What types of gastric bypass operations are there? 

Roux-en-Y gastric bypass (RGB)

This type of operation is the most common gastric bypass procedure performed in the U.S. The main characteristics is that first a small stomach pouch is created by stapling part of the stomach together or by vertical banding. It isn't hard to understand that this limits how much food a person can eat. The next step is making a Y-shaped section of the small intestine which is being attached to the pouch to allow food to bypass the duodenum as well as the first portion of the jejunum. This part of operation causes reduced calorie and nutrient absorption.

Laparoscopic approach

This procedure can now be done with a laparoscope. Laparoscope is a thin telescope-like instrument for viewing inside the abdomen. This type of procedure involves using small incisions and generally has a shorter recovery time. Laparoscopic surgery also protects the patient's immune function while an open surgery can compromise the immune system and even promote the growth of any existing tumors.

Extensive gastric bypass

This is a far more complicated gastric bypass operation because the complete lower portion of the stomach is removed. The small pouch that remains is connected directly to the final segment of the small intestine. This means that both the duodenum and jejunum are being completely bypassed. Although a lot of people prefer this procedure because it successfully promotes weight loss, it is important to know that it is not as widely used because of the high risk of nutritional deficiencies.
 
Gastric bypass surgery is performed under a general anesthesia which means you inhale analgesics as a gas or receive them through an intravenous (IV) line so that you're asleep during the surgery.
During surgery, a tube is passed through thenose into the upper stomach pouch. Another tube may be placed in the bypassed stomach. This tube would come out of the side of the abdomen and is removed four to six weeks after the surgery. The hospital stay may last from three to five days.

How Well It Works

Most studies have shown that great majority of people who have gastric bypass surgery quickly begin to lose weight and continue to lose weight for up to 12 months. One study noted that people lost about one-third of their excess weight in 1 to 4 years. However, some of the lost weight may be regained. The laparoscopic approach showed similar results, with 69% to 82% of excess weight lost over 12 to 54 months.

Operation risks

Risks common to all surgeries for weight loss include:

• an infection in the incision - Infection of the incisions, or of the inside of the abdomen (peritonitis, abscess) may occur, due to release of bacteria from the bowel during the operation
• a leak from the stomach into the abdominal cavity or where the intestine is connected
• peritonitis
• a blood clot in the lung – condition called pulmonary embolism
• nutritional deficiency
• anemia or osteoporosis
• a risk of death has been associated with gastric bypass surgery and the risk varies depending on age, general health and other medical conditions.

It is important to note that fewer than 3 in 200 people die after this type of surgery.

After a Roux-en-Y gastric bypass

• Iron and vitamin B12 deficiency occurs in more than 30% of the cases
• These iron deficiencies can lead to a condition called anaemia
• The connection between the stomach and the intestines narrows 5% to 15% of the time which is leading to nausea and vomiting
• Ulcers develop 5% to 15% of the time
• The staples used in operation may pull loose which can lead to hernia
• The bypassed stomach may enlarge, resulting in hiccups and bloating
• Leakage of stomach contents into the abdomen which could be extremely dangerous because the acid can eat away other organs

That is why people who undergo this procedure are required to take nutritional supplements that usually prevent these deficiencies.

What to expect after surgery

This surgery usually involves a 4 to 6-day hospital stay. Most people can return to their normal activities within 3 to 5 weeks.

Dumping syndrome

Gastric bypass surgeries may cause dumping syndrome. This occurs when food moves too quickly through the stomach and intestines. It causes nausea, weakness, sweating, faintness, and possibly diarrhea soon after eating. These symptoms are made worse by eating highly refined, high-calorie foods (like sweets). In some cases you may become so weak that you have to lie down until the symptoms pass.