Gastrointestinal tract
The small intestine begins at the duodenum and is a tubular structure, usually between 6 and 7 m long. Its mucosal area in an adult human is about 30 m. Its main function is to absorb the products of digestion (including carbohydrates, proteins, lipids, and vitamins) into the bloodstream. There are three major divisions:
Short bowel syndrome
Short bowel syndrome (SBS, or simply short gut) is a malabsorption disorder caused by a lack of functional small intestine. The primary symptom is diarrhea, which can result in dehydration, malnutrition, and weight loss. Other symptoms may include bloating, heartburn, feeling tired, lactose intolerance, and foul smelling stool. Complications can include anemia and kidney stones.
Most cases are due to the surgical removal of a large portion of the small intestine. This is most often required due to Crohn's disease in adults and necrotising enterocolitis in young children. Other causes include damage to the small intestine from other means and being born with an abnormally short intestine. It usually does not develop until less than of the normally small intestine remains.
Treatment may include a specific diet, medications, or surgery. The diet may include slightly salty and slightly sweet liquids, vitamin and mineral supplements, small frequent meals, and the avoidance of high fat food. Occasionally nutrients need to be given through an intravenous line, known as parenteral nutrition. Medications used may include antibiotics, antacids, loperamide, teduglutide, and growth hormone. Different types of surgery, including an intestinal transplant, may help some people.
Short bowel syndrome newly occurs in about three per million people each year. There are estimated to be about 15,000 people with the condition in the United States. It is classified as a rare disease by the European Medicines Agency. Outcomes depend on the amount of bowel remaining and whether or not the small bowel remains connected with the large bowel.