Risks of Gastric Bypass Roux-en-Y Nutritional Deficiencies and Dumping Syndrome "Dumping syndrome." When stomach contents are literally "dumped" rapidly into the small intestine. Sometimes triggered by too much sugar or large amounts of food. Dumping syndrome doesn't pose a health risk, but its symptoms aren't fun: nausea, weakness, sweating, faintness, and diarrhea. Some patients can prevent dumping syndrome by avoiding sweets after surgery. Follow-up operations. Up to 20% of patients need follow-up operations to correct problems such as hernias. Gallstones. Up to 30% of patients develop gallstones after losing weight. You can reduce the risk of gallstones by taking bile salts for 6 months following surgery. Leakage of the connection between the pouch and the intestine. This is very rare, but potentially dangerous. Diminished effectiveness. The success of the procedure can be reduced if the stomach pouch is stretched and/or left larger than 15-30cc (1/2 to one ounce). Poor views of internal organs. The bypassed portion of the stomach, duodenum, and segments of the small intestine are difficult to see using x-ray or endoscopy. This only becomes a problem if the patient develops ulcers, bleeding, or malignancy. Gastric bypass does not cause cancer. Nutrient deficiencies. Almost a third of patients develop nutritional deficiencies because the duodenum is bypassed in this procedure. So, the body doesn't absorb iron, calcium and other nutrients efficiently after surgery. Fortunately, these deficiencies can usually be controlled with proper diet and vitamin supplements. Nutrient deficiencies can lead to: Iron deficiency anemia. Because the duodenum is bypassed in this procedure, the body doesn't absorb iron and calcium very well after surgery, which can lead to iron deficiency anemia. This is a particular concern for patients who experience chronic blood loss during menstruation or from bleeding hemorrhoids. Osteoporosis. Because the body doesn't absorb calcium properly after surgery, there is a greater risk of developing osteoporosis. Metabolic bone disease. Also caused by bypassing the duodenum, some patients experience bone pain, loss of height, humped back, and fractures of the ribs and hip bones. Chronic anemia. This is a type of anemia caused by a deficiency of vitamin B12, which can usually be managed with pills or injections.