Colitis Differential Diagnosis

The differential diagnosis for colitis can be organized into the following categories:

• Single Most Likely Diagnosis
  • Ulcerative Colitis (UC): This is a common cause of colitis, characterized by chronic inflammation and ulceration of the colon's inner lining, often presenting with bloody diarrhea, abdominal pain, and weight loss.
• Other Likely Diagnoses
  • Crohn's Disease: A type of inflammatory bowel disease (IBD) that can affect any part of the gastrointestinal tract, causing symptoms similar to UC, but often with a more unpredictable course and potential involvement of the small intestine.
  • Infectious Colitis (e.g., Clostridioides difficile, Salmonella, Shigella): Bacterial infections can cause acute colitis, presenting with sudden onset of diarrhea, abdominal cramps, and fever.
  • Ischemic Colitis: Reduced blood flow to the colon can cause inflammation and damage, often presenting with sudden onset of abdominal pain and bloody diarrhea, particularly in older adults.
• Do Not Miss Diagnoses
  • Clostridioides difficile Infection: While not the most common cause, C. difficile can lead to severe, life-threatening colitis if not promptly treated, especially in hospitalized or immunocompromised patients.
  • Neutropenic Colitis: Occurs in patients with significantly low neutrophil counts, often due to chemotherapy or bone marrow transplantation, and can rapidly progress to severe complications if not recognized early.
  • Diverticulitis: Inflammation of a diverticulum in the colon wall can mimic colitis and requires prompt treatment to prevent complications like abscess formation or perforation.
• Rare Diagnoses
  • Microscopic Colitis: Includes lymphocytic and collagenous colitis, characterized by microscopic inflammation of the colon lining, often presenting with chronic, watery diarrhea.
  • Eosinophilic Colitis: A rare condition involving eosinophilic infiltration of the colon wall, which can be associated with eosinophilic gastrointestinal disorders or parasitic infections.
  • Radiation Colitis: Inflammation and damage to the colon lining following radiation therapy, particularly for pelvic malignancies, can lead to chronic symptoms and complications.
  • Behçet's Disease: A rare, multisystem disorder that can cause colitis among other symptoms, including oral and genital ulcers and eye inflammation.