The intestine extends from the stomach to the anus. The upper, small intestine (also called the small bowel) is narrow and about 20 feet long. It digests food and absorbs nutrients from digested food. The lower, large intestine (called the colon and the large bowel) is wider and about five feet long; it reabsorbs water from the digested foods and sends it back into the bloodstream.
Diseases, congenital defects or trauma that affect the way the small intestine absorbs nutrients or moves food through the intestinal tract may lead to transplantation. Symptoms of intestinal failure include persistent diarrhea, dehydration, muscle wasting, poor growth, frequent infections, weight loss, and fatigue.
The most common reason leading to transplantation is short bowel syndrome resulting from tumors, Chron’s and other inflammatory bowel diseases, congenital defects, trauma and other causes.
Small intestine transplantation can be performed in one of three ways: alone, in combination with the liver, or in combination with the liver, pancreas, stomach, duodenum or colon.
The large intestine is not necessary to sustain life, so it has been transplanted only in rare circumstances, and always in conjunction with the small intestine. This practice has been abandoned however, because the risk of infection is too high.
- The small intestine has an absorptive area of about 5,400 square yards due to folds in the intestinal wall, which contain small, finger-like projections called villi.
- Layers of smooth muscle surround the small intestine, and move its contents downward.
- The small intestine takes about six hours to complete the digestion of food, after which only water and indigestible substances are left.
- Most patients with intestinal failure can be supported on total parenteral nutrition (TPN), a procedure in which nutrients are provide directly into the bloodstream.
- The most common cause leading to transplantation is short bowel or short gut syndrome in which a large portion of the intestine has been removed because of disease or birth defect.
- Slightly more than 1,000 intestinal transplants — alone and with other organs — have been performed in the U.S. since the 1960s.
- About 200 people are now on the waiting list for new intestines or for intestines in combination with another organ.
- Intestine transplants usually involve a deceased donor, although a living donor can donate an intestinal segment.
- Small intestine transplants were first attempted in the 1960s and became successful in the 1980s.