those who undergo intestinal resection, approximately 15% eventually develop small bowel syndrome (75% of those due to 1 large resection and 25% due to multiple separate intestinal resections). This surgery may be done for: Crohn's disease, an inflammatory disorder of the digestive tract Mesenteric ischemia, embolic or thrombotic events that may occur in the arteries or veins that supply or drain the intestines respectively, leading to disruption of blood supply to the intestines and ischemia. Volvulus, a twisting of the small intestine often caused by intestinal malrotation that quickly cuts off blood supply and leads to tissue death Tumors of the small intestine Radiation enteropathy, radiation injury to the small intestine, due to radiation therapy for cancer 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 Some children are also born with an abnormally short small intestine, known as congenital short bowel. Surgical complications, requiring re-surgery, are a common cause of small bowel syndrome, contributing up to 50% of cases based on some estimates. These surgical complications include internal hernias, volvuli, ischemia or profound hypotension. Pathophysiology The length of the small intestine can vary greatly, from as short as to as long as . On average it is about . Due to this variation it is recommended that following surgery the amount of bowel remaining be specified rather than the amount removed. Short bowel syndrome usually develops when there is less than 2 meters (6.6 feet) of the small intestine left to absorb sufficient nutrients. The resection of specific areas of the small bowel can lead to distinct symptoms in short bowel syndrome. The resection of the ileum leads to a malabsorption of vitamin B12, bile acids and the fat soluble vitamins A, D, E and K. Loss of the distal ileum also leads to loss of inhibitory hormones; leading to gastric hypersecretion, intestinal hypermotility (decreases in the intestinal transit time) leading to secretory diarrhea and macronutrient, micronutrient, vitamin and mineral deficiencies. Loss of the ileocecal valve leads to small intestinal bacterial overgrowth(SIBO) as bacterial flora normally found in the large intestines migrate proximally and colonize the small intestines leading to further malabsorption. SIBO leads to malabsorption as the bacteria colonizing the small intestine metabolize nutrients, directly competing with the intestinal absorption of nutrients. The bacteria colonizing the small intestines in SIBO