The AGB is a purely restrictive procedure. A soft silicone band is positioned around the upper part of the stomach, creating a small gastric pouch. The inner balloon is inflatable allowing for modifiable mechanical restriction of the pouch outlet or stoma, which minimizes the amount of food that can be consumed during a meal, as well as increases the time for emptying of the gastric pouch. Mechanical restriction is thought to be the main mechanism of satiety and weight loss. The AGB procedure gained popularity as an alternative to the GB with its superior safety profile and simpler technique. Once the most commonly performed weight loss procedure in the USA, it has seen a steady decline in recent years [22].

Current devices evolved from non-AGB placed via an open technique to AGB that are placed laparoscopically. These modifications were developed during a time when bariatric surgeons had become comfortable with the technique of open vertical banded gastroplasty (VBG), yet desired to offer treatments for morbid obesity utilizing a minimally invasive approach with the flexibility and advantage of an adjustable outlet. There are two FDA-approved devices in the USA. The REALIZE^® band (manufactured by Ethicon) is a high-volume, low-pressure device modeled after the Swedish adjustable gastric band (SAGB). The LAP-BAND™ (manufactured by Allergan, Santa Barbara, CA), in contrast, is a high-pressure, low-volume band, similar to that of the Kuzmak band, which was placed in an open fashion in 1984 [23]. Belachew is credited with describing the first laparoscopic placement of an AGB in 1993 [24].

The AGB procedure begins after initial trocar placement and retraction of the liver. The placement of the band was originally described via a perigastric approach, similar to that utilized in open placement of non-AGB, with an opening in the lesser curve of the stomach medial to the gastric vessels [23]. This has largely been replaced by the pars flaccida technique, developed to decrease the incidence of prolapse and pouch dilation seen with the perigastric technique. In the pars flaccida approach, the lesser sac is not entered, and instead a smaller footprint retroesophageal window is created by dissecting the peritoneum at the edge of the right crus. The phrenogastric ligament at the angle of His is also dissected. A blunt articulating dissector is then passed from the vicinity of the right crus to the dissected area of the angle of His, through which the tubing of the band can be pulled and the band buckled into place. A calibrating balloon can be used to size the gastric pouch at 10–20 mL. Although not utilized by all surgeons, three to four gastrogastric plication sutures can be placed to stabilize the gastric pouch anteriorly. Less weight loss and increased risk of prolapse have been associated with findings of unrepaired hiatal hernias after AGB. It is therefore felt to be important to look for the presence of hiatal hernias, frequently missed on preoperative imaging studies. Concomitant hiatal hernia repair when identified during AGB has been found to be safe and is associated with decreased subsequent band-related complications [25]. The band tubing is then externalized and connected to a subcutaneous access port, which is positioned and secured on the anterior rectus sheath. Port placement should also consider the ease of superficial palpation of the port, as well as avoiding the oblique muscles, which may promote more movement or flipping of the port. Some surgeons may choose to reinforce the access port placement with a small piece of fitted mesh to create additional natural adhesion formation for added security.

Patients are seen for interval visits for band adjustments usually beginning at 4–6 weeks after surgery. Incremental amounts of saline can be added or removed from the access port. Band adjustments are an integral part of maximizing the efficacy of the device and are generally performed in the office by palpating the access port and inserting a long Huber-type needle. Adjustments can also be performed with the aid of ultrasound or fluoroscopy when the port is difficult to identify. Fluoroscopy with contrast can also be useful to calibrate the outlet visually. Given variable stomach thicknesses and individual tolerance to restriction, there is no standard amount of fluid or number of adjustments appropriate for all patients. Most patients, however, will require anywhere from 5 to 7 adjustments per year in the first 1–2 years, with varying number of adjustments thereafter. Partial or complete deflation of the band can be performed for any negative symptoms resulting from over-restriction (nausea, vomiting, dysphagia, gastroesophageal reflux disease (GERD)). Fluoroscopy is the diagnostic study of choice to evaluate for changes in the position of the band, and evaluate for obstruction of flow, prolapse (anterior or posterior protrusion of the stomach), or slip. Chronic over-restriction and vomiting can result in erosion of the gastric band, where a part of the band or its entirety becomes internalized within the lumen of the stomach. The diagnostic study of choice for evaluation of a suspected erosion is upper endoscopy. Port complications , such as infection, flipping (limiting the ability to access the port), local pain, and separation of the port from the band tubing (resulting in band leakage and inadequate restriction), are a rare cause of major morbidity, and can generally be repaired with a brief outpatient procedure; but they occur frequently, as reported in a recent systematic review with 15-year follow-up, by O’Brien et al., at 21 % [26].

The primary benefit of the AGB over other bariatric procedures is its safety profile, as well as the ability to restore original anatomy if necessary. Given that the stomach is not divided or stapled, it is not surprising that the AGB has the lowest mortality rate of any bariatric procedure, ranging from 0 to <0.1 % in most published series [26]. There is also no alteration in the pathway of nutrient flow; therefore, it has the lowest risk of micronutrient deficiency and medication malabsorption. Several meta-analyses and systematic reviews with long-term follow-up show durable weight loss of over 40–50 % excess weight loss (%EWL) beyond 10 years [26]. The limitations o f the AGB are related to higher variability of weight loss between individuals as well as the high rate of reoperations ranging in published studies from 8 to 60 % at 10 or more years of follow-up [27].

The sleeve gastrectomy (SG) is both the newest and now most commonly performed bariatric procedure in the USA, surpassing rates of GB in 2013 [28]. The SG is technically less challenging than the GB and biliopancreatic diversion with duodenal switch (DS), as no anastomosis is created, but, unlike the AGB, results in changes in gut hormones and gastric emptying, among others. The SG involves removal of the majority of the greater curvature of the stomach resulting in a significantly narrowed and tubularized stomach. The reduced capacity restricts the amount of food consumed and the removal of the fundus reduces both fasting and postprandial levels of ghrelin (a gut hormone involved in stimulating appetite) [29]. The SG provides an alternative option for patients where the GB may be contraindicated, such as patients with inflammatory bowel disease (where manipulation of the small intestine is generally not advised), and who require chronic steroid or NSAID use (promotes marginal ulceration). The SG may also be preferable for those patients who have a history of extensive prior abdominal surgery, large concomitant ventral hernias, chronic renal disease, and early cirrhosis.

Creation of a sleeve gastrectomy is the first part or stage of the DS. The DS procedure is a technically complex procedure with two separate anastomoses and has been associated with a high morbidity and mortality rate when performed in super-super obese patients (BMI >65 kg/m²) [30]. In an effort to help reduce the operative morbidity and mortality, the DS was sometimes aborted after the SG component or offered as a planned two-stage procedure, in which only the sleeve gastrectomy was performed. Patients would then be followed for interval weight loss and would be brought back for the malabsorptive portion (second stage) or completion DS once there had been improvement in visceral adiposity, generally 6–12 months later. The utilization of the SG as a staged procedure for DS was first performed in 2000 by Gagner, who also described the utilization of the SG as a staged procedure with completion GB for super obese patients [31]. Over time, it was recognized that some patients were able to achieve and maintain adequate weight loss and did not need to undergo the second stage to a DS or GB. In 2007, there were several studies published looking at the merits of standardization and utilization of the sleeve gastrectomy as a new stand-alone primary treatment for morbid obesity [32, 33]. In 2009, the ASMBS recognized the SG as a standard primary treatment for morbid obesity as well as an option for staging, based on reasonable mid- to long-term data on the safety, efficacy, and durability of outcomes [34]. Ongoing efforts for standardization of SG (technique, management) have led to several international consensus summits and international expert panels, beginning in 2007, which have helped provide collective input on many clinical aspects of the SG, in the form of best practice guidelines and statements [35, 36].

The modern SG begins after trocar placement (generally 5–6), retraction of the liver, and identification of the pylorus. A distance of 2–4 cm on the antrum is marked to begin dissection of the greater curve vessels and ultimate division of the stomach. A bougie or calibrating tube is used to help standardize the size of the gastric conduit, as well as to prevent overnarrowing of the sleeve, and is considered a mandatory component of the modern SG with reported sizes ranging from 32 to 46 Fr. Sequential firings of the linear stapler are continued toward the angle of His. It is important to identify the left crus to ensure adequate dissection as it is also generally recommended to repair any concomitant hiatal hernias to prevent worsening of GERD [34, 35].

Early complications include bleeding, stricture, and leak. Late complications include chronic fistula, stricture, pouch dilatation, unrecognized hiatal hernias, and worsening of GERD. Leaks have been identified and described more than 30 days after SG. Most late leaks occur secondary to findings of distal stricture or kinking of the sleeve. The most common location for leaks after SG is the upper portion of the sleeve near the angle of His. Vascular changes as well as pressure changes from a tubularized, less distensible stomach against a closed pylorus are thought to be contributing factors in the etiology of leaks after SG [37, 38]. A recent meta-analysis found a slightly higher incidence of leak after SG, ranging from 2.3 % compared to 1.9 % after GB. The mortality, however, is comparable or less than that of GB, at 0.2 % for SG vs. 0.4 % for GB [39]. This is comparable to findings in a systematic review by the Clinical Issues Committee of the ASMBS, which reported a leak rate of 2.2 % and mortality rate of 0.19 % for SG. Percent EWL with at least 3-year follow-up was reported at 55 % [40].

Like GB and DS, weight-independent improvement of glycemic control and resolution of diabetes have been shown after SG. As with GB and DS, the mechanisms of diabetes resolution and weight loss are not completely understood. Although the SG does not involve alteration in the pathway of nutrient flow, findings of both increased gastric emptying and intestinal transit have been shown in animal models [41]. It is thought that this may be a mechanism to help explain findings of increased incretin production of hormones such as peptide YY (PYY) and glucagon-like-peptide-1 (GLP-1), not observed after AGB, which are both promoters of an anorectic state as well as implicated in glucose homeostasis [42]. Both SG and GB have been shown in a recent randomized controlled trial (RCT) reported by Schauer et al. to have significantly greater glycemic control for obese diabetics compared to best medical management with mid-term results at 3 years [43]. Ongoing research is required to fully understand the durability of these effects.

Once the most commonly performed bariatric procedure in the USA, the GB has been positioned as the “gold standard” bariatric procedure since the early 1990s, but was surpassed in volume of cases per year by the SG in 2013 [28]. The GB procedure was first described in 1967 by Mason and Ito, and involved a horizontally based gastric pouch and “loop” gastroenterostomy [44]. Complications of bile alkaline reflux and marginal ulcers led to many modifications of the procedure over the subsequent years, with changes in both the size and configuration of the gastric pouch (lesser curve or vertically based) as well as replacing the “loop” anastomosis with a Roux-type anastomosis. The procedure was performed in an open fashion though an upper midline incision. Not surprisingly, abdominal wound infections and incisional hernias were fairly common complications seen after open gastric bypass surgery [45]. Advances in laparoscopic technology and minimally invasive surgery techniques as well as improved perioperative outcomes from fewer wound and cardiopulmonary complications, reduced length of stay, and shorter recovery witnessed for cholecystectomy, hernia, and anti-reflux procedures in the early 1990s helped provide the rationale for utilizing such techniques in bariatric surgery. In 1994, Wittgrove and Clark detailed the first laparoscopic gastric bypass procedure. Using six trocars, they created a small 15–30 cm³ proximal pouch, a 21 mm circular stapled end-to-end (EEA) gastrojejunal anastomosis, and a 75 cm retrogastric, retrocolic Roux limb [46].

In 2000, Wittgrove and Clark published the results of 500 consecutive laparoscopic GB procedures with up to 60-month follow-up to show 0 % mortality, leak rate of 2.2 %, overall complication rate of less than 10 %, and mean excess body weight loss of 73 % at 54 months [47]. The modern GB is performed using 4–6 abdominal trocars and consists of a small proximal 15–30 cm³ gastric pouch, with a Roux limb (alimentary limb) length of 75–150 cm to prevent bile reflux, which is then anastomosed to the biliopancreatic limb. Since 1994, there have been many different laparoscopic GB techniques described, with minor variations in how the gastrojejunal anastomosis is created (hand–sewn vs. linear vs. circular stapled) and positioned (retrogastric, retrocolic, antegastric, antecolic, or combination). The use of robotic assistance has also been described [48]. These different GB techniques are generally felt to be comparable in safety, efficacy, and outcomes with surgeon preference being the predominant factor in determining which approach is chosen [49–51].

The primary mechanisms of weight loss include caloric restriction, and reduction of ghrelin. Ghrelin is a peptide hormone secreted primarily in the stomach and foregut that stimulates the early phase of meal consumption and is significantly reduced after GB [52]. Increased incretin production of hormones such as PYY and GLP-1 seen after GB may also contribute to an anorectic state and are also thought to contribute to the weight-independent metabolic changes resulting in improved glycemic control, reduced insulin resistance, and euglycemia which can be seen within days of GB, long before significant weight loss has occurred [53, 54]. Although the metabolic changes relative to improved glycemic control after GB were first published by Pories in 1995, the mechanisms of diabetes improvement after GB remain an area of ongoing research [54, 55]. Additional mechanisms of weight loss are related to the creation of a gastrojejunostomy and loss of the pylorus which can allow symptoms of dumping syndrome to occur such as nausea, abdominal discomfort, diarrhea, and diaphoresis after ingestion of foods high in sugar or fat. The negative response to sugar-rich foods after GB has long been thought as a potential benefit to inhibit the patient from consuming carbohydrates over purely restrictive procedures [56].

The GB procedure has an excellent safety profile. Recent published data from the American College of Surgeons National Surgical Quality Improvement Program database shows 30-day mortality rates of 0.15 % [57]. This is similar to findings in a large systematic review and meta-analysis published by Buchwald in 2007, with mortality rates of 0.16 % [58]. Early complications include leak, deep venous thrombosis/pulmonary embolus, bleeding, and strictures with major morbidity of 5.8 % [58]. Late complications include internal hernias, marginal ulcers, gastro-gastric fistulas, biliary tract disease, as well as nutritional deficiencies [59].

There is a variable range of long-term weight loss outcomes after GB . A recent systematic review of RCTs and observational studies that included at least 50 patients, with 2 or more years of follow-up and at least 80 % of patients at follow-up, reported the sample size-weighted mean percentage of EWL for gastric bypass at 65.7 %. This study also found sample size-weighted remission rates of diabetes, hypertension, and hyperlipidemia resolution rates at 66.7 % (n = 428 patients), 38.2 % (n = 808 patients), and 60.4 % (n = 477 patients), respectively [60]. It is understood that some weight regain can occur, as well as the development of new-onset diabetes or recurrence of diabetes. Adams et al. showed a reduction of diabetes remission rates after GB from 75 to 62 % at 2–6 years after surgery [61]. Adams and others have documented a reduction in overall mortality after GB [61, 62].

The DS is a modern variant of the biliopancreatic diversion (BPD), a malabsorptive procedure developed by Scopinaro in 1979 [63]. The BPD, itself, was a modification of an older now abandoned procedure, the jejunoileal bypass (JIB) from the 1950s, which provided excellent weight loss from malabsorption of nutrients, but had a very long blind intestinal limb-promoting stasis, bacterial overgrowth, and even liver failure [64]. Scopinaro omitted the stasis in the intestinal bypass by separating the intestine into a long alimentary and biliopancreatic limb. A subtotal gastrectomy was performed, which provided additional restriction of food and removed the antrum to reduce the risk of peptic ulcer disease. Malabsorption resulted from a short common channel (where the biliopancreatic limb is connected to the alimentary limb) positioned at a variable distance of 50–125 cm from the ileocecal valve. This procedure provided excellent weight loss but had a high rate of postgastrectomy complications from removal of the pylorus such as dumping, and marginal ulcer. The BPD was modified to preserve the pylorus, switching from a subtotal gastrectomy to a lesser curve-based tubular sleeve gastrectomy, with transection of the duodenum and addition of a duodenoileostomy, described by both Hess and Hess and Marceau in 1998 [65, 66]. These modifications resulted in significant reduction of postgastrectomy symptoms and incidence of marginal ulcer . In long-term studies reported by Marceau et al. and Hess et al., with 15-year and 10-year follow-up, marginal ulceration was reduced to 0.1 % and 0.3 %, respectively [67, 68].

The DS is the most technically difficult bariatric procedure, with operative times routinely 60–120 min longer than other bariatric procedures, which has traditionally been performed as an open procedure and was the last of the contemporary bariatric procedures to be adapted to a laparoscopic approach [30]. The modern DS begins with trocar placement of six or more abdominal trocars and creation of a sleeve gastrectomy, beginning 4–6 cm from the pylorus, generally larger in capacity than the standard SG (performed as a primary procedure), with bougie sizes of 36–60 Fr described. Duodenal transection ensues, with creation of a retroduodenal tunnel at the level of the gastroduodenal artery. Duodenal transection is generally considered the most technically challenging part of the DS procedure given the risks of bleeding, pancreatic injury, and ischemia of the duodenum. The common, alimentary (Roux limb), and biliopancreatic limbs are then created by first identifying the ileocecal valve and measuring proximally a distance of 75–100 cm which marks the position of the common channel. This location is usually marked with a stitch. The bowel is run proximally an additional distance of 150–175 cm and transected. The alimentary limb (portion of the transected bowel that is in continuity with the colon) is then brought up and connected to the duodenum through an opening in the omentum or mesocolon. Hand-sewn, linear, and circular stapled duodenoileostomy techniques have been described. The distal end of the transected jejunum or ileum (depending on where the intestine is transected) that is in continuity with the ligament of Treitz is the biliopancreatic limb, which is then anastomosed to the ileum at the common channel where a stitch marks a total distance of 75–100 cm. Enteroenterostomy defects are generally closed to prevent internal hernias. The closure of the Petersen defect (cut edge of Roux limb mesentery) is controversial with some surgeons advocating closure and others who feel that closure risks leaving the potential for a small defect with greater risk of bowel strangulation [69, 70]. The ileoileostomy or jejunoileostomy has been described using hand-sewn, partial, or total linear stapled techniques. As with GB, minor differences in the technical approach to DS are generally felt to have similar outcomes with the chosen technique based primarily on surgeon preference. A decision to stage the DS remains an option intraoperatively and should be determined before committing to the malabsorptive components of the procedure. Reasons for staging include anatomic issues affecting feasibility to complete the malabsorptive component laparoscopically as well as physiologic concerns related to intraoperative stability or intolerance to pneumoperitoneum.