Differential Diagnosis for Non-C. diff Colitis

Given the statement "It's not C. diff colitis," we must consider a broad range of potential causes for colitis. The differential diagnosis can be organized into the following categories:

• Single Most Likely Diagnosis
  • Inflammatory Bowel Disease (IBD) - Crohn's disease or ulcerative colitis: These are common causes of colitis and should be considered first, especially in patients with chronic symptoms or those who do not have a clear infectious cause.
• Other Likely Diagnoses
  • Infectious colitis (e.g., Salmonella, Shigella, E. coli, Campylobacter): These pathogens can cause symptoms similar to C. difficile and are common in the community.
  • Ischemic colitis: This condition occurs when there is reduced blood flow to the colon and can present with sudden onset of abdominal pain and bloody diarrhea.
  • Microscopic colitis: This includes lymphocytic colitis and collagenous colitis, which are characterized by chronic watery diarrhea without visible blood.
• Do Not Miss Diagnoses
  • Neutropenic colitis: This is a potentially life-threatening condition that occurs in neutropenic patients, often those undergoing chemotherapy.
  • Radiation colitis: Patients with a history of radiation therapy to the abdominal area are at risk.
  • Fulminant colitis: Although this could be due to C. difficile, other causes like IBD or infectious agents should be considered, as the management and prognosis can differ significantly.
• Rare Diagnoses
  • Behçet's disease: A form of vasculitis that can cause colitis among other symptoms.
  • Eosinophilic colitis: Part of the eosinophilic gastrointestinal disorders, which are characterized by eosinophilic infiltration of the gastrointestinal tract.
  • Allergic colitis: More commonly seen in infants but can occur in adults, often related to food allergies.

Each of these diagnoses has a distinct set of clinical features, diagnostic criteria, and management strategies. A thorough history, physical examination, laboratory tests, and sometimes endoscopy are necessary to differentiate among them.