BMJ Group Medical Reference
What is it?
Gastroplasty is a type of weight loss (bariatric) surgery. It means you have an operation to make your stomach smaller. There are two types: vertical banded gastroplasty and horizontal gastroplasty. Vertical banded gastroplasty is the more common type.
Here's what happens:
Your surgeon uses staples to divide your stomach into two parts, with a small opening between them. The top part, where food comes into your stomach, is smaller than the bottom part. This top part makes a small pouch.
Sometimes the surgeon puts a band around the lower part of the pouch to stop it stretching.
When you eat, the food goes into the small pouch, passes slowly through to the rest of your stomach and leaves through your intestine (the tube that takes food away from your stomach) as normal.
The small pouch can only take a few ounces of food. This means you should feel full sooner than usual. You will need to stop eating once you feel full.
Gastroplasty can be done as open surgery through one cut across your abdomen. Or you can have keyhole surgery with several small cuts. These types of surgery work equally well. But you're less likely to get problems with your wound after keyhole surgery. You're also likely to need less time in hospital with this type of operation. 
Most operations take at least an hour. Some may take several hours. Surgery takes longer if you have a lot of fat on your abdomen, as it takes time to cut through the fat and close it up afterwards. You'll have a general anaesthetic. This means you'll be asleep during surgery.
Your doctor may take out your gallbladder during the operation. Your gallbladder stores fluid called bile, which helps your body break down food. If you lose weight quickly you're likely to get gallstones. These are hard lumps that grow in your gallbladder. They can be very painful. Having your gallbladder removed when you have weight loss surgery is more common in the US than the UK.
How does it work?
Gastroplasty works by reducing the amount of food your stomach can hold. When you eat, the pouch quickly fills with food. So you feel full after eating only a little. This sends signals to your brain to tell it you're full sooner than usual. The idea is that you then stop eating.
What are the risks?
About a quarter of people get a problem during or shortly after gastroplasty. This could be bleeding, an infection, or lung problems. About 1 in 10 people had a problem that was bad enough to need another operation.
Infections are usually treated with antibiotics. But some infections cause an abscess. This is a pool of pus around the stomach. It can happen a few weeks after surgery. It may cause pain, fever, and a cough. An abscess usually needs to be drained. You may need another operation.