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What is a Sleeve Gastrectomy?

A sleeve gastrectomy is a life-changing operation. 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. 


A sleeve gastrectomy makes your stomach smaller and should change the amount you can eat at your meals which will help you to lose weight. It is not a reversible procedure. This is the most common type of bariatric surgery performed in the world and Singapore currently.

How does it work?

The operation involves removing approximately 70% - 80% of your stomach, leaving behind a narrow tube (sleeve) that becomes your new stomach. After the surgery, food will follow the normal route into the smaller stomach and then into the small intestine. 

The operation also alters some of the hormone signals from the stomach and intestine to parts of the brain that control body weight: many patients report that following this operation they feel less like eating and feel fuller sooner and for longer after a meal. 

As the size of your stomach has been reduced, the size of your meals will need to be reduced to be appropriate for your new small stomach. Your reduced meal portion size, combined with low fat and low sugar choices, will help you lose weight and maintain weight loss. 

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.

How much weight can you expect to lose?

You can lose up to 40% - 80% of your excess weight (EWL) or 20-30% 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 can lose and keep off after surgery will also depend on the lifestyle changes you make, such as increasing the amount of exercise you take and eating a healthy diet.

What are the risks of a Sleeve Gastrectomy?

As with all major surgery, sleeve gastrectomy 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.

Find out more from Dr Tan on how you can improve your metabolic health with Sleeve Gastrectomy surgery.

Call or WhatsApp us now to get an appointment with Dr Tan


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 completed, 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 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 altogether. 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 the 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 Sleeve Gastrectomy Surgery

Long term problems are uncommon but can include:

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  • Narrowing (stricture) of the sleeve which can make eating and drinking more difficult. This may require treatment with an endoscopy, or conversion to a bypass.

  • Reflux symptoms. Some patients may experience heartburn symptoms after sleeve gastrectomy. Some may settle with medications. For severe reflux symptoms, there may be a need to do further investigations to find the cause. Rare occasions may include the need to convert to a Roux-en-Y gastric bypass. (RYGB)

  • 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. 

  • Port site hernias of the abdominal wall 

  • Nutritional deficiencies. You may be advised to take multi-vitamin supplements after surgery during your routine follow up with Dr Tan and dietician in the multi-disciplinary team. If there are vitamin insufficiencies, you will be advised accordingly.

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