Why it's done

You may need parenteral nutrition for one of the following reasons:

• Cancer. Cancer of the digestive tract may cause an obstruction of the bowels, preventing adequate food intake. Cancer treatment, such as chemotherapy, may cause your body to poorly absorb nutrients.
• Crohn's disease. Crohn's disease is an inflammatory disease of the bowel that may cause pain, bowel narrowing and other symptoms that affect food intake and its digestion and absorption.
• Short bowel syndrome. In this condition, which can be present at birth or occur as the result of surgery that has removed a significant amount of small intestine, you don't have enough bowel to absorb enough of the nutrients you eat.
• Ischemic bowel disease. This may cause difficulties resulting from reduced blood flow to the bowel.
• Abnormal bowel function. This causes food you eat to have trouble moving through your intestines, resulting in a variety of symptoms that prevent enough food intake. Abnormal bowel function can occur due to surgical adhesions or abnormalities in bowel motility. These may be caused by radiation enteritis, neurological disorders and many other conditions.