Definition and Overview

Gastric bypass surgery is a medical procedure that divides the stomach into two parts (a smaller upper pouch and a larger lower pouch) and reroutes the small intestine so that it is connected to both pouches. This procedure reduces the functional volume of the stomach as well as alters the body’s physical and physiological response to food.

This procedure is also known as Roux-En-Y gastric bypass surgery. It is one of many different types of bariatric surgery, which refers to all types of surgical techniques used to treat patients who are considered to be morbidly obese. Aside from gastric bypass surgery, another type of bariatric surgery is called gastric bypass sleeve surgery, which not only divides the stomach into two parts but also removes up to 80% of the stomach to permanently reduce its size.

Who Should Undergo and Expected Results

Gastric bypass surgery is used to treat patients who suffer from morbid obesity, those who are unable to lose weight, or sustain long-term weight loss through dietary techniques.

Traditionally, patients who are categorised as seriously obese are those who weigh at least 100 pounds more than their ideal body weight. However, the criteria have been updated and the term now applies to patients whose body mass index (BMI) is 40 or higher. Patients whose BMI is 35 or higher are also considered as seriously obese if they are already suffering from comorbid conditions. Comorbidity means that there's at least one additional disorder or disease that occurs simultaneously with the primary medical condition. Obesity can cause diseases such as type 2 diabetes, sleep apnoea, and hypertension, among many others.

A gastric bypass procedure is expected to result in dramatic weight loss and reduction of comorbidities. It can also reduce the long-term mortality rate of patients by as much as 40%.

How is the Procedure Performed?

Gastric bypass surgery is now commonly performed using minimally invasive methods. Also referred to as laparoscopic gastric bypass surgery, this technique is known to be equally effective as traditional open surgery but is much safer. Instead of a long incision in the abdomen, this limited access technique uses several significantly smaller incisions where a surgical telescope and specialised surgical instruments are inserted. The surgical telescope has a tiny camera attached to it that transmits live images to a video screen, giving the surgeon a clear view of the surgical site.

The first part of the procedure involves creating a small thumb-sized pouch in the upper part of the stomach, which can only hold about 15-30 mL or 1-2 tbsp in volume. The surgeon achieves this by creating a wall between the smaller pouch and the remaining part of the stomach or by completely dividing the stomach into two separate parts. The latter technique is sometimes used to prevent the stomach from fusing together again through a fistula. Whichever technique is used, the remaining part of the stomach is bypassed. This effectively reduces the volume of food that the patient can consume.

After the stomach is partitioned or divided, the surgeon moves on to the second part of the surgery, in which the gastrointestinal (GI) tract is reconstructed so both pouches of the stomach can drain properly.

While the general manner through which the procedure is performed remains the same, there are many variants of gastric bypass surgery. The specific variant used may affect the cost of gastric bypass. These include:

  • Gastric bypass, Roux-en-Y (RYGB proximal) – This is the most commonly used variant and is also the most common type of bariatric surgery performed. During this type of surgery, the small intestine is divided 18 inches below the lower stomach (upper proximal end of the small intestine) and is configured into a Y shape. This enables food to flow from the smaller stomach pouch through the Roux limb, as well as from the larger stomach pouch.

  • Gastric bypass, Roux-en-Y (RYGB, distal) – In this technique, the Y intersection is moved to the lower part of the small intestine (distal portion). This does not only reduce the functional volume of the stomach but also reduce the amount of nutrients that the body can absorb from food. The distal positioning allows fats and starches to pass into the large intestine without getting absorbed into the body.

  • Mini gastric bypass – First used in 1997, a mini gastric bypass creates a narrow tube out of the right part of the stomach. The small intestine is then brought up and connected to the said tube. The connection is usually made 180 cm from where the small intestine begins. This simpler technique is used as an alternative to the Roux-en-Y procedure, and can also lower gastric bypass costs. It also has a lower risk of complications and a greater chance of bringing about sustained weight loss.

  • Endoscopic duodenal-jejunal bypass – This recent development involves implanting a duodenal-jejunal bypass gastric liner between the duodenum and the mid-jejunum. This means that partially digested food does not enter the first part of the small intestine.

Despite the common use of laparoscopic gastric bypass, this type of procedure is considered to be one of the most difficult procedures to perform in a minimally invasive manner. Nevertheless, its many benefits help sustain its popularity. Due to the smaller size of incisions used, patients experience reduced bleeding, pain, and discomfort. Thus, they enjoy a shorter hospital stay and recovery time. They also experience less scarring and face a lower risk of developing an incisional hernia.

Possible Risks and Complications

A gastric bypass procedure comes with its own set of risks and complications. Studies show that 15% of patients experience post-surgical complications. Many also require gastric bypass revision or revisional surgery. Out of this number, 0.5% dies within six months due to complications.

Moreover, the specific variant or technique used does not only affect the gastric bypass surgery cost, it also affects the patient’s risk of experiencing complications. For example, an endoscopic duodenal-jejunal bypass is linked to an increased risk of gastrointestinal bleeding and abdominal pain. There is also a possibility that the device, or the implanted bypass liner, will eventually move out of its position. Known as device migration, this complication can only be resolved by removing the device, which negates the effects of the procedure.

To ensure optimum surgical outcomes and prevent serious complications, patients are advised to undergo a comprehensive medical evaluation before undergoing surgery.

References:

  • Inge TH, Courcoulas AP, Jenkins TP, et al. “Weight loss and health status 3 years after bariatric surgery in adolescents.” The New England Journal of Medicine. 2016; 374:113-123. http://www.nejm.org/doi/full/10.1056/NEJMoa1506699#t=article

  • Pories WJ. “Bariatric surgery: Risks and rewards.” J Clin Endocrinol Metab. 2008 Nov; 93(11 Suppl 1): S89-S96. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2729256/

  • Griffith PS, Birch DW, Sharma AM, Karmali S. “Managing complications associated with laparoscopic Roux-en-Y gastric bypass for morbid obesity.” Can J Surg. 2012 Oct; 55(5): 329-336. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3468646/

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