Gastric bypass surgery

Gastric bypass operations are more extensive than gastric lapbanding operations. There are several varieties of bypass, but all involve the creation of a small stomach pouch to restrict food intake and construction of bypasses of the duodenum and other segments of the small intestine to cause malabsorption (decreased ability to absorb calories and nutrients from food). Thus unlike lapbanding which is a restrictive procedure only, gastric bypass is both restrictive and malabsorptive.

Types of gastric bypass operations

Though there are a number of variations, two of the most commonly performed bypass procedures are the Roux-en-Y gastric bypass and the Biliopancreatic Diversion (BPD). These - and their variations - can be performed as either open or closed (keyhole) procedures.

Roux-en-Y gastric bypass (RGB)

This operation is the most common gastric bypass procedure performed. First, a small stomach pouch is created by stapling part of the stomach together or by vertical banding. This limits how much food you can eat. Next, a Y-shaped section of the small intestine is attached to the pouch to allow food to bypass the duodenum as well as the first portion of the jejunum. This causes reduced calorie and nutrient absorption.

Biliopancreatic diversion (BPD)

In this more complicated version, portions of the stomach are removed and the small pouch that remains is connected directly to the final segment of the small intestine. This means that most of the small intestine (duodenum and jejunum) is bypassed, resulting in substantial reductions in calorie and nutrient absorption.

How long does a gastric-bypass take?

This depends on the experience of the surgeon and whether it is being done as an open or closed (keyhole) procedure. Open gastric bypass operations usually take 90-120 minutes, but laparoscopic bypasses may take up to twice as long to perform.

How long will I be in hospital?

For open operations, most patients are discharged on the third or fourth post-operative day. Patients who have the laparoscopic procedure can go home on the second or third post-operative day.

What are the risks of gastric bypass?

As with any surgery, there are operative and long-term complications and risks associated with gastric bypass, including:

• Bleeding (haemorrhage)
• Complications due to anaesthesia and medications
• Deep vein thrombosis
• Dehiscence (wound breakdown)
• Infections
• Leaks from staple line breakdown
• Marginal ulcers
• Pulmonary emboli (blood clots on the lung)
• Injury to the spleen

However, in experienced hands the risks of the procedure nowadays are very small. Most published reports show that the overall mortality rate for gastric bypass surgery is less than 1%.

It’s also important to note that not only does bypass result in reduced absorption of calories, it may also reduce absorption of important vitamins and minerals such as iron, vitamin B-12 and calcium. Deficiencies in these nutrients can lead to many problems. Iron deficiency causes anemia and weakness and deficiencies in calcium can cause osteoporosis. Lack of daily B-12 can lead to neurological problems. This is why patients undergoing gastric bypass are recommended to take a daily vitamin and mineral supplement.

"Dumping syndrome," in which the consumption of sugar causes abdominal cramping and diarrhoea, can also occur. Some people will also regain some weight in subsequent years.

A word of caution

Although there is no doubt that surgery can be both life-transforming and life-saving, the decision to go ahead with surgery is a serious one. Any general anaesthetic involves a measure of risk and individuals with serious degrees of obesity are at greater risk than their non-obese counterparts. You should ensure that the surgeon you choose is experienced and that the full panoply of specialist advice is available at the hospital you choose.

The choice of surgeon is crucial. This is not a procedure for the general surgeon. It should only be carried out by those who are specially trained in the surgery of the upper abdomen (upper GI surgeons).

What are the benefits of gastric bypass?

For the seriously obese, the benefits of the gastric bypass procedure very much outweigh the risks. In general:

• 75% of patients are expected to lose 75 to 80% of their excess body weight, most of which is lost in the first two years following surgery
• There are major improvements in risk factors for heart disease and cancer
• Around 70-80% of patients with hypertension will be off medication and cholesterol levels will fall
• Most type II diabetics will be cured
• There will be major improvements in a whole range of weight-associated conditions, including sleep apnoea, asthma, joint pain, arthritis, reflux, fatigue, shortness of breath
• Patients report less depression, improved self- esteem and confidence and an overall increased sense of well-being.

The need for long-term follow up

A final note of caution is to remember that surgery is not a cure for obesity. It is not a magic bullet and will not guarantee results without complete dedication by yourself and by your physician. If you are going to be successful you will have to continue to work on the behaviours which are important for anyone attempting to lose weight, including physical activity, reducing portion sizes, avoiding energy-dense foods etc. For this reason, you should ensure the hospital of your choice has available a structured, long-term behavioural and lifestyle programme, with nutritional support, which you should join immediately after surgery.

Additional information