Colonic Ileus

This 77-year-old man presented with abdominal pain and distention. The serum potassium level was 2.6 mmol per liter. Mechanical obstruction was excluded. A 77-year-old man with a history of hypertension, diabetes mellitus, and seizure disorder presented to the emergency room with abdominal pain and distention of approximately two to three days' duration. The patient reported no nausea, vomiting, or diarrhea. On physical examination, he had diffuse abdominal distention without guarding or rebound tenderness. Laboratory studies were unremarkable except for hypokalemia (serum potassium level, 2.6 mmol per liter). Abdominal radiography (Panel A) and computed tomography (CT) (Panel B) demonstrated marked colonic dilatation. Mechanical obstruction was excluded by the presence of air in the rectosigmoid, as shown on the CT scan, and a diagnosis . . .