Any major<unk>  involves the potential for complications—adverse events that increase risk, hospital stay, and mortality. Some complications are common to all abdominal operations, while some are specific to bariatric<unk> . Mortality and complication rates The overall rate of complications during the 30 days following<unk>  ranges from 7% for laparoscopic procedures to 14.5% for operations through open incisions. One study on mortality revealed a 0% mortality rate out of 401 laparoscopic cases, and 0.6% out of 955 open procedures. Similar mortality rates—30-day mortality of 0.11%, and 90-day mortality of 0.3%—have been recorded in the U.S. Centers of Excellence program, the results being from 33,117 operations at 106 centers. Mortality and complications are affected by pre-existing risk factors such as degree of obesity, heart disease, obstructive sleep apnea, diabetes mellitus, and history of prior pulmonary embolism. It is also affected by the experience of the operating surgeon: the learning curve for laparoscopic bariatric<unk>  is estimated to be about 100 cases. Supervision and experience are important when selecting a surgeon, as the way a surgeon becomes experienced in dealing with problems is by encountering and solving them. Complications of abdominal<unk>  Infection Infection of the incisions or of the inside of the abdomen (peritonitis, abscess) may occur due to the release of bacteria from the bowel during the operation. Nosocomial infections, such as pneumonia, bladder or kidney infections, and sepsis (blood-borne infection) are also possible. Effective short-term use of antibiotics, diligent respiratory therapy, and encouragement of activity within a few hours after<unk>  can reduce the risks of infections. Venous thromboembolism Any injury, such as a surgical operation, causes the body to increase the coagulation of the blood. Simultaneously, activity may be reduced. There is an increased probability of formation of clots in the veins of the legs, or sometimes the pelvis, particularly in the morbidly obese patient. A clot that breaks free and floats to the lungs is called a pulmonary embolus, a very dangerous occurrence. Blood thinners are commonly administered before<unk>  to reduce the probability of this type of complication. Hemorrhage Many blood vessels must be cut in order to divide the stomach and to move the bowel. Any of these may later begin bleeding, either into the abdomen (intra-abdominal hemorrhage) or into the bowel itself (gastrointestinal hemorrhage). Transfusions may be needed, and re-operation is sometimes necessary. The use of blood thinners to prevent venous thromboembolic disease may actually increase the risk of hemorrhage slightly. Hernia A hernia is an abnormal opening, either within the abdomen or through the abdominal wall muscles. An internal hernia may result from<unk>  and re-arrangement of the bowel and is a cause of bowel obstruction. Antecolic antegastric Roux-en-Y<unk>  has been estimated to result in internal hernia in 0.2% of cases, mainly through Petersen's defect. An incisional hernia occurs when a surgical incision does not heal well; the muscles of the abdomen separate and allow protrusion of a sac-like membrane, which may contain bowel or other abdominal contents, and which can be painful and unsightly. The risk of abdominal-wall hernia is markedly decreased in laparoscopic<unk> . Bowel obstruction Abdominal<unk>  always results in some scarring of the bowel, called adhesions. A hernia, either internal or through the abdominal wall, may also result. When the bowel becomes trapped by adhesions or a hernia, it may become kinked and obstructed, sometimes many years after the original procedure. An operation is usually necessary to correct this problem. Complications of<unk><unk>  Anastomotic leakage An anastomosis is a surgical connection between the stomach and bowel, or between two parts of the bowel. The surgeon attempts to create a water-tight connection by connecting the two organs with either staples or sutures, either of which actually makes a hole in the bowel wall. The surgeon will rely on the body's natural healing abilities and its ability to create a seal, like a self-sealing tire, to succeed with the<unk> . If that seal fails to form for any reason, fluid from within the gastrointestinal tract can leak into the sterile abdominal cavity and give rise to infection and abscess formation. Leakage of an anastomosis can occur in about 2% of Roux-en-Y<unk><unk>  and less than 1% in mini<unk><unk> . Leaks usually occur at the stomach-intestine connection (gastro-jejunostomy). Anastomotic stricture As the anastomosis heals, it forms scar tissue, which naturally tends to shrink ("contract") over time, making the opening smaller. This is called a "stricture". Usually, the passage of food through an anastomosis will keep it stretched open, but if the inflammation and healing process outpaces the stretching process, scarring may make the opening so small that even liquids can no longer pass through it. The solution is a procedure called gastro endoscopy, and stretching of the connection by inflating a balloon inside it. Sometimes this manipulation may have to be performed more than once to achieve lasting correction. Anastomotic ulcer Ulceration of the anastomosis occurs in 1–16% of patients. Possible causes of such ulcers are: * Restricted blood supply to the anastomosis (compared to the blood supply available to the original stomach) * Anastomosis tension *<unk>  acid * The bacteria Helicobacter pylori * Smoking * Use of non-steroidal anti-inflammatory drugs This condition can be treated with: * Proton pump inhibitors, e.g. esomeprazole * A cytoprotectant and acid buffering agent, e.g. sucralfate * Temporary restriction of the consumption of solid foods Dumping syndrome Normally, the pyloric valve at the lower end of the stomach regulates the release of food into the bowel. When the<unk><unk>  patient eats a sugary food, the sugar passes rapidly into the intestine, where it gives rise to a physiological reaction called dumping syndrome. The body will flood the intestines with<unk>  content in an attempt to dilute the sugars. An affected person may feel their heart beating rapidly and forcefully, break into a cold sweat, get a feeling of butterflies in the stomach, and may have an anxiety attack. The person usually has to lie down and could be very uncomfortable for 30–45 minutes. Diarrhea may then follow. Nutritional deficiencies Nutritional deficiencies are common after<unk> , and are often not recognized. They include: * Secondary hyperparathyroidism due to inadequate absorption of calcium may occur for GBP patients. Calcium is primarily absorbed in the duodenum, which is<unk> ed by the<unk> . Most patients can achieve adequate calcium absorption by supplementation with vitamin D and calcium citrate (carbonate may not be absorbed—it requires an acidic stomach, which is<unk> ed). * Iron frequently is seriously deficient, particularly in menstruating females, and must be supplemented. Again, it is normally absorbed in the duodenum. Ferrous sulfate can cause considerable GI distress in normal doses; alternatives include ferrous fumarate, or a chelated form of iron. Occasionally, a female patient develops severe anemia, even with supplements, and must be treated with parenteral iron. The signs of iron deficiency include: brittle nails, an inflamed tongue, constipation, depression, headaches, fatigue, and mouth lesions. * Signs and symptoms of zinc deficiency may also occur such as: acne, eczema, white spots on the nails, hair loss, depression, amnesia, and lethargy. * Deficiency of thiamine (also known as vitamin B1) brings the risk of permanent neurological damage (i.e. Wernicke's encephalopathy or polyneuropathy). Signs of thiamin deficiency are heart failure, memory loss, numbness of the hands, constipation, and loss of appetite. * Vitamin B12 requires intrinsic factor from the<unk>  mucosa to be absorbed. In patients with a small<unk>  pouch, it may not be absorbed, even if supplemented orally, and deficiencies can result in pernicious anemia and neuropathies. Vitamin B12 deficiency is quite common after<unk>  with reported rates of 30% in some clinical trials. Sublingual B12 (cyanocobalamin) appears to be adequately absorbed. In cases where sublingual B12 does not provide sufficient amounts, injections may be needed. * Protein malnutrition is a real risk. Some patients suffer troublesome vomiting after<unk> , until their GI tract adjusts to the changes, and cannot eat adequate amounts even with 6 meals a day. Many patients require protein supplementation during the early phases of rapid weight loss to prevent excessive loss of muscle mass. Hair loss is also a risk of protein malnutrition. * Vitamin A deficiencies generally occur as a result of fat-soluble vitamins deficiencies. This often comes after intestinal<unk>  procedures such as jejunoileal<unk>  (no longer performed) or biliopancreatic diversion/duodenal switch procedures. In these procedures, fat absorption is markedly impaired. There is also the possibility of a vitamin A deficiency with use of the weight-loss medication orlistat (marketed as Xenical and Alli). * Folate deficiency is also a common occurrence in<unk>  patients. Nutritional effects After<unk> , patients feel fullness after ingesting only a small volume of food, followed soon thereafter by a sense of satiety and loss of appetite. Total food intake is markedly reduced. Due to the reduced size of the newly created stomach pouch, and reduced food intake, adequate nutrition demands that the patient follow the surgeon's instructions for food consumption, including
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