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Bleeding from lower GI tract

Medicine > Gastrointestinal

Differential Diagnosis Schema 🧠

Anorectal Causes

  • Hemorrhoids: Painless rectal bleeding, often bright red and on the toilet paper or surface of stool.
  • Anal fissures: Sharp, painful bleeding, often with a tearing sensation during defecation.
  • Rectal varices: Associated with portal hypertension, presents with more significant bleeding.

Colonic Causes

  • Diverticular disease: Common in older adults, presents with painless, large-volume bleeding.
  • Colorectal cancer: Change in bowel habits, weight loss, and iron deficiency anemia are key features.
  • Inflammatory bowel disease (IBD): Chronic diarrhea, abdominal pain, and intermittent bleeding.
  • Colonic polyps: Often asymptomatic but can cause bleeding if large or ulcerated.
  • Ischemic colitis: Sudden onset of abdominal pain followed by bloody diarrhea, often in older adults with vascular risk factors.

Small Bowel Causes

  • Angiodysplasia: Occurs commonly in the elderly, often painless but can cause significant bleeding.
  • Meckel’s diverticulum: Typically presents in younger patients with painless, maroon-colored stools.
  • Crohn’s disease: Chronic diarrhea and weight loss, with possible bleeding episodes.

Vascular and Other Causes

  • Aortoenteric fistula: Rare but life-threatening cause, usually in patients with a history of aortic graft surgery.
  • Radiation proctitis: History of pelvic radiation, presents with bleeding, tenesmus, and diarrhea.
  • Coagulopathy: Patients on anticoagulants or with blood dyscrasias may present with spontaneous bleeding.
  • Infectious colitis: Associated with fever, abdominal pain, and diarrhea, often following recent travel or antibiotic use.

Key Points in History 🥼

Onset and Duration

  • Sudden onset: Suggests diverticular bleed, ischemic colitis, or aortoenteric fistula.
  • Chronic or recurrent: More likely IBD, colorectal cancer, or angiodysplasia.

Character of Blood

  • Bright red blood: Typically suggests lower sources like hemorrhoids or anal fissures.
  • Dark red or maroon blood: Often from diverticular disease or angiodysplasia.
  • Mixed with stool: Suggests a colonic source such as cancer or IBD.

Associated Symptoms

  • Painful defecation: Suggests anal fissure or hemorrhoids.
  • Abdominal pain: May point to IBD, ischemic colitis, or infectious colitis.
  • Systemic symptoms: Fever, weight loss, and night sweats may suggest IBD or malignancy.

Background

  • Past medical history: Look for IBD, previous polyps, diverticular disease, or a history of abdominal surgeries.
  • Drug history: Consider anticoagulants, NSAIDs, and recent antibiotics.
  • Family history: Especially relevant for colorectal cancer or IBD.
  • Social history: Recent travel may indicate infectious causes; alcohol use and liver disease may suggest varices.

Possible Investigations 🌡️

Laboratory Tests

  • Full blood count (FBC): To assess for anemia and potential infection.
  • Urea and electrolytes: To assess renal function, especially in the context of significant blood loss.
  • Coagulation profile: Important if the patient is on anticoagulants or has a coagulopathy.

Imaging

  • CT angiography: Useful in active bleeding to localize the source.
  • Colonoscopy: The investigation of choice for diagnosing the cause of lower GI bleeding.
  • Radionuclide scanning: Sometimes used when other imaging is inconclusive.

Endoscopic Techniques

  • Flexible sigmoidoscopy: Often used in the initial assessment if bleeding is suspected to be distal.
  • Upper GI endoscopy: To exclude upper GI sources if no lower GI cause is found.
  • Capsule endoscopy: May be useful for small bowel bleeding not identified on other imaging.

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Gastrointestinal