Intestine, disorders of

The intestine is subject to various structural abnormalities and to the effects of many infective organisms and parasites; it may also be affected by tumours and other disorders. Structural abnormalities may be present from birth (congenital) or may develop later. They cause blockage of the intestine (see intestine, blockage of) and include atresia, stenosis, and volvulus. In newborns, meconium (fetal intestinal contents) may block the intestine. Generalized inflammation of the intestine may result from viral or bacterial infections or from noninfectious causes, as in ulcerative colitis and Crohn’s disease. Gastroenteritis is the term commonly applied to inflammation of the stomach and intestines. Infection encompasses food poisoning, traveller’s diarrhoea, typhoid fever, cholera, amoebiasis, and giardiasis. Intestinal worm infestations include roundworms and tapeworms. Sometimes inflammation is localized, such as in appendicitis and diverticular disease. Tumours of the small intestine are rare, but noncancerous growths, lymphomas, and carcinoid tumours (causing carcinoid syndrome) occur. Tumours of the large intestine are common (see colon, cancer of; rectum, cancer of). Some forms of familial polyposis may progress to cancer. Impaired blood supply ( ischaemia) to the intestine may occur as a result of partial or complete obstruction of the arteries in the abdominal wall (from diseases such as atherosclerosis) or from the blood vessels being compressed or trapped, as in intussusception or hernias. Loss of blood supply may cause gangrene. Other disorders that affect the intestine include peptic ulcers, diverticulosis, malabsorption, coeliac disease, and irritable bowel syndrome.