Mini Gastric Bypass (One Anastomosis)

What is a mini gastric bypass?

A mini gastric bypass (MGB) is a type of weight loss surgery. It involves a surgeon making your stomach narrower and connecting it in a loop to the middle of your small intestine.

A smaller stomach limits how much food you can eat. The intestinal loop connection allows food to skip the first part of your intestine. This decreases how many calories and nutrients your body digests and absorbs.

MGB is different from traditional gastric bypass surgery (also called Roux-en-Y) because of how your stomach and small intestine connect. The traditional method makes your stomach smaller and reroutes your stomach and small intestine using two connection points. With a mini gastric bypass, there is just one connection point. This makes the surgery less complex.

This procedure is sometimes called one anastomosis or omega loop bypass.

How mini gastric bypass works

A mini gastric bypass works in these ways:

• Restricts food intake: The procedure creates a small, tube-like stomach. This limits how much food you can eat.
• Reduces food absorption: Your stomach connects to the middle of your small intestine. It bypasses the first part of your intestine. This limits how many calories your body digests and absorbs.
• Changes hormones: It decreases ghrelin (the hunger hormone) and increases GLP-1 in your body. This reduces your appetite and increases how full you feel.

These effects can lead to significant weight loss for people with Class III obesity and/or obesity-related health conditions.

How do I prepare for a mini gastric bypass?

Your healthcare provider will give you specific instructions on how to prepare. You may have to go to appointments to make sure you understand the procedure and recovery process.

Other things you may expect include:

• Having blood tests, imaging tests and/or a physical exam to make sure you’re healthy enough for surgery
• Eating a low-calorie diet before surgery, which can include a liquid diet for a few days just before the procedure
• Avoiding certain medications and/or quitting smoking

What happens during a mini gastric bypass?

A mini gastric bypass uses minimally invasive techniques, like laparoscopic or robotic surgery. These methods use small cuts, which help you recover faster.

You can expect the following to happen during the procedure:

1. A healthcare provider will place an IV in your arm to give you medication and anesthesia.
2. Once you’re asleep, your surgeon makes five or six small cuts (incisions) in your belly. They use these to insert the tools needed during surgery.
3. Your surgeon reshapes your stomach into a long, narrow pouch that holds less food.
4. They attach the pouch to a loop of the middle portion of the small intestine. Food bypasses the first portion of the intestine.
5. All surgical tools are removed. They close the incisions with stitches.
6. You’re taken to a recovery room for monitoring.

How long does this procedure take?

It takes about two hours. You’ll need to spend one to two days in the hospital afterward.

What are the advantages and disadvantages?

The main advantage is that it’s effective for weight loss. Losing weight can help with many health conditions, like Type 2 diabetes, high cholesterol, high blood pressure and sleep apnea.

Some of the advantages of a mini gastric bypass compared to a traditional gastric bypass are:

• Faster and less complex surgery
• Less risk of bowel obstruction, leaks from the surgical connection and hernias

Some of the main risks and disadvantages are:

• Higher risk of bile reflux
• Risk for complications, like bleeding and infection
• Lifelong need for vitamins to replace nutrients you don’t absorb
• Ulcers forming where your stomach and intestine connect
• Dumping syndrome (food moves too fast from your stomach into your intestine)

What can I expect after mini gastric bypass?

You’ll need a few weeks to recover after the procedure. Your healthcare provider can let you know what to expect. You may need to avoid strenuous activity for up to six weeks. It may take up to 12 weeks to go back to a typical diet.

Your provider will monitor you — usually for the rest of your life — to make sure the surgery is working as expected. They’ll check for vitamin and mineral deficiencies. They’ll work with you to adjust your diet and supplements to help you stay healthy.

How effective is mini gastric bypass?

It’s one of the more effective bariatric surgeries for weight loss. One study showed that people with a mini bypass had up to 73% excess weight loss compared to 60% for traditional bypass after five years. Your results may be different. Talk to your healthcare provider about what you can expect based on your health history.

When should I call my healthcare provider?

Contact your provider if you have any of the following after surgery:

• Fever of 101 degrees Fahrenheit (38.3 degrees Celsius) or higher
• Severe belly pain
• Swelling or leakage from an incision in your belly
• Severe diarrhea or vomiting
• Trouble breathing

You’ll need several follow-up appointments with your provider to make sure the surgery was successful and that you’re getting the nutrients you need. It’s important that you don’t miss or skip these appointments.