# Stomach reduction surgery

Stomach reduction surgery, also known as bariatric surgery, is a medical procedure aimed at facilitating weight loss by reducing the size of the stomach, thereby limiting food intake and promoting satiety with smaller portions. It is frequently used for cases where traditional weight loss approaches, consisting of diet and physical activity, have proven insufficient, or when obesity already significantly affects well-being and general health.
The weight-loss procedure involves reducing food intake. Some individuals might suppress bodily functions to reduce the absorption of carbohydrates, fats, calories, and proteins. The outcome is a significant reduction in BMI. The efficacy of stomach reduction surgery varies depending on the specific type of procedure. There are two primary divisions of surgery, specifically gastric sleeve surgery and gastric bypass surgery.

## History

Stomach reduction surgery has a historical record back to the 20th century, notably with the jejuno-ileal bypass developed by Kremen in 1954. This surgery marked the inception of metabolic surgery but was concerned by severe complications. Gastric bypass surgery, introduced by Dr. Mason in 1966, became a gold standard procedure with its "Roux-en-Y"(RYGBP) configuration, significantly reducing the adverse effects seen in earlier methods.
Sleeve gastrectomy (SG), is one of the most popular stomach reduction surgeries and was earliest performed in 1990 as a first-stage operation of duodenal switch (DS) surgery. Patients who go through SG typically experience substantial weight loss, preventing the need for the second phase of DS.
Laparoscopic techniques revolutionized bariatric surgery, making procedures less invasive and recovery quicker. The first laparoscopic gastric bypass performed by Alan Wittgrove in 1994 exemplifies this leap in surgical innovation.The SG laparoscopic version was first performed in 1999.
Historically, the RYGBP is the best bariatric surgery for obese patients, but now being rivalled by the SG. The complication of RYGBP leads people to find less intricate and safer surgeries, the complication including internal hernias and anastomotic complications. Nowadays, SG has a lower risk of complication, and the mortality rate has become the more favorable option for the patients.

## Considerations
### BMI

Stomach reduction surgeries were highly recommended for patients who meet these criteria: BMI>40(Type 3 obesity), BMI>35(type 2 obesity), with specific comorbid conditions such as type 2 diabetes, hypertension, dyslipidemia, etc.

### Age

Elderly patients will face higher postoperative complications due to frailty of elderly patients. The adolescents who performed stomach reduction surgery showed better results and there is no negative impact on linear/puberty growth.

## Society and culture

The rising prevalence of lawsuits related to gastric bypass surgery is a legal concern in different countries. The causes are complex, including the immature characteristics of this technology and an increasing number of patients. In the future, the emergent patients who have stomach reduction surgery, long term complications and the number of lawsuits due to non-eligible surgery will increase.

## Contraindications

Stomach reduction surgery is not suitable for people with the following conditions:

### History of severe gastrointestinal disease

* Crohn's disease–RYGB surgery limited.
* Active peptic ulcers disease.
* Esophagitis in severe stage.

### Severe cardiovascular disease

* Heart failure
* Coronary artery disease
* Portal hypertension

### Cancer

Active cancer diagnosis

### Pregnancy

Pregnant (within 12-18 month)

### Psychiatric

Lower level of mental capacity or untreated mental disorders

### Blood clotting

Coagulopathy issue

## Type of surgery
### Gastric sleeve
#### Mechanism

The sleeve gastrectomy mechanism works by creating a narrow gastric lumen which restricts food intake and prevents receptive relaxation, alongside ongoing research into hormonal changes, and gastrointestinal motility.
The physical mechanism that will make the SG stand out to other bariatric surgery is its reduction towards the storage of the stomach significantly, allows patients to control their calories intakes.
The mechanism related to hormone regulation, SG can help to improve Insulin sensitivity, aiming for better glucose regulation and contributing to the remission of type 2 diabetes in many patients. The levels of gut hormones such as GLP-1 and PYY increase after operation of SG. GLP-1 enhances insulin secretion and has a satiety-inducing effect, while PYY helps reduce appetite. These hormonal changes are pivotal in the metabolic improvements observed after SG, including better control of blood sugar levels and reduced hunger.
SG will affect the metabolism and absorption of nutrients, hence causing an effect on nutrient dynamics. Postoperative observation shows patients' nutrients levels of Vitamin B1 and B12 have significantly declined, necessitating careful postoperative nutritional management to prevent deficiencies.
Research suggests SG surgery can alter the composition of the gut microbiota, which plays a role in obesity and metabolic health. Changes in the gut microbial community post-SG may influence energy harvest from the diet, impact inflammatory pathways, and affect the host's metabolic profile.
The key mechanism is gastrointestinal motility adjustment of SG surgery, which impacts the speed and efficiency of food processing. Studies have observed a modification in the pressure of the lower esophageal sphincter and an increase in intragastric pressure post-surgery, which collectively impact the gastrointestinal motility.

#### Techniques

* Hiatal Hernia Repair
During SG, identifying and repairing a hiatal hernia (HH) is a significant step that can influence the surgery's outcome, especially concerning gastroesophageal reflux disease (GERD) management postoperatively. The procedure involves dissecting the pars flaccida to open a plane between the right crus of the liver and the esophagus, performing an intrathoracic esophageal dissection, and identifying the left crus. A hiatal hernia repair is conducted, if necessary, with a posterior cruroplasty using a durable suture material. This step is vital as it ensures the proper positioning of the gastroesophageal junction (GEJ) and reduces the risk of postoperative GERD by securing the stomach below the diaphragm, preventing potential acid reflux.
* Bougie Sizing and Stapling Alongside
The insertion of a bougie during LSG is a crucial technique for guiding the creation of the gastric sleeve. The bougie, which ranges from 38 to 40 French in size, is inserted down to the pylorus under direct visualisation, serving as a mold around which the stomach is stapled and resected. This technique ensures that the sleeve is of uniform size and reduces the risk of to narrow a passage or obstruction post-surgery. Stapling begins 3-6 cm from the pylorus and proceeds upwards towards the angle of His, closely aligned with the bougie to create a narrow gastric tube. The careful placement and size of the bougie are instrumental in achieving optimal sleeve shape and function, minimising complications such as leaks or strictures.

#### Postoperative care

After 1-3 postoperative days, patients begin oral intake, contingent on a successful gastrografin leak test, and receive continuous metabolic monitoring. To reduce early respiratory risk, prophylactic measures such as oxygen support and ultrasound evaluations are employed.
Late postoperative care involves careful observation for anastomotic leaks, patient change to a clear liquid diet, and managing potential nausea and vomiting. After discharge, the focus shifts to dietary management, starting with a full liquid diet and gradually incorporating soft, solid foods. Monitoring includes regular check-ups for weight and blood pressure, along with comprehensive lab tests to ensure optimal recovery.

### Gastric bypass
#### Mechanism

Gastric bypass is the most frequently employed technique for weight reduction, the abnormal absorption in the intestines and the physical restriction of the stomach. The types of surgeries can be categorized by the effects and the changes made. Reconstruction of the small intestine in order to reduce the mucosal area which is used to absorb nutrients is called the Malabsorption operation. The jejunoileal bypass (JIB) is the most traditional technique for gastric bypass. This procedure has no limitations in the flow and processing of food; it only allows the transport of nutrients from the small intestine to the surrounding areas of intestine. The impact of weight loss is apparent and remarkable. Individuals who undergo ROUX-en-Y gastric bypass (RYGB) consume less snacks and meals compared to those who undergo JIB. The RYGB procedure has been proved to be the most effective medical treatment for type 2 diabetes and weight loss. After performing gastric bypass surgery, the two hormones related to obesity, leptin and insulin, fall in levels and while lose weight.

#### Techniques

Roux-en-Y (RYGB) offers two surgical approaches for processing: an open technique or the laparoscopic technique. The majority of cases are still performed with laparoscopy. The laparoscopic approach is a safe procedure that is associated with fewer problems resulting from wound inflammation.
There are three main areas of techniques for performing laparoscopic RYGB: (1) Anastomotic technique including Linear Circular stapler. 2) Alimentary limb configuration, such as Antecolic or Retrocolic and Antegastric or Retrogastric. 3) Limb-length of the bilio-pancreatic (BP) limb.

##### Linear stapling

This technique has two variations. 1) Perform the jejuno-jejunal (JJ) anastomosis, then act on the gastro-jejunal (GJ) anastomosis. 2) reverse the first process.

##### Jejuno-jejunal first

This technique is prevalent within gastric bypass surgery.

###### JJ Anastomosis

    In order to facilitate identification of duodenum-jejunum (DJ) flexion and Treitz ligaments, it will act on the Cephalic greater omentum using the laparoscopic staplers and Surgical energy device separate the mesentery. It also includes measuring the Roux limb between the distal end of the binding and the chosen length. For example, if the weight index is 40, the length should be 100cm.

###### Gastric pouch formation

    On the lesser curve of the stomach, a window will be opened between the second and third vessel at the perigastric border. The pouch will be formed using the laparoscopic stapling device. The orogastric tube which will be removed before the first launch of the stapler horizontally. The pouch is produced over the tube with next firings in another direction. These may need the mobilization to help further divide the stomach.

###### Gastro-jejunal anastomosis

    Gastrostomy is created at the specific angle (the part of the pouch with least blood supply). The separated alimentary limbs are translocated to the pouch antecolically. Enterotomy will processed within the jejunum. At the same time, between the gastric pouch and alimentary limb, the laparoscopic stapling devices create the single firing. According to the JJ anastomosis, the anastomotic defect closes with 2 continuously absorbed sutures. Finally, 50 ml of Dilute methylene blue dye is needed to assess leakage and ensure anastomotic integrity.

##### Other techniques

The Omega Loop Technique and Trans-abdominal technique employ different operating approaches along with different process orders. All of them will show positive weight loss results.

#### Recovery

The duration of the recuperation phase typically ranges from 2 to 4 weeks. The length of the period is dependent upon the self-perception of the patients and their future state of mental and physical ability. In order for patients to resume their normal activities, a minimum of 3-5 weeks recovery period is required. Doctors should determine the length of the recovery period based on a range of body mass index.

## Complication

Complications can be separated into 2 stages, early complication (within 30 days after surgeries) and late complications (after 30 days).

### Sleeve Gastrectomy (SG)

Early complication: Bleeding is present in approximately 5% of cases of sleeve gastrectomy. Symptoms can vary widely, ranging from gastrointestinal bleeding to internal bleeding. Venous thromboembolism (VTE) may occur, causing a decrease in flow through the splenic system, potentially leading to system collapse or death.
Late complications: They include gastric stenosis, nutrient deficiencies and Gastroesophageal reflux disease. For gastric stenosis, the symptoms are food intolerance and vomiting. For the gastroesophageal reflux disease, which due to post surgery changes of reduced lower esophageal sphincter tension and increased intragastric pressure. Patients may suffer from heartburn after eating or upper abdominal pain.

#### Roux-En-Y Gastric Bypass (RYGB)

Early complication of Roux-En-Y Gastric Bypass: Small bowel obstruction, which can be caused by the internal hernias due to the laparoscopic RYGB surgery techniques that were used. And it is life-threatening to patients since it is hard to diagnose through clinical or radiographic imaging. The symptoms included vomiting, abdominal pain and peritonitis. Common complications such as internal gastrointestinal hemorrhage (bleeding) and staple line leakage occur in both surgeries.
Late complication: For the anastomotic stricture, there is a 2.9%-23% chance for patients to experience gastrojejunal anastomosis. This complication more often occurs in the laparoscopic era than open RYGB surgery. Symptoms such as difficulty swallowing and vomiting.