text: Small intestine cancer Developmental, congenital or genetic conditions
  Duodenal (intestinal) atresia
  Hirschsprung's disease
  Meckel's diverticulum
  Pyloric stenosis
  Pancreas divisum
  Ectopic pancreas
  Enteric duplication cyst
  Situs inversus
  Cystic fibrosis
  Malrotation
  Persistent urachus
  Omphalocele
  Gastroschisis
  Disaccharidase (lactase) deficiencies
  Primary bile acid malabsorption
  Gardner syndrome
  Familial adenomatous polyposis syndrome (FAP)
  Other conditions
  Crohn's disease, and the more general inflammatory bowel disease
  Typhlitis (neutropenic colitis in the immunosuppressed
  Coeliac disease (sprue or non-tropical sprue)
  Mesenteric ischemia
  Embolus or thrombus of the superior mesenteric artery or the superior mesenteric vein
  Arteriovenous malformation
  Gastric dumping syndrome
  Irritable bowel syndrome
  Duodenal (peptic) ulcers
  Gastrointestinal perforation
  Hyperthyroidism
  Diverticulitis
  Radiation enterocolitis
  Mesenteric cysts
  Peritoneal Infection
  Sclerosing retroperitonitis
  Small intestinal bacterial overgrowth
  Endometriosis
  Other animals
  The small intestine is found in all tetrapods and also in teleosts, although its form and length vary enormously between species. In teleosts, it is relatively short, typically around one and a half times the length of the fish's body. It commonly has a number of pyloric caeca, small pouch-like structures along its length that help to increase the overall surface area of the organ for digesting food. There is no ileocaecal valve in teleosts, with the boundary between the small intestine and the rectum being marked only by the end of the digestive epithelium.