Differential Diagnosis for Diarrhea

The differential diagnosis for diarrhea is broad and can be categorized based on the likelihood and potential impact of missing a diagnosis. Here's a structured approach:

• Single Most Likely Diagnosis

  • Viral gastroenteritis: This is often the most common cause of diarrhea, especially in children and young adults, due to its highly contagious nature and the ease with which viral infections can spread.

• Other Likely Diagnoses

  • Bacterial gastroenteritis (e.g., Salmonella, E. coli, Campylobacter): These infections are common and can be contracted through contaminated food or water.
  • Food poisoning: Similar to bacterial gastroenteritis, food poisoning can cause sudden onset of diarrhea and is often related to the consumption of spoiled or contaminated food.
  • Lactose intolerance or other dietary intolerances: In individuals with lactose intolerance or other dietary intolerances, the ingestion of lactose or other problematic substances can lead to diarrhea.
  • Inflammatory bowel disease (IBD): Conditions like Crohn's disease and ulcerative colitis can cause chronic diarrhea, among other symptoms.
  • Irritable bowel syndrome (IBS): A functional gastrointestinal disorder that can cause diarrhea, often accompanied by abdominal pain and changes in bowel habits.

• Do Not Miss Diagnoses

  • Clostridioides difficile (C. diff) infection: This bacterial infection can cause severe diarrhea and is particularly dangerous in hospitalized patients or those with compromised immune systems.
  • Giardiasis: An intestinal infection caused by the parasite Giardia lamblia, which can lead to severe and prolonged diarrhea if not treated.
  • Cholera: Although rare in many parts of the world, cholera is a highly infectious disease that causes severe, watery diarrhea and can lead to rapid dehydration and death if not promptly treated.
  • Intestinal ischemia: Reduced blood flow to the intestines can cause severe abdominal pain and diarrhea, and is a medical emergency.

• Rare Diagnoses

  • Whipple's disease: A rare, systemic bacterial infection that can cause diarrhea, among other symptoms like weight loss and joint pain.
  • Tropical sprue: A rare condition that affects the intestines and can cause chronic diarrhea, typically seen in people who live in or visit tropical areas.
  • Microscopic colitis: An inflammatory condition of the colon that can cause chronic, watery diarrhea.
  • Eosinophilic gastroenteritis: A rare condition characterized by the presence of eosinophils in the gastrointestinal tract, leading to symptoms like diarrhea, abdominal pain, and weight loss.

Each of these diagnoses has a distinct set of causes, risk factors, and clinical presentations, and a thorough medical history, physical examination, and diagnostic testing are often necessary to determine the underlying cause of diarrhea in a given patient.