Trapping of a section of intestine in the subsequent section, always in the direction of peristalsis, towards the anus. The condition occurs most frequently in baby boys around the age of one year, seldom in adults. Symptoms are initially acute, caused by blockage of the intestine and interruption of blood supply to the affected part. Characteristic signs are fits of crying and restlessness, sometimes a little blood in the faeces, vomiting, and poor appetite. If the condition is neglected it can deteriorate into ileus, with all associated symptoms, and death of the affected section of the intestine. Examination reveals peristalsis, but a sausage-like swelling can be felt; an X-ray using a contrast medium shows up the intussusception. Sometimes the introduction of contrast medium via the anus has the happy side-effect of pushing back the invagination. If this does not occur, treatment is by surgical removal of the intussusception, along with any dead sections of intestine.