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Common Causes of Bloody, Chronic Diarrhea

Common Causes of Bloody, Chronic Diarrhea
Diagnosis
Clinical Features
Laboratory/Imaging Testing
Initial Management

Infectious colitis
  • Possible presence of blood and/or mucus in stool 
  • Possible fever and/or abdominal pain 
  • Exposure to undercooked meat/fish, unpasteurized dairy products or fruit juices, or contaminated water 
  • Childcare center attendance
  • Supportive care in most cases
  • If immunocompromised or severe refractory diarrhea, may consider alternative treatment and/or Infectious Diseases consult 

Inflammatory bowel disease (IBD)
  • Possible blood in stool (blood is more common in colitis) 
  • Stooling urgency and frequency 
  • Nocturnal stools
  • Abdominal pain
  • Fatigue 
  • Weight loss
  • ESR and CRP elevation
  • CBC: Iron deficiency anemia, reactive thrombocytosis
  • CMP: Hypoalbuminemia, electrolyte abnormalities 
  • Fecal calprotectin elevated (often > 250 µg/g) 
  • Infectious stool studies negative
  • Imaging may show bowel wall thickening 
  • PRBCs if Hgb <7 g/dL or <8 g/dL with symptoms (fatigue, dizziness, tachycardia) 
  • IV fluids if signs of dehydration or significant diarrhea 
  • Pain management: avoid opioids and NSAIDs. Prefer acetaminophen as needed. 
  • Consult GI specialists for EGD/colonoscopy with biopsies to confirm diagnosis and provide further management  
    • Treatment may involve corticosteroids and/or immunosuppressants 

Food protein-induced allergic proctocolitis (FPIAP)
  • Most common triggers are cow’s milk and soy proteins 
  • May have diarrhea (+/- blood), vomiting, growth failure
  • Often presents within the first few months of life but can persist up to age 3 
  • Diagnosed clinically; labs and imaging are generally not needed
  • Guaiac fecal occult blood test (gFOBT) may be positive 
  • CBC: Possible iron deficiency anemia 
  • IV fluids if signs of dehydration or significant diarrhea
  • Dietary elimination of cow’s milk +/- soy (for at least 2 weeks)
  • Consider hydrolyzed or elemental formula
  • Consider Nutrition consult
  • Generally resolves by 1-2 years of age. Consider rechallenge of food protein ~1 year of age. 
References: 
1. Zella GC, Israel EJ. Chronic diarrhea in children. Pediatr Rev. 2012;33(5):207-218. 
2. Martin MG, Thiagarajah JR. Approach to chronic diarrhea in children >6 months in resource-abundant settings. In: Connor RF, ed. UpToDate. Wolters Kluwer. Accessed May 2026.

These pathways do not establish a standard of care to be followed in every case. It is recognized that each case is different, and those individuals involved in providing health care are expected to use their judgment in determining what is in the best interests of the patient based on the circumstances existing at the time. It is impossible to anticipate all possible situations that may exist and to prepare a pathway for each. Accordingly, these pathways should guide care with the understanding that departures from them may be required at times.

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Chronic Diarrhea
Common Causes of Bloody, Chronic Diarrhea