How the Digestive System is Involved in Crohn Disease

Crohn disease is a chronic inflammation of the digestive tract. Any part of the digestive tract from the mouth to the anus can be involved, although it most commonly affects the lower part of the small intestine called the ileum and the beginning of the large intestine called the cecum. The inflammation may extend deep into the tissues of the organ that is affected. The inflammation may cause pain in the abdomen and may make the intestines empty frequently, resulting in diarrhea. Other symptoms include bloating, constipation, pain or bleeding with a bowel movement, or a urinary tract infection or a vaginal infection.
 
In addition, the following complications may occur: blockage in the intestine due to thickening of the intestinal walls; ulcers or fissures may tunnel through the affected area into surrounding areas (eg, bladder, vagina, skin), and fistulas (communication between the intestine and other adjacent organs) may develop. Thickening of the wall due to acute inflammation may narrow the lumen of the small intestine. Scar tissue resulting from the healing process may also lead to a narrowed bowel, and strictures are often present. Nutritional complications are common in Crohn disease. Protein, calorie, and vitamin deficiencies may be due to inadequate dietary intake, loss of protein in the intestine, or poor absorption. Depending on what part of the intestine is affected, the symptoms and complications may differ. See Crohn Disease for more information.