Short bowel syndrome
|Short bowel syndrome|
Resected diseased ileum.
|Classification and external resources|
Short bowel syndrome (SBS, also short gut syndrome or simply short gut) is a malabsorption disorder caused by the surgical removal of the small intestine, or rarely due to the complete dysfunction of a large segment of bowel. Most cases are acquired, although some children are born with a congenital short bowel. It usually does not develop unless more than two thirds of the small intestine have been removed. SBS has been designated a rare disease by the EMA, and is eligible for orphan drug designation according to the U.S. Food and Drug Administration (FDA). There are roughly 3,500 adults and 9,000 children with SBS in the USA alone.
Signs and symptoms
The symptoms of short bowel syndrome can include:
- Abdominal pain
- Diarrhea and steatorrhea (oily or sticky stool, which can be malodorous)
- Fluid depletion
- Weight loss and malnutrition
Patients with short bowel syndrome may have complications caused by malabsorption of vitamins and minerals, such as deficiencies in vitamins A, D, E, K, B9 (folic acid), and B12, calcium, magnesium, iron, and zinc. These may appear as anemia, hyperkeratosis (scaling of the skin), easy bruising, muscle spasms, poor blood clotting, and bone pain.
Short bowel syndrome in adults and children is usually caused by surgery for:
- Crohn's disease, an inflammatory disorder of the digestive tract
- Volvulus, a spontaneous twisting of the small intestine that cuts off the blood supply and leads to tissue death
- Tumors of the small intestine
- Injury or trauma to the small intestine
- Necrotizing enterocolitis (premature newborn)
- Bypass surgery to treat obesity
- Surgery to remove diseases or damaged portion of the small intestine
In healthy adults, the small intestine has an average length of approximately 6 meters (19.7 feet). Short bowel syndrome usually develops when there is less than 2 meters (6.6 feet) of the small intestine left to absorb sufficient nutrients.
Short bowel syndrome caused by the surgical removal of a portion of the bowel may be a temporary condition, due to the adaptive property of the small intestine.
In a process called intestinal adaptation, physiological changes to the remaining portion of the small intestine occur to increase its absorptive capacity. These changes include:
- Enlargement and lengthening of the villi found in the lining
- Increase in the diameter of the small intestine
- Slow down in peristalsis or movement of food through the small intestine
Symptoms of short bowel syndrome are usually addressed with medication. These include:
- Anti-diarrheal medicine (e.g. loperamide, codeine)
- Vitamin, mineral supplements and L-glutamine powder mixed with water
- H2 blocker and proton pump inhibitors to reduce stomach acid
- Lactase supplement (to improve the bloating and diarrhoea associated with lactose intolerance)
In 2004, the USFDA approved a therapy that reduces the frequency and volume of total parenteral nutrition (TPN), comprising: NutreStore (oral solution of glutamine) and Zorbtive (growth hormone, of recombinant DNA origin, for injection) together with a specialized oral diet. In 2012, an advisory panel to the USFDA voted unanimously to approve for treatment of SBS the agent teduglutide, a glucagon-like peptide-2 analog developed by NPS Pharmaceuticals, who intend to market the agent in the United States under the brandname Gattex. Teduglutide had been previously approved for use in Europe and is marketed under the brand Revestive by Nycomed.
Surgical procedures to lengthen dilated bowel include the Bianchi procedure, where the bowel is cut in half and one end is sewn to the other, and a newer procedure called serial transverse enteroplasty (STEP), where the bowel is cut and stapled in a zigzag pattern. Heung Bae Kim, MD, and Tom Jaksic, MD, both of Children's Hospital Boston, devised the STEP procedure in the early 2000s. The procedure lengthens the bowel of children with SBS and may allow children to avoid the need for intestinal transplantation. As of June 2009, Kim and Jaksic have performed 18 STEP procedures. The Bianchi and STEP procedures are usually performed by pediatric surgeons at quaternary hospitals who specialize in small bowel surgery.
There is no cure for short bowel syndrome except transplant. In newborn infants, the 4-year survival rate on parenteral nutrition is approximately 70%. In newborn infants with less than 10% of expected intestinal length, 5 year survival is approximately 20%. Some studies suggest that much of the mortality is due to a complication of the total parenteral nutrition (TPN), especially chronic liver disease. Much hope is vested in Omegaven, a type of lipid TPN feed, in which recent case reports suggest the risk of liver disease is much lower.
Although promising, small intestine transplant has a mixed success rate, with postoperative mortality rate of up to 30%. One-year and 4-year survival rate are 90% and 60%, respectively.
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- Short Bowel Syndrome, from Children's Hospital Boston
- About Short Bowel Syndrome, from Children's Hospital Boston
- The Center for Advanced Intestinal Rehabilitation at Children's Hospital Boston
- Better Health Channel - Short Bowel Syndrome
- Health In Plain English - Short Bowel Syndrome
- National Digestive Diseases Information Clearinghouse - Short Bowel Syndrome