Duodenal switch

# Overview
The Duodenal Switch (also known as Bilio-Pancreatic Diversion with Duodenal Switch or the DS) procedure is a weight loss surgery that alters the gastrointestinal tract with two approaches: a restrictive aspect and a malabsorptive aspect.
The restrictive portion of the surgery reduces the stomach along the greater curvature so that the volume is approximately one third to one fifth of the original capacity. The malabsorptive portion of the surgery reroutes a lengthy portion of the small intestine, creating two separate pathways and one common pathway. The shorter of the two pathways, the digestive loop, takes food from the stomach to the large intestine. The much longer pathway, the bilio-pancreatic loop, carries bile from the liver to the common path. The common path, or common channel, is a stretch of small intestine usually 75-150 centimeters long in which the contents of the digestive path mix with the bile from the bilio-pancreatic loop before emptying into the large intestine. The objective of this arrangement is to reduce the amount of time the body has to capture calories from food in the small intestine and to selectively limit the absorption of fat.

# Comparison to other surgeries

## Advantages
The primary advantage of the Duodenal Switch (DS) surgery is that its combination of moderate intake restriction with substantial calorie malabsorption results in a very high percentage of excess weight loss for obese individuals, with a very low risk of significant weight regain.
Because the pyloric valve between the stomach and small intestine is preserved, people who have undergone the DS do not experience the dumping syndrome common with people who've undergone the Roux-en-Y gastric bypass surgery.
The chance of developing anastamotic stricture (common with the RNY) is extremely low.
Much of the hunger hormone, Ghrelin, is removed with the greater curvature of the stomach.
Diet following the DS is more normal and better tolerated than with other surgeries.
Those who undergo the DS often find that comorbidities such as high blood pressure, diabetes mellitus type 2, and arthritis are significantly relieved in a short time after the surgery.
Type 2 Diabetes is "cured" - or put into remission - in 98% of patients having the DS. These benefits occur long before great losses in weight are seen.
Some surgeons do the "switch" or intestinal surgery on non-obese patients for the benefits of curing the diabetes.
Some surgeons are so confident in the benefits of the DS that they will accept super-morbidly obese patients, who are often turned down for other weight loss surgeries; however, anyone who qualifies with a body mass index (BMI) of 40 or a BMI of 35 with comorbidities qualifies for the more successful DS surgery.

## Disadvantages
The malabsorptive element of the DS requires that those who undergo the procedure take vitamin and mineral supplements above and beyond that of the normal population, as do patients having the RNY surgery. Commonly prescribed supplements include a daily prenatal vitamin and extra calcium citrate.
Because gallstones are a common complication of rapid weight loss following any type of weight loss surgery, some surgeons may remove the gall bladder as a preventative measure during the DS or the RNY.  Others prefer to prescribe medication to reduce the risk of post-operative gallstones.
Far fewer surgeons perform the DS compared to other weight loss surgeries because it is a more difficult one to learn compared to RNY and Lap Band procedures.

# Risks
All surgical procedures involve a degree of risk however this must be balanced against the significant risks associated with severe obesity. Some of the risks or complications that can attach to a bypass are:
Almost one-third of stomach bypass patients suffer from nutritional deficits due to non-oberservance of medical guidelines on the type and amount of food supplements to be taken after the operation.
Soon after the bypass operation patients may suffer from the following: staple failure causing leaks, infection, deep thrombo-phlebitis, ulcers and stomal stenosis.
Latterly other problems can arise that may necessitate corrective surgical procedures. The mortality and morbidity rates of these secondary operations are higher than those of the initial surgery.

# Qualifications
The National Institutes of Health state that if you meet the following guidelines, weight loss surgery may be an appropriate measure for permanent weight loss:
- BMI of 40 or over
- BMI of 35 or over with obesity-related illnesses such as:
Diabetes mellitus type 2
Coronary heart disease
Sleep apnea
Osteoarthritis
- Diabetes mellitus type 2
- Coronary heart disease
- Sleep apnea
- Osteoarthritis
- An understanding of the operation and lifestyle changes necessary following the surgery.

# Effectiveness
The following statistics are taken from Pacific Laproscopy and Duodenal Switch Information Zone.
- 3 months - 29 and 37%
- 6 months - 51 and 55%
- 24 months - 80 and 91%
- 97% diabetes resolved
- 96% high cholesterol resolved
- 90% sleep apnea resolved
- 85% hypertension resolved
- 60% asthma resolved
- 47% arthritis resolved