Intestinal bypass

In the human digestive system, the stomach is responsible for mechanical and chemical digestions. The small intestine is involved in both the absorption and digestion of nutrients, whereas the large intestine is responsible for the elimination of wastes (defecation). The small intestine consists of 3 parts: duodenum, jejunum and ileum. The duodenum is the first part of the small intestine and is connected to the stomach via the pyloric valve. The jejunum is the second and middle part of the small intestine. The ileum is the last part of the small intestine and is connected to the cecum, a part of the large intestine, via the ileocecal valve. == Types of intestinal bypass ==

Procedures of intestinal bypass surgery The intestinal bypass surgery, as the name suggests, anastomoses 14 inches of the proximal duodenum, the part of the small intestine closest to the stomach, to the 4 inches of the distal ileum, the part of the small intestine closest to large intestines. As a corollary, the absorption of nutrients is greatly reduced, and thus lead to apparent weight reduction. There are four variations of intestinal bypass. They are jejunocolic bypass, end-to-side jejunoileal bypass, end-to-end jejunoileal bypass, and biliopancreatic diversion, respectively. == Mechanisms of weight reduction ==

This surgery acts in the following ways to help patients reduce their body weight: Induction of malabsorption Induction of malabsorption is the most prominent effect of the surgery. The small intestines are responsible for most of the absorption of nutrients. By bypassing a considerable length of the small intestines, this type of surgery greatly reduces the absorption capacity of the digestive system. Malabsorption is especially prominent in biliopancreatic diversion. Not only does it reduce the length of the small intestine for absorption, but it also drains the bile and digestive enzymes only to the distal ileum. Bile is essential for fat absorption, while digestive enzymes facilitate the intake of proteins. Draining them to only the distal ileum further reduces the efficiency of intestinal absorption, hence achieving the goal of weight reduction. Conditioning of appetite If the patients take excessive food after the surgery, they will experience abdominal discomforts such as steatorrhea and abdominal pain, as patients' digestive system capacity has been reduced drastically. == Selection Criteria ==

Intestinal bypass, in spite of its highly effectiveness in weight reduction, is a risky and irreversible. Thus, it requires rigorous assessment and selection before the surgery is carried out. The following are the normal selection criteria: • Overweight for more than 100 lbs. • Readiness to accept the side effects and hence all the follow-up procedures. • Evidence of failure in all previous attempts in weight reduction. • Stable mental health status. • Psychiatric evaluation showing the obese state. • An absence of all types of endocrinopathies that are correctable. This surgery serves as the LAST approach to lose weight when all other weight-losing methods have failed and at the same time, morbid obesity remains a life-threatening problem. It is crucial for patients to understand all the pros and cons of this surgery, despite the weight loss they aimed for. == Health impacts ==

Intestinal bypass surgery can lead to loss of weight effectively, but it can also lead to various complications that should not be neglected. About half of the patients who received this surgery need rehospitalization to manage the complications. Physical weakness Fatigue is common after the surgery due to the malabsorption of nutrients. Complications • Kidney stone is also an associated risk of the intestinal bypass surgery. This is mainly due to enteric hyperoxaluria. Increased absorption of oxalate in colons rises the risk of the formation of kidney stones. Dysfunctions in GI tracts Flatulence is observed even after years of surgery. == Nutritional deficiencies and solutions ==

Nutritional deficiencies are often seen in patients after the surgery due to malabsorption. They include: Loss of appetite Anorexia is considered to be a normal response found after the first few weeks of the surgery but after four to six weeks, most patients gain back their initial appetite before receiving the surgery. Lack of vitamins Low serum levels of Vitamin B12, Vitamin A, Vitamin D, Vitamin E, and Vitamin K are common nutritional deficiencies after the surgery. 1000 mg of Vitamin B12 is recommended monthly, and supplements of vitamins and minerals are also recommended for the first half to full year after the surgery until the rapid weight loss period has passed. Damages to organs Hepatic damage results from the inadequacy in nutritional supply and steatosis, where it remains as the most serious, and possibly lethal, side effect. Patients may show symptoms like nausea and emesis. Intake of alcohol is intolerable as it increases the tendency for the liver to become impaired. Incidents of death due to liver failure have also been reported. By applying amino acid replacement orally right after the surgery, prevention of these liver problems may be achieved. ==Alternatives to intestinal bypass==

Alternative surgical treatments Due to the aforementioned complications, instead of performing the intestinal bypass surgery, gastric bypass surgery is a more commonly used bariatric surgery nowadays. Intestinal bypass surgery induces malabsorption by anastomosing proximal and distal small intestine. Yet, the small intestine has an important role in performing a wide range of important physiological and metabolic functions, such as the metabolism of lipids. Stomach, on the contrary, has a less significant role in the physiological and metabolic functions. The most prominent physiological function of the stomach is digestion, but the small intestine is also capable of digestion. Thus, gastric bypass surgery does less harm to the overall metabolism of nutrients. Gastric bypass leads to weight loss by controlling the appetite of the patients, instead of inducing malabsorption. As a result, the intestinal bypass is now replaced by an alternative of gastric bypass. Anti-obesity medications Anti-obesity medications is also a possible solution. Examples of such medications include the Orlistat, With effective medications, the obese can better control their weight without the need of undergoing a relatively high-risk surgery. == See also ==