Differential Diagnosis for Constipation, Fever, Inflamed Colon, and Rectal Ulcers

• Single Most Likely Diagnosis
  • Inflammatory Bowel Disease (IBD) - Ulcerative Colitis: This condition is characterized by chronic inflammation and ulcers in the colon, which matches the sigmoidoscopy findings. The symptoms of constipation, fever, and inflamed colon are also consistent with an acute flare of ulcerative colitis.
• Other Likely Diagnoses
  • Infectious Colitis: Bacterial, viral, or parasitic infections can cause inflammation of the colon, leading to symptoms like fever, constipation, and rectal ulcers. Common pathogens include Salmonella, Shigella, and Campylobacter.
  • Diverticulitis: Inflammation of the diverticula in the colon can cause fever, constipation, and abdominal pain. While it typically affects the sigmoid colon, it might not directly cause rectal ulcers unless there's an associated complication.
• Do Not Miss Diagnoses
  • Ischemic Colitis: Reduced blood flow to the colon can cause inflammation and potentially lead to ulcers. This condition is more common in older adults and can be precipitated by factors like dehydration, heart failure, or vascular disease. Missing this diagnosis could lead to severe complications, including gangrene and perforation.
  • Clostridioides difficile (C. diff) Infection: This bacterial infection can cause severe diarrhea but also constipation in some cases, along with fever and colonic inflammation. It's particularly dangerous because it can lead to toxic megacolon and sepsis if not treated promptly.
• Rare Diagnoses
  • Crohn's Disease: While it's a form of IBD like ulcerative colitis, Crohn's disease can affect any part of the gastrointestinal tract and might present with similar symptoms. However, it's less likely to cause continuous inflammation limited to the colon and rectum.
  • Behçet's Disease: A rare condition characterized by inflammation of blood vessels throughout the body, which can lead to ulcers in the mouth, genitals, and intestines. Intestinal involvement can mimic IBD, but it's much less common and typically associated with other systemic symptoms.