Differential Diagnosis for a Patient with Ulcerative Colitis Presenting with Diarrhea Followed by Absence of Bowel Movement and Abdominal Heaviness

• Single Most Likely Diagnosis:

  • Toxic Megacolon: This condition is a known complication of ulcerative colitis, especially in the setting of severe disease activity. The transition from diarrhea to an absence of bowel movements (obstruction) along with abdominal heaviness could indicate the development of toxic megacolon, which is a life-threatening condition requiring immediate medical attention.

• Other Likely Diagnoses:

  • Partial Intestinal Obstruction: This could be due to inflammation and scarring from chronic ulcerative colitis, leading to a narrowing of the intestinal lumen and subsequent obstruction.
  • Constipation: Although less common in ulcerative colitis patients who typically experience diarrhea, constipation can occur, especially if there's a significant reduction in disease activity or as a side effect of medications.
  • Medication Side Effects: Certain medications used to treat ulcerative colitis can cause constipation as a side effect.

• Do Not Miss Diagnoses:

  • Bowel Perforation: A serious and potentially life-threatening complication that can arise from toxic megacolon or severe ulcerative colitis. Symptoms can include severe abdominal pain, tenderness, and guarding.
  • Sepsis: Infection can complicate ulcerative colitis, especially in the setting of toxic megacolon or bowel perforation. Early recognition and treatment are crucial.
  • Colon Cancer: Although less likely in the acute setting, patients with long-standing ulcerative colitis are at an increased risk of developing colon cancer. Any new or changing symptoms should prompt consideration of this diagnosis.

• Rare Diagnoses:

  • Volvolus or Intussusception: These are rare causes of intestinal obstruction that could potentially occur in the setting of ulcerative colitis, although they are more commonly associated with other conditions.
  • Ischemic Colitis: Reduced blood flow to the colon can cause symptoms similar to ulcerative colitis, including abdominal pain and changes in bowel habits. It's a rare but important consideration, especially in patients with risk factors for vascular disease.