as a result of deep vein thrombosis, in which blood clots form in the deep veins of the extremities, usually the legs. if not treated, the clot can travel to the heart and then to the lung. this adverse effect is simply prevented by heparin and lmwh, which are both blood thinning medications. dumping syndrome dumping syndrome is a condition characterized by quick emptying of the stomach and frequent bowel movements. it is more common following rygb than sg, and can typically be treated through dietary modification. metabolic bone disease metabolic bone disease manifesting as osteopenia and secondary hyperparathyroidism have been reported after roux-en-y gastric bypass surgery due to reduced calcium absorption. the highest concentration of calcium transporters is in the duodenum. since the ingested food will not pass through the duodenum after a bypass procedure, calcium levels in the blood may decrease, causing secondary hyperparathyroidism, increase in bone turnover, and a decrease in bone mass. increased risk of fracture has also been linked to bariatric surgery. cholelithiasis (gallstones) rapid weight loss after obesity surgery can contribute to the development of gallstones by increasing the lithogenicity of bile. estimates for prevalence of symptomatic cholecystitis after roux-en-y gastric bypass range from 3-13%. cholelithiasis can be managed with a removal of the gallbladder (cholecystectomy). renal effects adverse effects on the kidneys have been studied. hyperoxaluria that can potentially lead to oxalate nephropathy and irreversible renal failure is the most significant abnormality seen on urine chemistry studies. rhabdomyolysis leading to acute kidney injury, and impaired renal handling of acid and base has been reported after bypass surgery. additionally, nephrolithiasis (kidney stones) are common after roux-en-y gastric bypass, with estimates of prevalence ranging from 7-11%. nutritional deficiencies deficiencies of micronutrients like iron, vitamin b12, fat soluble vitamins, thiamine, and folate are especially common after malabsorptive bariatric procedures. seizures due to hyperinsulinemic hypoglycemia have been reported. inappropriate insulin secretion secondary to islet cell hyperplasia, called pancreatic nesidioblastosis, might explain this syndrome. mental health though many benefits to mental health are described above, there are several potential adverse effects that should be discussed. alcohol problems have been reported to be more common in patients who have undergone gastric bypass surgery. of note, patients who receive an rygb may reach a higher peak alcohol concentration more quickly, due to changes in their metabolism. in addition, self-harm behaviors and suicide appear to be increased in people with mental health issues in the five years after bariatric surgery had been done. types bariatric procedures can be grouped in three main categories: blocking (reduce the absorption of nutrients), restricting (decrease the size of the gut and therefore the amount of food that can pass through), and mixed which are understood to work by altering gut hormone levels responsible for hunger and satiety. however, this distinction might be less clear-cut than it may seem. for instance, while sleeve gastrectomy (discussed below) was initially thought to work simply by reducing the size of the stomach, research has begun to elucidate changes in gut hormone signaling as well. the two most frequently performed procedures are sleeve gastrectomy and roux-en-y gastric bypass (also galled gastric bypass), with sleeve gastrectomy accounting for more than half of all procedures since 2014. most common diagram of sleeve gastrectomy sleeve gastrectomy main article: sleeve gastrectomy sleeve gastrectomy, or gastric sleeve, is a surgical weight-loss procedure in which the stomach is reduced to about 15% of its original size, by the surgical removal of a large portion of the stomach, following the major curve. the open edges are then attached together (typically with surgical staples, sutures, or both) to leave the stomach shaped more like a tube, or a sleeve, with a banana shape. while this procedure was initially thought to work only by reducing the size of the stomach, recent research has also shown that there are changes in gut signaling hormones. the procedure is performed laparoscopically and is not reversible. it has been found to produce a weight loss comparable to that of roux-en-y gastric bypass. while it is not as effective at treating gerd or type 2 diabetes as rygb, it has less risk of side effects like ulcers or intestinal strictures (narrowing of the gut). roux-en-y gastric bypass surgery (rygb) roux-en-y gastric bypass.main article: gastric bypass surgery the roux-en-y gastric bypass is designed to alter the gut hormones that control hunger and satiety. while the complete hormonal mechanisms are still being understood, it is now widely accepted that this is a hormonal procedure in addition to restriction and malabsorption properties. gastric bypass is a permanent procedure that helps patients reset hunger and satiety by altering how the stomach and small intestine handle consumed foods. after the surgery, the stomach will be smaller and there will be an increase in baseline satiety hormones, to help the patient will feel full with less food. the gastric bypass had been the most commonly performed operation for weight loss in the united states, and approximately 140,000 gastric bypass procedures were performed in 2005. its market share has decreased, and since 2013, sleeve gastrectomy has overtaken rygb as the most common bariatric procedure. a factor in the success of any bariatric surgery is strict post-surgical adherence to a healthy pattern of eating. one common side effect of bariatric surgery that is commonly reported with rygb is dumping syndrome, in which food moves too quickly from the stomach to the small intestine. this can usually be treated through dietary changes. biliopancreatic diversion with duodenal switch (bpd/ds) biliopancreatic diversion.main article: biliopancreatic diversion with duodenal switch a slightly less common bariatric procedure, accounting for less than 1% of all bariatric procedures in 2016. the part of the stomach along its greater curve is resected and the remaining stomach is "tubulized" with a residual volume of about 150 ml. this volume reduction provides the food intake restriction component of this operation. this type of gastric resection is anatomically and functionally irreversible. the stomach is then disconnected from the duodenum and connected to the distal part of the small intestine. the duodenum and the upper part of the small intestine are reattached to the rest at about 75–100 cm from the colon.. like the roux en y bypass, it is now understood that its results are largely due to a significant alteration in gut hormones that control hunger and satiety, in addition to its restriction and malabsorption properties. the addition of the sleeve gastrectomy, causes further gut hormone set- point alterations by reducing levels of the hunger hormone, ghrelin. compared to the sleeve gastrectomy and rou-en-y gastric bypass, bpd/ds produces the best results in terms of durable weight loss and resolution of type 2 diabetes. vertical banded gastroplasty main article: vertical banded gastroplasty surgery in the vertical banded gastroplasty, also called the mason procedure or stomach stapling, a part of the stomach is permanently stapled to create a smaller pre-stomach pouch, which serves as the new stomach. stomach folding basically, the procedure can best be understood as a version of the more popular gastric sleeve or gastrectomy surgery where a sleeve is created by suturing rather than removing stomach tissue thus preserving its natural nutrient absorption capabilities. gastric plication significantly reduces the volume of the patient's stomach, so smaller amounts of food provide a feeling of satiety. the procedure is producing some significant results that were published in a recent study in bariatric times and are based on post-operative outcomes for 66 patients (44 female) who had the gastric sleeve plication procedure between january 2007 and march 2010. mean patient age was 34, with a mean bmi of 35. follow-up visits for the assessment of safety and weight loss were scheduled at regular intervals in the postoperative period. no major complications were reported among the 66 patients. weight loss outcomes are comparable to gastric bypass. the study describes gastric sleeve plication (also referred to as gastric imbrication or laparoscopic greater curvature plication) as a restrictive technique that eliminates the complications associated with adjustable gastric banding and vertical sleeve gastrectomy—it does this by creating restriction without the use of implants and without gastric resection (cutting) and staples. adjustable gastric band main article: adjustable gastric band the restriction of the stomach also can be created using a silicone band, which can be adjusted by addition or removal of saline through a port placed just under the skin. this operation can be performed laparoscopically, and is commonly referred to as a "lap band". weight loss is predominantly due to the restriction of nutrient intake that is created by the small gastric pouch and the narrow outlet. it is considered somewhat of a safe surgical procedure, with a mortality rate of 0.05%. intragastric balloon main article: intragastric balloon intragastric balloon involves placing a deflated balloon into the stomach, and then filling it to decrease the amount of gastric space. the balloon can be left in the stomach for a maximum of 6 months and results in an average weight loss of 5–9 bmi over half a year. the intragastric balloon is approved in australia, canada, mexico, india, united states (received fda approval in 2015) and several european and south american countries. the intragastric balloon may be used prior to another bariatric surgery in order to assist the patient to reach a weight which is suitable for surgery, further it can also be used on several occasions if necessary. there are three cost categories for the intragastric balloon: pre-operative (e.g. professional fees, lab work and testing), the procedure itself (e.g. surgeon, surgical assistant, anesthesia and hospital fees) and post-operative (e.g. follow-up physician office visits, vitamins and supplements). quoted costs for the intragastric balloon are surgeon-specific and vary by region. average quoted costs by region are as follows (provided in united states dollars for comparison): australia: us$4,178; canada: us$8,250; mexico: us$5,800; united kingdom: us$6,195; united states: us$8,150. endoluminal sleeve this is a flexible tube inserted, through the mouth and stomach, into the upper small intestine. the purpose is to block absorption of certain foods/calories. it does not involve actual cutting and so is designed to lower risks from infection etc. however the results were not conclusive and the device had issues with migration and slipping. a study recently done in the netherlands found a decrease of 5.5 bmi points in 3 months with an endoluminal sleeve. implantable gastric stimulation this procedure where a device similar to a heart pacemaker that is implanted by a surgeon, with the electrical leads stimulating the external surface of the stomach, is being studied in the usa. electrical stimulation is thought to modify the activity of the enteric nervous system of the stomach, which is interpreted by the brain to give a sense of satiety, or fullness. early evidence suggests that it is less effective than other forms of bariatric surgery. biliopancreatic diversion diagram of a biliopancreatic diversion.this operation is termed biliopancreatic diversion (bpd) or the scopinaro procedure. the original form of this procedure is now rarely performed and has been replaced with a modification known as biliopancreatic diversion with duodenal switch (bpd/ds), or simply duodenal switch (ds). part of the stomach is resected, creating a smaller stomach (however the patient can eat a free diet as there is no restrictive component). the distal part of the small intestine is then connected to the pouch, bypassing the duodenum and jejunum. in around 2% of patients there is severe malabsorption and nutritional deficiency that requires restoration of the normal absorption. the malabsorptive effect of bpd is so potent that, as in most restrictive procedures, those who undergo the procedure must take vitamin and dietary minerals above and beyond that of the normal population. without these supplements, there is risk of serious deficiency diseases such as anemia and osteoporosis. because gallstones are a common complication of the rapid weight loss following any type of bariatric surgery, some surgeons remove the gallbladder as a preventive measure during bpd. others prefer to prescribe medications to reduce the risk of post-operative gallstones. far fewer surgeons perform bpd compared to other weight loss surgeries, in part because of the need for long-term nutritional follow-up and monitoring of bpd patients. jejunoileal bypass main article: jejunoileal bypass this procedure is no longer performed. it was a surgical weight-loss procedure performed for the relief of morbid obesity from the 1950s through the 1970s