Differential Diagnosis for Diarrhea with Blood in Stool, Anemia, and Spondyloarthropathy

• Single Most Likely Diagnosis

  • Inflammatory Bowel Disease (IBD), specifically Ulcerative Colitis or Crohn's Disease: These conditions are known for causing chronic diarrhea, which can be bloody, leading to anemia due to chronic blood loss. They are also associated with extraintestinal manifestations, including spondyloarthropathies like ankylosing spondylitis and other forms of spondyloarthritis.

• Other Likely Diagnoses

  • Reactivate Arthritis (ReA): This form of arthritis can occur after certain bacterial infections, including gastrointestinal infections. It can present with diarrhea, arthritis, and sometimes eye inflammation. While less directly linked to anemia, the chronic nature of the disease and potential for gastrointestinal involvement could contribute to anemia.
  • Enteropathic Arthritis: This condition is directly associated with inflammatory bowel disease but can also occur independently. It involves joint inflammation and can be accompanied by gastrointestinal symptoms, including bloody diarrhea, which could lead to anemia.

• Do Not Miss Diagnoses

  • Infectious Colitis: Certain infections (e.g., Salmonella, Shigella, Campylobacter, or Clostridioides difficile) can cause bloody diarrhea and, if severe or prolonged, could lead to anemia. Some of these infections can also trigger reactive arthritis, which might explain the spondyloarthropathy.
  • Ischemic Colitis: Reduced blood flow to the colon can cause bloody diarrhea and abdominal pain. While less commonly associated with spondyloarthropathy directly, the systemic nature of vascular diseases could potentially link to rheumatologic conditions indirectly.

• Rare Diagnoses

  • Behçet's Disease: A rare condition that can cause a wide range of symptoms, including mouth sores, genital sores, skin rashes, and eye inflammation. Gastrointestinal involvement can lead to bloody diarrhea, and the disease can also cause arthritis, potentially fitting the described symptoms.
  • Whipple's Disease: A rare, systemic bacterial infection that can cause malabsorption, leading to diarrhea, weight loss, and potentially anemia. Joint pain can also be a symptom, although it's less commonly associated with spondyloarthropathy directly.