Gastric bypass surgery, also known as Roux-en-Y gastric bypass (RYGB), is a a type of bariatric surgery that reduces the size of the stomach and reroutes the small intestine, leading to decreased food intake and nutrient absorption and resulting in weight loss of up to 80% of initial body weight.

Gastric bypass surgery is indicated for people with a BMI greater than 35 kg/m², especially in those with other serious health conditions related to overweight and obesity, when diet and exercise are not enough. It may also be indicated when other weight loss procedures, such as gastric band and gastric balloon, have proven unsuccessful.

Gastric bypass surgery is one of the most common types of bariatric surgery performed by gastrointestinal (GI) surgeons and may be covered by insurance.

Indications for surgery

Gastric bypass surgery is indicated for the treatment of obesity in the following:

BMI of 40 kg/m² or greater;
BMI between 35 kg/m² and 40 kg/m² in the presence of other health conditions such as diabetes, high blood pressure, or sleep apnea;
Other weight loss procedures have been unsuccessful, such as gastric band or gastric balloon.

Gastric bypass surgery may also be indicated for those in which diet and exercise were not enough to achieve meaningful weight loss and improve health conditions.

Surgical procedure

Roux-en-Y gastric bypass is a complex surgery performed under general anesthesia by a GI surgeon. The procedure usually takes around 2 hours.

Gastric bypass surgery may be done in the conventional way, involving a large abdominal incision, or laparoscopically. The laparoscopic procedure involves 4 to 6 small incisions in the abdomen to allow a tiny camera and surgical instruments to pass through into the abdominal cavity. The camera allows for visualization of the abdominal cavity while the surgeon operates.

Gastric bypass surgery involves the following steps:

Incisions are made in the stomach and the small intestine: an incision is made in the stomach, close to the esophagus, to separate the stomach into two parts: a smaller stomach in the form of a pouch and a larger portion. This means that the stomach is no longer able to store food as it was before. An incision is also made in the small intestine at the jejunum;
The small intestine is reattached to the new stomach pouch: the lower part of the small intestine is attached directly to the small stomach pouch, allowing food to pass from the stomach into the intestines;
The small intestine still attached to the larger portion of the stomach is rerouted: the upper portion of the small intestine is reattached further down to allow food from the stomach pouch to mix with the digestive enzymes from the larger portion of the stomach, aiding in digestion.

Laparoscopy is the technique used most often for gastric bypass surgery, as it allows for a shorter recovery time and decreases the risk for infection.

Recovery after surgery

Recovery from gastric bypass surgery usually involves a 2 to 3 day hospital day following surgery. During this time, patients are monitored by the surgeon, an anesthesiologist, and the nursing staff. IV fluids will be given to help with hydration and recovery post surgery, and analgesics will be given as needed for pain. Bandages will be applied to protect the incision and replaced by the nursing staff as needed.

Patients are not allowed to eat during the first two days post surgery. After this time, patients will progress to a clear liquid diet, as indicated by a doctor. The diet will gradually progress to include thicker liquids and solids that will help with recovery as well as adjustment to the new dietary restrictions post surgery. This phase may last for about three months following surgery.

Care instructions for home

Instructions for recovery at home following discharge from the hospital include:

Taking medications at the correct times as indicated by your doctor;
Having bandages replaced at the doctor's office or clinic one week after surgery;
Following a special diet as outlined by a dietitian, which may evolve over the course of several weeks;
Staying hydrated by drinking an adequate amount of fluids, as indicated by your doctor, being sure to avoid drinking with meals and within 30 minutes of a meal;
Consuming food and drinks slowly and in small amounts to prevent nausea, vomiting, diarrhea, and dizziness;
Avoiding alcohol and caffeinated beverages, like coffee, black tea, and green tea;
Taking supplements as directed by your doctor, such as iron, calcium, and vitamin B12;
Taking medications that prevent acid production, such as omeprazole, before meals to protect the stomach (as directed by your doctor);
Getting up for short walks every hour to prevent blood clots from forming in the legs. Avoid long walks and heavy lifting;
Avoiding driving for the first 6 weeks following surgery and making sure not to buckle your seat belt over your scar;
Avoiding strenuous activities for the first 6 weeks post surgery.

Recovery from gastric bypass surgery is slow and may take anywhere from 6 months to 1 year, with the most rapid weight loss noted during the first 3 months post surgery.

Aesthetic procedures like abdominoplasty may be indicated 1 to 2 years after surgery for the removal of excess skin, as changes to the body become more apparent over time.

Advantages and disadvantages

The advantages and disadvantages of gastric bypass surgery include:

Advantages	Disadvantages
Rapid weight loss related to dietary restrictions and decreased nutrient absorption, typically around 80% of initial body weight; More rapid and consistent initial weight loss; Improved glucose values in people with diabetes; Improved blood pressure in people with hypertension; Decreased cholesterol and triglycerides, which lowers the risk of cardiovascular disease; Decreased risk of venous thromboembolism; Improvements in sleep apnea and other sleep problems; Relief from gastroesophageal reflux disease (GERD); Improvements in back and joint pain related to carrying excess weight; Improvements in respiratory issues such as asthma attacks; Improved quality of life; While difficult, the procedure is reversible.	Risk for weight loss failure; Complex surgery involving permanent changes to gastrointestinal anatomy; Higher risk of gastrointestinal, nutritional, and psychological complications; Longer recovery time; Risk for nutritional deficiencies related to decreased absorption of vitamins and minerals in the intestines; Regaining the weight lost; Lifelong dietary restrictions.

It is important to talk to your doctor before surgery about the risks and benefits of gastric bypass surgery as well as any alternatives to the procedure.

Learn about other types of bariatric surgery.

Possible risks

The main risks of gastric bypass surgery are localized infection in the area of the incision, temporary bowel obstruction, bleeding, and intra-abdominal infection.

Other complications may occur that happen more frequently in patients who do not adhere to dietary instructions post surgery. These include:

Dumping syndrome with symptoms like nausea, intestinal colic (cramps), diarrhea, and fainting;
Dehydration from not drinking enough fluids as directed by a doctor;
Constipation related to a lack of physical activity, inadequate fluid intake, and/or a low fiber diet;
Chronic anemia, mainly related to malabsorption of vitamin B12.

Make sure to keep all follow up appointments as scheduled and complete all tests as ordered by your doctor. This will be important in monitoring for any health conditions and reducing the risk of complications post surgery.

Gastric bypass vs gastric sleeve

Both gastric bypass and gastric sleeve are types of bariatric surgery, however there are some differences. Gastric bypass surgery involves reducing the size of the stomach and rerouting the small intestine, decreasing food intake and nutrient absorption.

Gastric sleeve is a surgical technique in which the surgeon removes a large portion of the stomach, resulting in weight loss through reduced food intake. Alternations are not made to the small intestine, however, so there is no change in nutrient absorption.