Management of mechanical occlusion, particularly of the small intestine, has altered considerably over recent years, with a change of paradigm and the indication for surgery depending on the cause of the occlusion and any signs of entrapment or strangulation. It is therefore important today to make a positive diagnosis of mechanical occlusion, to assess its degree, its location and its cause, and to look for signs of entrapment and strangulation. Only computer tomography can provide the answers to these different questions. The aim of this paper is to provide a reminder of the CT signs that enable us to confirm diagnosis of the various aspects of mechanical occlusion of the stomach and duodenum, small intestine or colon, to emphasize and illustrate the diagnostic traps in CT and to set out the key points of a CT report of mechanical occlusion.