Computed tomography (CT) scan of the abdomen of a 57 year old male patient with a massively dilated colon (large intestine) that is not caused by a mechanical obstruction. This is known as Ogilvie syndrome or acute colonic pseudo-obstruction (ACPO) and is thought to be caused by abnormalities in the autonomic nervous system that controls the movements of the colon. It is most often seen in patients with underlying diseases or those that have recently undergone surgery.