Gastric Bypass Surgery

Roux en-Y gastric bypass surgery (RYGB) is still the gold standard operation against which other obesity operations are compared. First performed in the USA in 1967, gastric bypass has stood the test of time providing reliable, long-term weight loss with little long-term risk of malnutrition or complications. Globally it is the most common procedure with 200,000 gastric bypass operations performed in the US annually. First performed as an open operation it is now performed laparoscopically, reducing hospital stay to two or three days with a shorter time to return to normal activities.

How does RYGB work?

LRYGB has a physical and a hormonal effect. Physically it restricts food intake, portions sizes after the gastric bypass are much reduced with an early feeling of fullness. Over-eating causes abdominal discomfort and vomiting.

LRYGB also reduces a patient’s appetite. The mechanism by which this occurs is not fully understood.  After gastric surgery, including sleeve gastrectomy, most patients feel far less hungry, often forgetting to eat. Gastric bypass surgery,  affects the hormones that control blood sugar and consequently many diabetic patients become non-diabetic immediately after surgery.

Weight loss and Medical Benefits of Gastric Bypass Surgery

Research including many thousands of patients has shown that on average patients undergoing LRYGB will lose 65 to 70% of their excess weight. A lady  who is 5’6” tall and weighs nearly 20 stone (BMI 45 kg/m2) is 9 stone over her ideal weight. On average with a gastric bypass this patient will lose nearly seven stone and have a long-term weight of 13 stone.

In addition to weight loss there are proven health benefits. 90% of patients with Type 2 Diabetes Mellitus will go into remission from the disease. 70% of patients with raised blood cholesterol will be able to discontinue their medication. 70% of patients will have their high blood pressure cured, the remainder will be able to decrease their level of medication. 86% of patients with obstructive sleep apnoea will be cured by the surgery. Reflux of acid is usually cured by the surgery. Chronic back pain and osteo-arthritis  pain is usually improved.

The Operation

Gastric surgery requires a general anaesthetic. The operation lasts about two hours. Just before surgery antibiotics are given to you to reduce the risk of infection. The surgery is performed through six small incisions. each about a centimetre in length.

The first step of the operation is to make the Roux en-Y bypass from the small intestine. The small intestine is divided using a surgical stapler 0.75m to 1.25m from it’s beginning near the duodenum. Approximately 0.75 to 1.5 m from the place of division it is re-joined to the small intestine. This join is made using a combination of a surgical stapler and suturing. The next step is to make a small gastric pouch from the patient’s stomach. Surgical staplers are used to form a vertical pouch approximately 20 ml in volume, the size of an egg. The bypass is then joined to the pouch using a 1 cm diameter join called an anastomosis, again a combination of a surgical stapler and suturing is used. Local anaesthetic is injected around the skin incisions, which are closed with dissolvable stitches.

Most patients are in hospital for 48 hours and return to normal activities at about two weeks.

Risks and complications of Surgery

Although the surgery is more invasive than laparoscopic adjustable gastric band surgery, it is normally straightforward. In our hands complications are rare. Nevertheless LRYGB is major surgery and needs to be considered very carefully before going ahead. All the complications will be discussed at the initial consultation and a detailed patient information booklet will be provided.

Other considerations

Nutritional deficiency after surgery

Nutritional deficiencies can occur after surgery if patients don’t follow the recommended dietary advice. To avoid nutritional deficiencies patients need good dietetic follow up after surgery. Protein deficiency with loss of muscle can occur if patients don’t maintain a good protein intake. Vitamin deficiencies are uncommon as there is very little malabsorption of food with the roux en-Y gastric bypass. To avoid vitamin deficiencies we recommend patients take a good quality multi-vitamin each day. Iron deficiency anaemia and Vitamin B12 deficiency anaemia can occur after the surgery. We recommend an annual blood test to check for anaemia. Anaemia can be treated with iron supplements and sometimes vitamin B12 injections are needed. Although osteoporosis, “brittle bones” is not usually seen after bypass surgery we recommend that middle aged ladies take vitamin D and calcium supplements. Nutritional abnormalities can occur in patients who don’t eat properly with the bypass and rarely these can cause neurological illnesses.

Drug and alcohol absorption

With the exception of some slow release preparations, drugs absorption is not affected by the surgery. Nevertheless we advise patients not to rely on the oral contraceptive pill. Alcohol is absorbed more quickly after the surgery and patients need to bear this in mind when driving.

Infertility, contraception and pregnancy

Many morbidly obese ladies don’t ovulate regularly and may consider themselves infertile. Consequently many don’t use contraception. With weight loss many patients will start to ovulate and become fertile. For this reason female patients should consider what form of contraception they wish to use. The oral contraceptive pill may not be reliable after LRYGB and we recommend patients use an alternative form of contraception such as a depot injection, barrier methods or a coil. Your general practitioner should be able to advise you appropriately. Following LRYGB patients can safely have children but pregnancy should be avoided in the first year after surgery.

Guy Slater FRCS


01243 831655


07525 475682


0845 643 1400