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What is a Roux-en-Y Gastric Bypass (RYGB)?

A Roux-en-Y Gastric Bypass (RYGB) involves dividing the stomach to create a small pouch at the top. A segment of the small intestine is then connected to this pouch. There is a connection between the 2 limbs of the small bowel further down (called the jejuno-jejunal anastomosis) to allow mixing of gastric juice and food to allow digestion. Food is hence bypassed from the larger portion of the stomach and the first part of the small intestine (call the duodenum). It is used to help people to lose weight and improve their health.


Losing weight lowers the risk of developing medical problems associated with obesity, such as heart attack, high blood pressure, diabetes mellitus, arthritis, obstructive sleep apnea, fatty liver, back pain, knee pain and ankle pain. This is a very effective operation to help improve Type 2 Diabetes Mellitus. The diabetic control can be improved and the need for medications reduced.

What are the benefits of a Roux-en-Y Gastric Bypass (RYGB)?

After the surgery, food will enter the small stomach pouch from the oesophagus and then directly into the small intestine (Roux limb), hence bypassing the larger portion of the stomach. It will mix with the gastric juice to allow digestion after the jejuno-jejunal anastomosis. 

A patient after Roux-en-Y Gastric Bypass (RYGB) will feel less hungry and fuller sooner and for longer after a meal.  The need for blood pressure or diabetes medication may be reduced, but still able to achieve a better control compared to before the operation. Risk of heartburn is lower in gastric bypass patients compared to those who underwent sleeve gastrectomy. 

The surgery is done laparoscopically, commonly known as “keyhole” surgery. This means that you will be up and about soon after surgery and should make a speedy recovery.

Find out more on how this Minimally Invasive Surgery - RYGB can benefit you!

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How much weight can you expect to lose?

You can lose up to 50% - 80% of your excess weight (EWL) or 25-35% of your total weight (TWL) in the first 12–18 months following surgery. However, an excess weight loss of 100% or more is not uncommon in patients who do intensive exercising. The amount of weight you are able to lose and keep off after surgery will depend also on the lifestyle changes that you make, such as increasing the amount of exercise you take and eating a healthy diet.

What are the risks of a Roux-en-Y Gastric Bypass (RYGB)?

As with all major surgery, Roux-en-Y Gastric Bypass (RYGB) has some risks. These risks vary according to your age and other illnesses you may have. They are mainly general anaesthesia risk and specific operation risk associated with the operation. Dr Tan will go through the details with you in the clinic. 

The risk of death within the first 30 days after surgery is estimated to occur in less than 0.5% (or 1 in every 200 patients) having this operation. Other complications happen in less than 5% of patients (or 1 of every 20 patients).

Patient Journey

The day of the operation

  • You will usually be admitted to the hospital on the day of your operation.

  • There may be instances where you may be admitted several days before the operation.

  • You should not have anything to eat or drink 8 hours before your surgery, although you may drink plain water up until 2 hours before.

  • Once your admission is complete, you will then go to operating theatre waiting area where you will meet your anaesthetist.

  • After which you will then enter the operating theatre and the anaesthetist will put you to sleep.

  • You will also be given an intravenous drip so you can have fluids during the operation.

What should you expect after the procedure?

The first few hours after the operation

You will wake up in a recovery room where nursing staff will monitor you for any complications. You will have a drip and also be wearing stockings and have a pumping device on your legs to prevent blood clots. 

As soon as you are fully awake and comfortable, you will be transferred to either the surgical ward, high dependency or the intensive care unit or where your relatives can visit you. You will be able to have sips of water and some painkillers to control any pain. 

You are encouraged to get out of bed as soon as possible after surgery. This helps to reduce the chance of post-operative complications such as blood clots in the legs or chest infections.

The day after the operation

You may be scheduled for a swallow test by Dr Tan. After which you will be able to have some fluids. Your drip will be removed when you are drinking enough to keep you hydrated.

The following few days after the operation

You should start to feel better very quickly after the operation and will be able to move around on your own. You will need to drink an average of 1.5L to 2.5L of fluids daily. We will have a dietician to guide your post-operative diet. 2-3 days after surgery you will be able to go home.

At discharge

Pain and Medications

You will be given oral pain medications to go home. You will also be given anti-acid medications. If you have been taking medication to control your blood pressure or diabetes, these will be reviewed before your discharge. In most cases these can be reduced or sometimes stopped all together. Please make sure you are clear about this before you leave the hospital.


The small incisions made for your surgery may be covered with small plasters upon discharge. Dr Tan will review the wounds when you see him in the clinic.

Eating and Drinking after operation

You will be given a diet information sheet. Our dietician will help guide you along for your post-operative diet.


You will be able to walk straight after surgery. Try to go for a walk every day, gradually increasing the distance as you feel able. You will be given hospitalization leave. It is advisable to avoid heavy lifting for at least 1 month after abdominal surgery.

Women of childbearing age must not become pregnant for at least one year following bariatric surgery.

After one year: if you are planning a pregnancy, please inform Dr Tan and he will guide you accordingly.

Follow up schedule

You will be given an appointment to see Dr Tan in his clinic for follow up. Initially after the surgery, there will be closer follow up, after which the periods for follow up will then be further spaced out.

Complications that can occur soon after surgery

Wound infection: this can usually be treated with a course of antibiotics and does not require hospital admission.

Bleeding: You will be monitored carefully for signs of bleeding. If occurs, it can be often managed conservatively and occasionally it may require transfusions. Exceptionally the Dr Tan will need to perform surgery to stop the bleeding.

Blood clots in the legs or the lungs (DVT/PE): To prevent blood clots from forming you will be given an injection just before the operation to thin the blood. During and immediately after your operation, you will wear special stockings to prevent clots from occurring. You will be asked to ambulate early to minimize the risk of such clots.

Smoking significantly increases the risk of clotting. If you are a smoker, you will be advised to stop smoking before surgery.

Leaks from staple lines: This postoperative problem is rare but serious and may require emergency surgery. A leak is usually caused by a failure of the natural healing process as all staple lines are checked at the end of the operation. If this happens, your hospital stay will be longer. Sometimes this will heal without further surgery. In the worst-case scenario, Dr Tan may decide to take you back to operating theatre to control the leak and perform additional measure to help with your recovery.

Long term complications after Roux-en-Y gastric bypass

Long term problems are uncommon but can include:

  • The risk of additional surgeries after Roux-en-Y gastric bypass is generally higher than sleeve gastrectomy

  • “Dumping” of food may occur, especially after eating foods with high content of sugar or fat. There are early and late dumping syndromes. Dr Tan and his dietician will help you along should you experience these symptoms.

  • Hair loss or thinning in the first six months. This is a temporary side effect of the rapid weight loss and it will improve with time.

  • Gallstones. Gallstone formation can be found in up to 30% of post bariatric surgery patients. Discuss your options with Dr Tan. 

  • Nutritional deficiencies. It is highly encouraged that you take multi-vitamin supplements after Roux-en-Y gastric bypass, due to lesser absorption of nutrients after surgery. Dr Tan and dietician in the multi-disciplinary team will guide you in your vitamin supplementation during your follow up visits in Dr Tan’s clinic.

  • Port site hernias of the abdominal wall 

  • Internal hernias. Risk of internal hernia happening is low, but one needs to be aware of it. Symptoms to look out for include severe abdominal pain, vomiting. Such symptoms can happen many years after the bypass surgery. Severe cases can lead to obstruction of small bowel, sometimes even small bowel compromise requiring resection. Please head to the A&E immediately in the event of emergency and get the A&E doctor to contact Dr Tan. 

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