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Causes
By Mayo Clinic staff
Although digestion begins in your mouth, the real work of breaking down and absorbing nutrients takes place in your small intestine, the longest section of your digestive tract measuring about 20 feet (6.1 meters). Connecting your stomach and large intestine, your small intestine is where food mixes with digestive juices from your stomach, pancreas, liver and gallbladder, and where small nutrient molecules — amino acids from proteins, monosaccharides from carbohydrates and most fats — are absorbed into your bloodstream.
Unlike your large intestine (colon), which has billions of bacteria to help break down indigestible fiber, your small intestine normally contains relatively few microorganisms. Because your small intestine is rich in enzymes, it doesn't need the enzymatic action of bacteria. In fact, stomach acid and secretions from your liver and pancreas actually act as antibacterial agents. What's more, the strong muscular contractions (peristalsis) that propel food through your small intestine prevent bacteria from colonizing there.
But in blind loop syndrome, food can't move through the bypassed section of intestine, and the stagnant food becomes an ideal breeding ground for microorganisms — a condition called bacterial overgrowth syndrome. The bacteria may produce toxins as well as interfere with the absorption of nutrients. The greater the length of small bowel involved in the blind loop, the greater the degree of bacterial overgrowth.
What triggers blind loop syndrome
Blind loop syndrome can be caused by:
- Complications of abdominal surgery. Procedures that may inadvertently cause a blind loop include gastric bypass surgery for obesity, such as the Roux-en-Y procedure, and surgical gastrectomy to treat peptic ulcers and stomach cancer, such as the Billroth II.
- Structural abnormalities of the small intestine. Structural problems in and around your small intestine may lead to bacterial overgrowth. Examples of such defects — which may be inherited or may result from surgery, infection or injury — include bands of scar tissue (intestinal adhesions) on the outside of the bowel and small, bulging pouches of tissue that protrude through the intestinal wall (diverticulosis).
- Bacterial overgrowth associated with certain medical conditions. Health problems that can slow the rate at which food moves through the intestine — including Crohn's disease, scleroderma and diabetes — are associated with an increased risk of a blind loop.
- Turnage RH, et al. Abdominal wall, umbilicus, peritoneum, mesenteries, omentum, and retroperitoneum. In: Townsend CM, et al. Sabiston Textbook of Surgery. 18th ed. Philadelphia, Pa.: Saunders Elsevier; 2007. http://www.mdconsult.com/das/book/body/164856770-3/902155171/1565/469.html#4-u1.0-B978-1-4160-3675-3..50052-6--cesec137_2746. Accessed Oct. 13, 2009.
- Vanderhoof JA, et al. Pathogenesis, clinical manifestations, and diagnosis of bacterial overgrowth. http://www.uptodate.com/home/index.html. Accessed Oct. 13, 2009.
- Bacterial overgrowth syndrome: Malabsorption syndromes. The Merck Manuals: The Merck Manual for Healthcare Professionals. http://www.merck.com/mmpe/print/sec02/ch017/ch017b.html. Accessed Oct. 13, 2009.
- Vanderhoof JA, et al. Treatment of bacterial overgrowth. http://www.uptodate.com/home/index.html. Accessed Oct. 13, 2009.
- Kahn E, et al. Anatomy, histology, embryology, and developmental anomalies of the small and large intestine. In: Feldman M, et al. Sleisenger & Fordtran's Gastrointestinal and Liver Disease. 8th ed. Philadelphia, Pa.: Saunders Elsevier; 2006. http://www.mdconsult.com/das/book/body/164856770-5/902188062/1389/733.html#4-u1.0-B1-4160-0245-6..50104-9--cesec7_4663. Accessed Oct. 13, 2009.
- Picco MF (expert opinion). Mayo Clinic, Rochester, Minn. Oct. 21, 2009.
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