Differential Diagnosis for Diarrhea

The following is a differential diagnosis for a patient presenting with diarrhea, categorized for clarity and emphasis on potential severity.

• Single Most Likely Diagnosis
  • Viral Gastroenteritis: This is often the most common cause of diarrhea, typically presenting with a sudden onset of symptoms including diarrhea, vomiting, and abdominal cramps. The justification for this being the single most likely diagnosis is its high prevalence and the fact that it can be caused by a variety of common viruses such as norovirus and rotavirus.
• Other Likely Diagnoses
  • Bacterial Gastroenteritis: Caused by bacteria such as Salmonella, Shigella, and Campylobacter, this condition can present similarly to viral gastroenteritis but may have a more severe course and potentially lead to complications like bacteremia.
  • Food Poisoning: This can result from consuming contaminated or spoiled food, leading to symptoms of diarrhea, vomiting, and abdominal pain. The timing and context of the symptoms (e.g., recent travel, eating undercooked meat) can help differentiate this from other causes.
  • Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis can cause chronic diarrhea, often accompanied by blood in the stool, weight loss, and abdominal pain.
• 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 who have recently used antibiotics. Missing this diagnosis can lead to severe complications, including pseudomembranous colitis and toxic megacolon.
  • Intestinal Ischemia: Although less common, this condition involves a reduction in blood flow to the intestines and can present with sudden onset of abdominal pain and diarrhea. It is a medical emergency that requires prompt intervention.
• Rare Diagnoses
  • Whipple's Disease: A rare, systemic bacterial infection that can cause diarrhea, weight loss, and abdominal pain, among other symptoms. It is often diagnosed through small intestine biopsy.
  • Giardiasis: An intestinal infection caused by the parasite Giardia lamblia, which can lead to chronic diarrhea, particularly in individuals who have traveled to areas with poor sanitation or have been exposed to contaminated water.
  • Lactose Intolerance or Other Carbohydrate Malabsorption: Conditions where the body is unable to digest certain sugars, leading to bloating, gas, and diarrhea after consuming these substances.

Each of these diagnoses has distinct characteristics and potential consequences, emphasizing the importance of a thorough diagnostic approach to manage diarrhea effectively and prevent serious outcomes.