Crohn’s disease (CD) may be classified into various types, depending on the location of symptoms. CD most commonly affects the small intestine (made up of the duodenum, jejunum and ileum) and the large intestine (cecum, colon and rectum). The various types of CD include:

• Ileocolitis. The most common form of CD, with symptoms occurring in both the small intestine’s ileum and the first part (cecum) of the large intestine. Symptoms include diarrhea, significant weight loss, and cramping or pain in the lower right or middle of the abdomen.
  
  
• Ileitis. When inflammation occurs in the ileum (also referred to as the “terminal ileum”). The symptoms are similar to those of ileocolitis, although fistulae and abscesses may also develop.
  
  
• Gastroduodenal Crohn’s disease. Affects the stomach and small intestine’s duodenum. Symptoms include loss of appetite, nausea, vomiting and weight loss. Vomiting may indicate an intestinal obstruction.
  
  
• Jejunoileitis. Inflammation of the jejunum, the largest part of the small intestine. Symptoms include diarrhea, abdominal pain and cramping. Malnutrition may occur, due to malabsorption by the jejunum, where most absorption of nutrients occurs. Fistulae may also develop.