatory bowel disease, diverticular bleeding, or colorectal cancer.

Key Considerations

  • The location of bleeding often determines the color, with bright red blood typically suggesting lower gastrointestinal tract bleeding, while darker or black stool (melena) suggests upper GI bleeding where blood has been partially digested 1.
  • The patient should document the color and amount of blood, associated symptoms, and recent medication use, particularly NSAIDs like ibuprofen or blood thinners like warfarin, and avoid self-medicating with these substances as they can worsen bleeding.
  • A physical examination and diagnostic tests such as colonoscopy, endoscopy, or imaging studies may be recommended to determine the cause and appropriate treatment.

Diagnostic Approach

  • For patients with suspected bleeding anorectal varices, ano-proctoscopy or flexible sigmoidoscopy is suggested as the first-line diagnostic tool, with urgent colonoscopy (plus upper endoscopy) within 24 hours of presentation for those with high-risk features or evidence of ongoing bleeding 1.
  • A full colonoscopy may be necessary to identify a source of bleeding, especially in patients with risk factors for colorectal cancer or suspicion of a concomitant more proximal source of bleeding 1.

Management

  • Local procedures, such as endoscopic variceal ligation, endoscopic band ligation, sclerotherapy, or EUS-guided glue injection, may be used to arrest bleeding in patients with bleeding anorectal varices, where feasible 1.
  • The patient's healthcare provider will determine the best course of management based on the underlying cause of the bleeding and the patient's individual needs.

From the Research

Causes of Blood in Stool

  • A single episode of blood in stool can be caused by various factors, including inflammatory bowel diseases (IBD) such as ulcerative colitis and Crohn's disease 2, 3, 4, 5
  • Overt gastrointestinal bleeding, which can manifest as blood in stool, is a frequently observed condition in routine gastroenterological practice 6

Risk Factors

  • Patients with IBD are at a higher risk of developing colorectal cancer (CRC) and may experience bleeding as a symptom 2, 3, 4, 5
  • The chronic inflammatory state inherent in IBD increases the risk for high-grade dysplasia and CRC, with additional input from genetic and environmental risk factors and the microbiome 3

Diagnosis and Management

  • Endoscopic imaging techniques and integrated surveillance programs are used to diagnose and manage CRC in patients with IBD 2, 4
  • Recognizing risk factors, implementing appropriate surveillance, and identifying high-risk patients are key to managing the CRC risk in IBD patients 3
  • Chemoprevention strategies exist, and studies evaluating their efficacy are underway 3

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Cancer in Inflammatory Bowel Disease.

Gastroenterology clinics of North America, 2022

Research

Acute gastrointestinal bleeding - a new approach to clinical and endoscopic management.

European journal of gastroenterology & hepatology, 2015

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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