A 69-year-old man is brought to emergency because of severe abdominal pain for the past 4 hours. He has a history of chronic atrial fibrillation. Abdominal examination shows mild diffuse tenderness to palpation. Fecal occult blood is positive. Laboratory studies show:
Hemoglobin 14 g/dL
WBC 12,000/μL
pH 7.2
pCO2 25 mm Hg
pO2 85 mm Hg
Which of the following is the most likely diagnosis?
Abdominal aortic aneurysm
Diverticulitis
Gastroenteritis
Ischemic colitis
Mesenteric ischemia
Perforated ulcer
