What are the options?
There are essentially two mechanisms for surgery to achieve weight loss. These are defined as "restrictive" or "malabsorptive". Some operations include a combination of the two mechanisms.
A tiny pouch is created at the top of the stomach with a small outlet back into the rest of the stomach. Patients get full quickly and this is referred to as "early satiety". They therefore stop eating or will vomit. Operations that fit into this category include the horizontal and vertical gastroplasty,
sleeve gastrectomy and the adjustable band. The adjustable band is an inflatable band placed around the top of the stomach with keyhole surgery. Patients are generally able to go home the next day and begin band adjustments in six weeks. It has the advantage that the band diameter can be adjusted to achieve the desired outlet size from the pouch into the stomach. Patients do not develop nutritional deficiencies in the long term and the operations are technically easier to perform than those involving a bypass component. It is completely reversible. Weight loss however is slower and more frequent followup and adjustments are required. Patients can hope to lose approximately 50% of their excess weight at 3 years. Some surgeons believe that the weight loss is as good as the gastric bypass (see later). Many don't. The adjustable band can be easily removed. Major complications can occur related to this type of surgery but are uncommon. Reoperation for slipped band, leaking band, port site infection or band erosion however can be relatively high, greater than 20% in some series. Long term success of this procedure is
One of the first operations for obesity was the small bowel bypass (generally referred to as the jejunal ileal bypass). This procedure caused food to bypass most of the small bowel reaching the large bowel largely undigested. Weight loss was spectacular but nutritional deficiencies were severe. Patients developed kidney stones, low proteins and vitamins in the blood and some went on to cirrhosis and liver failure. Many of these bypasses were reversed and predictably
then patients put on all the weight they lost.
Combined Restrictive and Malabsorptive Operations
Operations such as the gastric bypass and the biliopancreatic bypass have been developed as a result of the lessons learned from the operations above. These combine both a restrictive component with a bypass (that is less radical than the jejunal-ileal bypass). These hybrid operations are thought to combine the best features of the restrictive and malabsorptive operations. The biliopancreatic bypass is not commonly performed in New Zealand. Because it creates a longer bypassed segment of bowel than the gastric bypass, nutritional deficiencies are thought to be more common and closer followup is required.
The gastric bypass operation is the most common operation performed for the morbidly obese in the United States where approximately 100,000 weight loss operations have been performed in the last year. It is sometimes referred to as the "Gold Standard" for obesity surgery. It has been shown to be superior to purely restrictive operations such as the vertical or horizontal gastroplasty
or adjustable band. It has stood the test of time for over 30 years and various modifications over the years have improved its results.
It involves the creation of a tiny pouch at the top of the stomach (as in the gastroplasty) however the outlet is directly joined into small bowel further down from the stomach. This creates a lesser degree of malabsorption but also encourages patients to eat sensibly. This operation can be performed through a traditional incision or via keyhole surgery.
If patients eat high calorie foods such as sweets, chocolates or fatty food they may feel nauseated, lightheaded and uncomfortable. Abdominal cramping and a desire to move the bowels may also occur. This is known as "dumping" and thereby acts as a deterrent from eating these foods. Patients can become hypoglycaemic
(low blood sugar) as well with similar symptoms to dumping.