Differential Diagnosis for IBS

The following differential diagnosis is organized into categories to help guide the thought process:

• Single Most Likely Diagnosis

  • Irritable Bowel Syndrome (IBS) itself: This is the most likely diagnosis, as the symptoms presented are classic for IBS, including abdominal pain, changes in bowel habits, and the absence of other alarming symptoms.

• Other Likely Diagnoses

  • Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis can present similarly to IBS but are distinguished by the presence of inflammation on biopsy and often more severe symptoms.
  • Functional dyspepsia: Overlapping symptoms with IBS, particularly in the upper gastrointestinal tract, can make functional dyspepsia a consideration.
  • Celiac disease: An autoimmune reaction to gluten can cause gastrointestinal symptoms similar to IBS, and it's essential to rule out celiac disease with serological tests and intestinal biopsy if suspected.

• Do Not Miss Diagnoses

  • Colon cancer: Although less common in younger populations, colon cancer can present with changes in bowel habits and abdominal pain, making it crucial to consider, especially in patients over 50 or with a family history.
  • Gastrointestinal infections: Certain infections, such as giardiasis or bacterial overgrowth, can mimic IBS symptoms and require specific treatment.
  • Ischemic bowel disease: Reduced blood flow to the intestines can cause abdominal pain and changes in bowel habits, especially in older patients or those with vascular disease.

• Rare Diagnoses

  • Microscopic colitis: A condition characterized by inflammation of the colon that can only be diagnosed by biopsy, presenting with chronic, watery diarrhea.
  • Eosinophilic gastroenteritis: A rare condition involving eosinophilic infiltration of the gastrointestinal tract, which can cause a variety of symptoms including abdominal pain and changes in bowel habits.
  • Mastocytic enterocolitis: Characterized by an increased number of mast cells in the gastrointestinal mucosa, leading to symptoms that can overlap with IBS, such as abdominal pain and diarrhea.

Each of these diagnoses has a brief justification based on the similarity of symptoms to IBS and the importance of ruling out more severe conditions to ensure proper management and treatment.