Sleeve Gastrectomy Surgery

Sleeve Gastrectomy Surgery

Sleeve gastrectomy is a surgical procedure used in the treatment of obesity. Obesity is a serious, chronic disease that is a growing worldwide concern affecting the health of millions of people. Obesity is defined as an excessively high amount of body fat in relation to lean body mass resulting from caloric intake that exceeds energy usage. Obesity is the second leading cause of preventable death following smoking.

To give you some basic information about how the gastrointestinal system is functioning and how sleeve gastrectomy surgery intervenes with this system, please read following points stated below:

The Gastrointestinal System

The gastrointestinal system is essentially a long tube running through the body with specialized sections that are capable of digesting material put in the mouth and extracting any useful components from it, then expelling the waste products.

Food after ingestion undergoes three types of processes in the body:

  1. Digestion
  2. Absorption
  3. Excretion

The entire gastrointestinal system is under hormonal control with the presence of food in the mouth triggering a cascade of hormonal actions. When food reaches the stomach, different hormones activate gastric secretion, increased gut motility, enzyme release etc. 

Nutrients from the gastrointestinal tract are not processed on-site but instead will be absorbed and taken to the liver through the blood circulation to be broken down further, stored, or distributed. 


Once food is chewed and mixed with saliva in the mouth, it is swallowed and passes down the esophagus. The esophagus has a stratified squamous epithelial lining (SE) which protects the esophagus from trauma. The submucosa lining (SM) secretes mucus from mucous glands (MG) which aid the passage of food down the esophagus. The esophageal wall muscle layer helps to push the food into the stomach by waves of motion called peristalsis.


The stomach is a ‘j’-shaped organ with two openings- the esophageal and the duodenal - and four regions- the cardia, fundus, body, and pylorus. Each region performs different functions including mixing of the food with digestive enzymes. The layer of mucus produced prevents the stomach from digesting itself.

The stomach’s functions are:

  • Temporary food storage
  • Control the rate at which food enters the small intestine
  • Antibacterial action
  • Fluidization of stomach contents
  • Preliminary digestion with pepsin, lipases etc.

Small Intestine

The small intestine is the site where most of the chemical and mechanical digestion is carried out, and where virtually all of the absorption of useful materials occurs. The whole of the small intestine is lined with an absorptive mucosal layer, with certain modifications for each section. The intestine also has a smooth muscle wall with two layers of muscle; rhythmical contractions force products of digestion through the intestine (peristalsis).

There are three main sections to the small intestine:

The duodenum forms a ‘C’ shape around the head of the pancreas. Its main function is to neutralize the chyme and to initiate further digestion; Brunner’s glands in the submucosa secrete alkaline mucus  and protects the surface of the duodenum.

The jejenum and the ileum are the greatly coiled parts of the small intestine, and together are about 4-6 meters long. The mucosa of these sections is highly folded (the folds are called plica), increasing the surface area available for absorption dramatically. 

Large Intestine

The large intestine is the last part of the digestive tube and the location of the terminal phases of digestion. It is the part of the digestive tube between the terminal small intestine and anus. Within the large intestine, three major segments are recognized:

The cecum is a blind-ended pouch that in humans carries a worm-like extension called the vermiform appendix. 

The colon constitutes the majority of the length of the large intestine and is sub-classified into ascending, traverse, and descending segments.

The rectum is the short, terminal segment of the digestive tube, continuous with the anal canal.

Functions of the Large Intestine:

  • Recovery of water and electrolytes from digested food:

A considerable amount of water and electrolytes like sodium and chloride remain and must be recovered by absorption in the large intestine. This is what goes wrong when you have diarrhea and constipation.

  • Formation and storage of feces:

As digested food passes through the large intestine, it is dehydrated, mixed with bacteria and mucus, and formed into feces.

  • Microbial fermentation:

Fermentation is the enzymatic decomposition and utilization of foodstuffs, particularly carbohydrates, by microbes. The large intestine does not produce its own digestive enzymes, but contains huge numbers of bacteria which have the enzymes to digest and utilize many substrates. 

These general information about our body’s digestive functioning is enough to form a logical framework of how the sleeve gastrectomy surgery change this functioning or which parts of this system is affected by this weight loss surgery. Before to go with the details; it would be helpful to give some more information about obesity.

1-) Body Mass Indicator

Body Mass Index (BMI) is the measure of body fat based on height and weight that applies to both adult men and women. BMI does not differentiate between body fat and muscle mass. Therefore, body builders and people who have a lot of muscle bulk will have a high BMI but are not overweight or obese. 

Overweight is defined as a Body Mass Index (BMI) of 25 to 29.9. Overweight refers to increased body weight in relation to height. 

Obesity is defined as a Body Mass Index (BMI) of 30 or higher and extreme obesity is a BMI of 40 or more. Extreme obesity is often referred to as Morbid Obesity due to the associated health risks. 


Less than 19 - Underweight

19 to 24.9 - Normal

25 to 29.9 - Overweight

30 to 39.9 - Obese

40 and above - Morbid Obesity

2-) Causes of Obesity 

Obesity could be a combination of the following:

  • The genes you inherited from your parents
  • How well your body turns food into energy
  • Your eating and exercising habits
  • Your surroundings
  • Psychological factors

 3-) Complications of Obesity

If you are obese, severely obese, or morbidly obese, you may have:

  • Shorter Life Expectancy (Compared to people of normal weight, obese people have a 50% to 100% increased risk of dying prematurely).
  • Obese people have more risk for: diabetes (type 2), joint problems (e.g., arthritis), high blood pressure, hearth disease, gallbladder problems, certain types of cancer (breast, uterine, colon), digestive disorders (e.g., gastroesophageal reflux disease, or GERD), breathing difficulties (e.g., sleep apnea, asthma), psychological problems such as depression, problems with fertility and pregnancy, incontinence 
  • Risks to psychological and social well-being: negative self-image, social isolation, discrimination
  • Difficulties with day-to-day living: Normal tasks become harder when you are obese, as movement is more difficult; You tend to tire more quickly and you find yourself short of breath; Public transportation seats and car seats may be too small for you; You may find it difficult to maintain personal hygiene. 

1-) Surgical Procedure:

Sleeve gastrectomy surgery is a restrictive surgical procedure. It is restrictive in the sense that it ‘restricts’ how much for the stomach can hold. A sleeve gastrectomy is used to help people who are severely obese (BMI 40+ or BMI 35+ with other health conditions) to lose weight and improve their health. Losing weight should help to lower the risk of developing medical problems associated with obesity (e.g. high blood pressure, diabetes, arthritis, breathing problems and asthma). The sleeve gastrectomy makes your stomach smaller and should change the amount you can eat at your meals, which will help you to lose weight. It is not a reversible procedure. Usually people considering a sleeve gastrectomy will have already tried many non-surgical options available to help them to lose weight.

The surgery is usually done laparoscopically, commonly known as keyhole surgery. The operation involves removing approximately 75 per cent of your stomach, leaving behind a narrow tube (sleeve) which becomes your new stomach. After the surgery food will follow the normal route into the smaller stomach and then on into the small intestine. The operation also alters some of the hormone signals from the stomach and intestine to parts of the brain that control body weight. Following this operation, many patients report that they feel less like eating and feel fuller sooner and for longer after a meal. As the size of your stomach has been reduced, the size of your meals will need to be reduced to be appropriate for your new small stomach. Your reduced portion size combined with low fat, low sugar choices will help you to lose weight. The amount of weight you are able to lose and keep off after surgery will depend also on the exercise you do and eat a healthy diet.

2-) Advantages of the Sleeve Gastrectomy Surgery:

  • Reduced stomach volume increases feeling of fullness
  • Stomach functions normally allowing most foods to be eaten, just in smaller amounts
  • Stomach portion that produces hunger stimulating hormone (Ghrelin) is removed
  • Can be performed laparoscopically
  • Less operative time than bypass surgeries
  • Less hospital stay than bypass surgeries
  • No foreign bodies used such as in band surgery

3-) Disadvantages of Sleeve Gastrectomy Surgery:

  • Potential is higher for inadequate weight loss or weight regain compared to intestinal bypass surgeries
  • Irreversible
  • Considered a temporary treatment for obesity unless second stage (bypass) is performed
  • Potential for dilation of the sleeve affecting weight loss
  • Long term results have not been evaluated

4-) Risks & Complications

  • As with any surgery there are potential risks involved. The decision to proceed with the surgery is made because the advantages of surgery outweigh the potential disadvantages.
  • It is important that to read all consent forms carefully, discuss them with the surgeon and take all risks & possible complications into consideration before the surgery.

5-) What are the available alternatives? 

It is important for you to know that the procedure recommended is based on your specific medical history and dietary history. 

The aim of this article is to give you a general information about the surgical intervention in question. You need to make more research about possible complications and risks of this selected procedure in order to make an informed decision. Please note that complications occur more frequently with patients who are obese, smoke, and have a history or lung or other chronic underlying medical conditions.

Smokers are recognized to have a significantly higher risk of post operative wound healing problems with a subsequently higher potential of infection as well as operative and post operative bleeding. Patients should discontinue smoking for two weeks before and two weeks after surgery. Although it helps to stop smoking before and after surgery, this does not completely eliminate the increased risks resulting from long­ term smoking. Smoking also has a long term adverse effect on the skin and ageing process. 



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