Differential Diagnosis for a 21-year-old Woman with Abdominal Pain, Diarrhea, Hematochezia, and Negative Celiac Test

• Single Most Likely Diagnosis
  • Inflammatory Bowel Disease (IBD), specifically Ulcerative Colitis (UC): This condition is characterized by chronic inflammation and ulceration of the colon, leading to symptoms such as abdominal pain, diarrhea, and hematochezia. The negative celiac test helps to rule out celiac disease, making UC a more likely diagnosis given the patient's symptoms.
• Other Likely Diagnoses
  • Crohn's Disease: Another form of IBD, Crohn's disease can affect any part of the gastrointestinal tract and presents with similar symptoms to UC, including abdominal pain, diarrhea, and hematochezia.
  • Irritable Bowel Syndrome (IBS): Although IBS does not typically cause hematochezia, a subset of patients with IBS may experience rectal bleeding, and the condition is common enough to be considered in the differential diagnosis.
  • Infectious Colitis: Bacterial, viral, or parasitic infections can cause colitis, leading to symptoms such as abdominal pain, diarrhea, and hematochezia.
• Do Not Miss Diagnoses
  • Intussusception: A condition where a part of the intestine telescopes into another, intussusception can cause abdominal pain, diarrhea, and hematochezia. It is a medical emergency that requires prompt diagnosis and treatment.
  • Colon Cancer: Although rare in young adults, colon cancer can present with abdominal pain, diarrhea, and hematochezia. It is crucial to rule out this diagnosis, especially if there is a family history or other risk factors.
  • Ischemic Colitis: Reduced blood flow to the colon can cause ischemic colitis, leading to abdominal pain, diarrhea, and potentially hematochezia. This condition can be life-threatening if not promptly diagnosed and treated.
• Rare Diagnoses
  • Ehlers-Danlos Syndrome: A genetic disorder that can affect the gastrointestinal tract, leading to symptoms such as abdominal pain and gastrointestinal bleeding.
  • Behçet's Disease: A rare condition characterized by inflammation of blood vessels, which can affect the gastrointestinal tract and cause symptoms such as abdominal pain, diarrhea, and hematochezia.
  • Gastrointestinal Lymphoma: A type of cancer that affects the immune cells in the gastrointestinal tract, which can present with a range of symptoms including abdominal pain, diarrhea, and hematochezia.