A 34-year-old man with a history of ulcerative colitis presents to the emergency department with severe abdominal pain, fever, and worsening bloody diarrhea. He reports poor adherence to his maintenance medications. Temperature is 39.2°C (102.6°F), blood pressure is 96/58 mm Hg, pulse is 124/min, and respiratory rate is 22/min. Physical examination reveals abdominal distention and diffuse tenderness to palpation. Laboratory studies show a leukocyte count of 21,000/mm³. Abdominal radiography demonstrates marked colonic dilation.
Which of the following is the most likely diagnosis?
The correct answer is:
D: Toxic megacolon.
This patient has severe ulcerative colitis complicated by systemic toxicity and marked colonic dilation. Toxic megacolon is a life-threatening complication characterized by severe inflammation, colonic paralysis, and risk of perforation. Prompt recognition and aggressive treatment are essential.
Answer choice A: Acute appendicitis, is incorrect.
Appendicitis generally causes localized right lower quadrant pain rather than severe colitis and diffuse colonic dilation.
Answer choice B: Crohn disease flare, is incorrect.
Although inflammatory bowel disease can flare, toxic megacolon is classically associated with severe ulcerative colitis.
Answer choice C: Small bowel obstruction, is incorrect.
Small bowel obstruction causes vomiting and dilated small bowel loops rather than severe bloody diarrhea and colonic dilation.
Answer choice E: Viral gastroenteritis, is incorrect.
Viral gastroenteritis does not cause toxic systemic illness with massive colonic dilation.
Key Learning Point
Toxic megacolon is a life-threatening complication of severe ulcerative colitis characterized by systemic toxicity and colonic dilation.
