by EBSCO Medical Review Board
(Bariatric Surgery; Weight-Reduction Surgery)


Roux-en-Y gastric bypass is surgery to decrease the structure and size of the stomach and attach it to a small part of the intestine.

Reasons for Procedure

This surgery is done to treat severe obesity when other methods have not helped. It makes the size of the stomach smaller to cause weight loss by:

  • Restricting food intake—creates a small pouch to serve as the stomach, so a person cannot eat as much
  • Making the body unable to absorb as many calories from food—bypasses the first part of the small intestine, where many of the calories from food are usually absorbed

In addition to helping a person lose weight, this surgery may also:

  • Improve physical function
  • Lower high blood pressure
  • Lower blood glucose levels
  • Lower cholesterol levels
  • Lower the risk of heart disease
  • Reduce sleep apnea

Possible Complications

Problems are rare, but all procedures have some risk. The doctor will go over some problems that could happen, such as:

  • Excess bleeding
  • Problems from anesthesia, such as wheezing or sore throat
  • Infection
  • Blood clots
  • Lasting nausea and vomiting
  • Diarrhea and abdominal cramping
  • Breakdown of the staples, allowing leakage of stomach juices into the abdomen
  • Gallstones
  • Hernia
  • Bowel obstruction
  • Heart attack

Things that may raise the risk of problems are:

  • Smoking
  • Drinking alcohol
  • Chronic diseases, such as diabetes

What to Expect

Prior to Procedure

The bariatric surgery team will meet with you to talk about:

  • Anesthesia options
  • Any allergies you may have
  • Current medicines, herbs, and supplements that you take and whether you need to stop taking them before surgery
  • Fasting before surgery, such as avoiding food or drink after midnight the night before
  • Whether you need a ride to and from surgery
  • Specialists you may need to see, such as a registered dietitian
  • Tests that will need to be done before surgery, such as mental health counseling and an endoscopy


You will be given general anesthesia . You will be asleep.

Description of Procedure

Several small incisions will be made in your abdomen. Gas will be pumped in to inflate your abdomen and make it easier to view the stomach. A thin, lighted tool with a tiny camera will be inserted through an incision. A monitor will be used to view the images. Other tools will be inserted into other incisions.

Surgical staples will be used to create a small pouch at the top of the stomach. The small pouch can hold only 1 cup of soft, moist, and well-chewed food. A normal stomach can hold 4 to 6 cups. Next, the small intestine will be cut and attached to the new pouch. Food will now move from the new stomach pouch to the middle section of the small intestine. It will skip the lower stomach and the upper section of intestine. Lastly, the upper section will be attached to the middle section of the small intestine. This will allow fluid that the lower stomach makes to move down the upper section of the small intestine and into the middle intestine. The incisions will be closed with stitches or staples. A bandage will be placed over the area.

In some people, the doctor may need to switch to open surgery.

Roux-en-Y Gastric Bypass
Copyright © Nucleus Medical Media, Inc.

How Long Will It Take?

About 2 hours

Will It Hurt?

Pain and swelling are common in the first 1 to 2 weeks. Medicine and home care can help.

Average Hospital Stay

You will be in the hospital for 2 to 5 days. If you have any problems, you may need to stay longer.

Post-procedure Care

At the Hospital

After the procedure, the staff may:

  • Take an x-ray to look for leaks from the stomach pouch.
  • Give you pain medicine.
  • Give you clear liquids
  • Encourage you to begin walking
  • Teach you how to use an incentive spirometer to prevent breathing problems
  • Give you compression stockings to promote blood flow to your legs

During your stay, the hospital staff will take steps to lower your risk of infection, such as:

  • Washing their hands
  • Wearing gloves or masks
  • Keeping your incisions covered

There are also steps you can take to lower your risk of infection, such as:

  • Washing your hands often and reminding visitors and staff to do the same
  • Reminding staff to wear gloves or masks
  • Not letting others touch your incisions
At Home

It will take a few weeks for the incisions and muscles to fully heal. Physical activity will be limited during this time. You will need to ask for help at home and delay your return to work.

Dietary changes, regular exercise, and counseling will need to be part of your recovery and lifelong weight loss plan.

Problems to Look Out For

Call the doctor if you are not getting better or you have:

  • Signs of infection, such as fever and chills
  • Redness, swelling, excessive bleeding, or discharge from the incision
  • Pain that you cannot control with medicine
  • Pain and swelling in your feet, calves, or legs
  • Lasting nausea or vomiting
  • Blood in your stool
  • Pain, burning, urgency or frequency of urination, or persistent bleeding in the urine
  • Cough
  • Shortness of breath
  • Chest pain
  • New or worsening symptoms

If you think you have an emergency, call for medical help right away.


American Society for Metabolic and Bariatric Surgery 

National Institute of Diabetes and Digestive and Kidney Diseases 


HealthLink BC 

Weight Loss Surgery 


Bariatric surgery. Merck Manual Professional Version website. Available at: Accessed September 28, 2021.

Bariatric surgery in adults. EBSCO DynaMed website. Available at: Accessed September 28, 2021.

Gastrict bypass surgery. Columbia University Medical Center website. Available at: Accessed September 28, 2021.

Obesity surgery. Cleveland Clinic website. Available at: Accessed September 28, 2021.

Risks of gastric bypass surgery: anastomotic leaking. Johns Hopkins Medicine website. Available at: Accessed September 28, 2021.

Weight-loss (bariatric) surgery. National Institute of Diabetes and Digestive and Kidney Diseases website. Available at: Accessed September 28, 2021.

Revision Information

  • Reviewer: EBSCO Medical Review Board Marcin Chwistek, MD
  • Review Date: 07/2021
  • Update Date: 09/28/2021