It consists of the temporary placement of a balloon occupying the gastric lumen, generating a restriction of intake. It has not achieved comparable results with laparoscopic bariatric surgery (15).

Equivalent to vertical gastrectomy, it is indicated in patients who are not candidates for bariatric surgery according to their BMI or those who prefer not to undergo standard surgery. The stomach volume is reduced by 70%, using an endoscopic suture device of the greater curvature. The technique is effective as it achieves clinically significant weight loss. The rate of postoperative serious adverse events is low, around 2.2%. But since it is a recent technique, there have been no comparative studies with conservative treatment and very few studies comparing it with bariatric surgery (16, 17).

It is a flexible tube-shaped lining that extends from the duodenum to the proximal jejunum, preventing food from passing to the intestinal villi in the first part of the small intestine. It is indicated mainly in patients with grade 1 and 2 obesity and T2DM due to its effect on glycemic homeostasis (1).

All candidates for bariatric surgery can be indicated, but the ideal prototype would be young women, with a BMI less than 50 kg/m², who understand the technique and are predisposed to physical activity and changes in eating habits.

The approach is always laparoscopic using the “pars flaccid” technique that replaces the “perigastric” approach, but it has been proven that it produced a higher percentage of dilatations or slides (18, 19). It begins by sectioning the gastrophrenic ligament at the angle of this. The “pars flaccid” of the gastrohepatic ligament is then opened to reveal the base of the right diaphragmatic pillar. The fat is dissected from the gastroesophageal junction and a retrocardial angle is created towards the angle of His, where the band is inserted. The band closes and tunnels on the anterior face. The band is connected to a subcutaneous reservoir that allows the diameter to be readjusted through the injection of saline solution (1).

A 15-year follow-up study of adjustable gastric banding developed in 2013 (3,227 patients) showed no perioperative mortality for the primary placement or for any revisional procedures. There was a mean of 47.0% EWL (percentage of excess weight loss) (n = 714; 95% CI = 1.3) for all patients who were at or beyond 10-year follow-up. Revisional procedures were performed for proximal enlargement (26%), erosion (3.4%), and port and tubing problems (21%). The band was explanted in 5.6% (20). This study was completed in 2019 at a single center where 8,378 laparoscopic adjustable gastic band (LAGB) patients were followed for up to 20 years with an overall follow-up rate of 54%. No surgical deaths occurred. Weight loss at 20 years was 30.1 kg, 48.9%EWL and 22.2% total weight loss (%TWL). Reoperation rate was initially high but reduced markedly with improved band and surgical and aftercare techniques (21).

Its use has now decreased due to suboptimal weight loss in patients, associated mechanical complications, and the high rate of band reoperation, removal, or revision (22). The gastric band has been widely abandoned by surgeons in most countries but deserves its mention by patients who currently still have a gastric band and need management and possible complications.

The introduction of the laparoscopic vertical sleeve gastrectomy (LVSG) has seen a marked rise in usage, even overtaking Roux-en-Y Gastric Bypass (RYGB) (23, 24); in fact, it has become the most popular operation for the treatment of morbid obesity in the United States and worldwide due to its technical simplicity and palatability to patients (25, 26).

From a functional point of view, LVSG modulates the physiology by changes in gastric emptying. Various studies describe an increase in the rate of emptying after of it and seem to be linked to the starting distance of the section from the pylorus (27). LVSG also causes physical loss of principal producer of ghrelin, classically attributed to the fundus gastric (28). Being a purely restrictive procedure, the LVSG works to reduce the caloric intake of patients and decrease appetite through removal of ghrelin producing cells (25).

It is indicated in patients with morbid obesity (BMI greater than 40 kg/m² or BMI greater than 35 kg/m² associated with concurrent diseases). In patients with a BMI greater than 50 kg/m² it can be used as the first stage of a surgery performed in two phases.

It may be the technique of choice in patients who require long-term oral pharmacological treatments whose absorption could be altered in the intestinal diversions, in patients with chronic intestinal diseases, with concomitant gastric pathology, hepatomegaly or cirrhosis, metabolic syndrome or with extreme ages (older 65 years or adolescents) (1).

The long-term data for outcomes from LVSG is still being developed (25). Even though data were insufficient for a meta-analysis of the sleeve gastrectomy developed in 2019, it showed that it generated a weighted mean of 57% EWL from the two small studies that were included in the systematic review (21).

Through this procedure, long-term weight loss and an improvement in concurrent diseases are achieved: T2DM, arterial hypertension, dyslipidemia, obstructive sleep apnea–hypopnea syndrome and arthralgias. Mainly through two mechanisms, decrease in gastric volume and anorectic action by decreasing the concentration of ghrelin when sectioning the gastric fundus (29–31).

Prognostic factors for weight loss after vertical gastrectomy have been identified: a preoperative BMI >50 kg/m², the presence of comorbidities, age >50 years, and distance >5 cm from the pylorus negatively influence the results (32).

The surgical procedure begins by placing the patient in a semi-sitting position with the legs spread. The surgeon stands between the legs of the patient, with the first assistant on the right and if there is a second on the left. Although there may be variations, usually five trocars are placed. The optic trocar is placed in the midline, slightly displaced to the left. The second is located to the left and above the optic trocar, left paramedial, for the surgeon’s right hand. The third is the right paramedial, for the surgeon’s left hand. The fourth trocar in the right subcostal area for the Genzime-type atraumatic liver retractor or for the left-sided assistant and the fifth trocar, in the left upper quadrant for the helper on the right side (33–35).

Before starting the procedure, the liver retractor lifts the left liver lobe to expose the lesser omentum, gastric antrum, and pylorus. It is important to respect a distance of 4–6 cm from the antrum proximal to the pylorus, to respect the pyloric sphincter. The anterior face of the antrum is grasped and pulled upwards, thus raising the greater omentum and separating it from the transverse mesocolon. The horizontal greater curvature and the lower part of the vertical greater curvature are released, to continue releasing the upper part and the left pillar of the diaphragm. Once the posterior aspect is completely released, the gastric section can be continued. A 34-42 French gauge spark plug is placed up to the duodenum; thus, when cutting the laparoscopic stapler at its end, it contacts the spark plug. The section begins at the gastric antrum to the upper end of the stomach. To check the tightness of the staple, methylene blue is inserted through the nasogastric tube to tighten the gastric cuff. Finally, the gastrectomy piece is extracted into a bag (31).

Concerns with the LVSG in the long term revolve around development or worsening of gastroesophageal reflux disease (GERD) or weight regain. The evidence places the incidence de novo GERD between 0 and 34.9% (1, 25, 28). Another frequent surgical complication is gastric fistula, which is observed in 0.6–4.3% of cases. It occurs mainly in the gastroesophageal junction, the most feared being the one produced in the staple line. It is diagnosed especially in the first five postoperative days. In these cases, it is usually necessary to reoperate the patient (36). The risk of postoperative bleeding is less than 1%. Gastric stenosis is another complication, mainly at the level of the incisura angularis, but it is infrequent, occurring only in 0.7–4% of patients (37, 38). The main causes of mortality are lung embolism, cardiorespiratory failure, and complications of fistulas (39).

Weight loss and the benefits in comorbidities with this technique seem to be superior to the adjustable gastric band, and close to the results of malabsorptive techniques, but without presenting as many risks as these.

Gastric bypass, or gastrointestinal bypass, is a mixed technique. It is restrictive due to the small gastric pouch that reduces food intake, and malabsorptive due to the bypass of the pancreatic duodenum that carries partially digested food to the distal intestine, leading to a malabsorption of sugars and fats, improving glycemic balance (40–42).

The mechanisms of action include mechanical restriction of ingested calories due to the small gastric pouch, mild malabsorption due to the bypassing of a reasonable portion of the jejunum, and hormonal changes ensuing from the two latter, like reduction of the production of ghrelin from the excluded gastric fundus, early secretion of peptide YY(PYY) from the distal ileum and changes in the levels of various incretins such as GLP1 (43).

RYGB is the most frequent procedure to treat the severely obese in Europe (44–46) particularly in the presence of gastroesophageal reflux or T2DM (44, 46, 47).

It is the reference technique for the severely and morbidly obese patients, producing 72% weight loss after two years. Its efficacy, with a remission of T2DM in 84% at two years, has made it evolve as one of the possible treatments for this pathology (metabolic surgery). On the other hand, concurrent diseases and cardiovascular risk decrease, in relation to the improvement in inflammation markers, endothelial dysfunction and atherosclerosis after bariatric surgery (40–42).

It is indicated for use in patients with stable or increasing obesity for five years or more, after failure of conservative treatment, with a BMI greater than or equal to 40 kg/m² or greater than or equal to 35 kg/m² with comorbidities. It is especially indicated for use in obese diabetics with metabolic syndrome and cardiovascular risk. It is the key technique in patients with a tendency to peck due to the malabsorptive effect and also in patients with gastroesophageal reflux as a second choice in the face of the failure of restrictive interventions (48).

The operation begins by placing the patient in a semi-sitting position. The surgeon will stand between the legs of the patient, with the first assistant on the right and if there is a second assistant on his left. Before the operation, a nasogastric tube, antibiotic prophylaxis, and compression stockings are placed on the lower extremities to prevent thromboembolic risk. Surgery begins by insufflating the pneumoperitoneum into the abdominal cavity. The five trocars are then placed in the supraumbilical region. The first one below the xiphoid appendix, slightly displaced to the left where the optic will go. The second and third are the working trocars, one at the right pararectal level and the other at the left pararectal level.

First, the liver is rejected with the retractor in order to gain access to the supramesocolic region. To expose the duodenojejunal angle, the free edge of the greater omentum is divided to the greater curvature of the stomach, and the transverse mesocolon is elevated.

To perform the gastric pouch, the lesser curvature begins by dissecting the lesser curvature to move towards the lesser sac. The nasogastric tube is removed and the first horizontal stapling is performed. This is continued with the vertical section parallel to the lesser curvature up to the angle of His. The proximal jejunal loop ascends to the gastric pouch. An enterotomy of the jejunal loop and a gastrotomy are performed in the declining part of the gastric stapling. The posterior wall is anastomosed with a linear stapler and then the anterior surface is sutured with resorbable thread. The biliary loop is divided, transforming the loop into an omega into a Y loop. The next step is to measure the alimentary loop from the gastrojejunal anastomosis, which should not be more than 200 cm long. On both handles, the alimentary and the biliary ones, an enterotomy is performed on the antimesenteric border of each one and they are anastomosed laterally with a linear stapler. Finally, the Petersen space (between the meso of the ascended alimentary loop and the transverse mesocolon) is closed with running sutures to avoid internal hernias. There are schools in which the loop foot is made first and then the gastric reservoir and gastrojejunal anastomosis are made (48).

Some complications may appear:

To overcome the technical limits of laparoscopy and to potentially flatten the learning curve, the robotic system was introduced into bariatric surgery. The robotic approach might improve the outcome in revisional bariatric surgery. Its high cost is a major handicap, so its role in bariatric surgery is still unclear (46, 58).

One anastomosis gastric bypass has gained popularity in recent years. It is now the third most commonly performed bariatric surgery worldwide after sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) (44). Its advantages include short operative time, a single anastomosis, acceptable rates of short-term complications, and effective weight loss (59).

Given that the Y-shunt is currently the procedure of choice, the OAGBP presents less technical difficulty than the Y-shunt due to the need for a single anastomosis (omega shunt) between the gastric tube and the jejunal loop. It achieves weight loss and resolution of T2DM comparable to gastric bypass (60).

Although this technique is gaining popularity, surgeons are reluctant to perform it because the long-term results are not well defined and prospective data are not available. In addition, there is controversy regarding its safety because omega mounting exposes them to have a greater probability of bile reflux in the gastric bag, and ulcers. In the studies carried out, it has also been seen that the omega shunt has a higher risk of protein and lipid malabsorption compared to the Y shunt, producing cases of severe malnutrition (61, 62).

In a systematic review of 12,807 MGB-OAGBP procedures described that the overall mortality was 0.10% and the leak rate was 0.96%. The follow-up duration ranged from 6 months to 12 years. A marginal ulceration rate of 2.7% and an anemia rate of 7.0% were reported. Approximately 2.0% of patients reported postoperative gastro-oesophageal reflux and 0.71% developed malnutrition. Excess weight loss at 6, 12, 24, and 60 months was 60.68, 72.56, 78.2, and 76.6% respectively. T2DM and hypertension resolved in 83.7 and 66.94% respectively. It concluded that there is now sufficient evidence to include MGB-OAGB as a mainstream bariatric procedure (63).

Therefore, it is not part of the recommended reference techniques, although in cases of massive abdominal obesity with thick and short mesos that limit the performance of the Y-shunt, it could be indicated (48).

A common loop of 100–150 cm is made from the ileocecal valve and a posterior gastric section without gastrectomy, and gastrojejunal anastomosis.

It is indicated for use in patients with very high BMI, even above 60 kg/m², since it is the intervention with the greatest malabsorption, also in patients with T2DM and other comorbidities since it favors its resolution, and in those patients who do not want to change their eating habits, since the food restriction is decreasing in time, being able to eat normally three months after the intervention (1).

Gastroileal bypass is a modification of the biliopancreatic diversion technique. To avoid postoperative complications, it is performed without gastrectomy. It can be executed in two stages in patients with cardiac and respiratory risk. First, the gastroileal anastomosis is performed and secondly, the biliary intestine is divided by anastomosing it 100 cm from the ileocecal valve. The first stage of this intervention is what is currently called gastroileal bypass.

It is a simple, fast, safe and reproducible technique, obtaining excellent results. It is minimally restrictive, with great malabsorption. It can be used in patients with a BMI greater than 35 kg/m² or with T2DM and BMI between 30 and 35 kg/m² (64).

An alternative to the previous technique, a vertical gastrectomy is performed with preservation of the pylorus and the duodenum is divided. At 300 cm from the ileocecal valve, the mesentery is divided into the duodenal loop and the biliopancreatic loop. The duodenal loop ascends retrocolically through the mesenteric orifice and anastomoses with the gastric pouch (duodenoileal anastomosis). Subsequently, an anastomosis is made between the biliopancreatic loop and the common loop 100 cm from the ileocecal valve. It is the preferred choice in patients with a BMI greater than 50 kg/m² and with comorbidities, since it has been shown to have the best weight loss results and their resolution. Additionally, it has the benefit of being able to eat all kinds of food, improving the quality of the intake (1, 65).

It is an alternative to the duodenal switch. It consists of a single duodenoileal anastomosis together with a vertical gastrectomy. The duodenum is anastomosed directly to the omega loop of the ileum 200 cm from the ileocecal valve. The main benefit is a reduction in operative risk by performing only one anastomosis.

It is worth mentioning that the biliopancreatic diversion, the cost bypass, the duodenal switch and the SADI-S conceptually belong to the same type of interventions with some distinction.

SADI-S has been demonstrated to be a safe and reproducible technique and offers good weight loss results in the short term (66, 67). Results on diabetes are comparable to those obtained with the duodenal switch (68), and some studies have even found a better metabolic effect thanks to the longer common channel (69, 70).

There is no medical evidence to demonstrate the superiority of the duodenal switch over SADI-S, or about the long-term medical safety or efficacy of SADI-S (71). A study has recently been published reporting the 5 to 10-year outcome of a series of 164 patients consecutively submitted to primary SADI-S. There was no mortality. One patient had a gastric leak, and 2 patients had an anastomotic leak. A total of 25% of the patients were lost to follow-up at 10 years. Excess weight loss and total weight loss were 87 and 38% at 5 years and 80 and 34% at 10 years. A total of 12 patients were submitted to revisional surgery for hypoproteinemia. Preoperatively 41 diabetics were under insulin treatment; at 5 years, 7 remained with insulin and 12 at 10 years. Mean glycemia was 104 mg/dl at 5 years and 118 mg/dl at 10 years. Mean HbA1c was 5.51% at 5 years and 5.86% at 10 years. This allows concluding that in the long term, SADI-S seems to offer satisfactory weight loss and comorbidities resolution but there is insufficient data to comment on the long-term safety and efficacy of SADI-S (70). However, more studies should be done.