Blind loop syndrome, also known as stagnant loop syndrome, is a state that occurs when the normal bacterial flora of the small intestine proliferates to numbers that cause significant derangement to the normal physiological processes of digestion and absorption. In some cases of blind loop syndrome, overgrowth of pathogenic non-commensal bacteria has also been noted. It has long been understood that from birth, and throughout life, large amounts of bacteria reside symbiotically within animal gastrointestinal tracts such as the human gastrointestinal tract. The understanding of this gut flora has even led to novel treatments for bowel irregularity that utilize so called "probiotics" or good bacteria that aid in normal digestion. The problem of blind loop syndrome arises when the bacterial colonies residing in the upper gastrointestinal tract begin to grow out of control or are altered in their makeup thereby creating a burden on the normal physiological processes occurring in the small intestine. This results in problems, among others, of: vitamin B12 deficiency, fat malabsorption and steatorrhea, fat-soluble vitamin deficiencies and intestinal wall injury. Symptoms and signs Most of the symptoms of blind loop syndrome are non specific but nevertheless warrant the utmost attention. These include: Loss of appetite Nausea Flatulence Diarrhea Fullness after a meal Fatty stools (steatorrhea) Unintentional weight loss Generalised weakness As a result of the concomitant vitamin and mineral deficiencies that occur as a result of the malabsorption associated with blind loop syndrome patients with advanced cases should be investigated for: Vitamin B12 deficiency Folate deficiency Iron deficiency Vitamin E deficiency Causes Blind loop syndrome is a complication of surgical operations of the abdomen, as well as inflammatory bowel disease or scleroderma. Another cause is jejunoileal diverticula. Pathophysiology The overgrowth of bacteria in the small intestine is prevented by various mechanical and chemical factors which include the constant peristaltic movement of contents along the length of the gastrointestinal tract and the antibacterial properties of gastric secretions, pancreatic secretions and bile. It follows that a disruption of any of these factors could lead to bacterial overgrowth and indeed blind loop syndrome has been found to occur in persons with anatomical anomalies that result in stagnation. Blind loop syndrome has also been associated with achlorhydria, dysmotility, fistulae, and strictures. Chronic or high dose opioid therapy may contribute to blind loop syndrome by reducing gastric motility. Due to the disruption of digestive processes by the overgrowth of intestinal bacteria;