The American Society for Bariatric Surgery describes two basic approaches that
weight loss surgery takes to achieve change:
Restrictive procedures that decrease food intake.
Malabsorptive procedures that alter digestion, thus causing the food to
be poorly digested and incompletely absorbed so that it is eliminated in the
stool.
Vertical Banded Gastroplasty (VBG) is a purely restrictive procedure. In this
procedure the upper stomach near the esophagus is stapled vertically for about
2-1/2 inches (6 cm) to create a smaller stomach pouch. The outlet from the pouch
is restricted by a band or ring that slows the emptying of the food and thus
creates the feeling of fullness.
Advantages
The primary advantage of this restrictive procedure is that a reduced amount
of well-chewed food enters and passes through the digestive tract in the usual
order. That allows the nutrients and vitamins (as well as the calories) to
be fully absorbed into the body.
After 10 years, studies show that patients can maintain 50% of targeted
excess weight loss.
Risks
Postoperatively, stapling of the stomach carries with it the risk of staple-line
disruption that can result in leakage and/or serious infection. This may require
prolonged hospitalization with antibiotic treatment and/or additional operations.
Staple-line disruption may also, in the long-term, lead to weight gain.
For these reasons, some surgeons divide the staple-line wall of the pouch
from the rest of the stomach to reduce the risk of long-term staple-line disruption.
The band or ring applied may lead to complications of obstruction or perforation,
requiring surgical intervention.
Characteristically, these procedures, while creating a sense of fullness,
do not provide the necessary feeling of satisfaction that one has had "enough"
to eat.
Because restrictive procedures rely solely on a small stomach pouch to reduce
food intake, there is the risk of the pouch stretching or of the restricting
band or ring at the pouch outlet breaking or migrating, thus allowing patients
to eat too much.
Around 40% of patients undergoing these procedures have lost less than half
their excess body weight.
As is the case with all weight loss surgeries, readmission to a hospital
may be required for fluid replacement or nutritional support if there is excessive
vomiting and adequate food intake cannot be maintained.
While these operations also reduce the size of the stomach, the stomach pouch
created is much larger than with other procedures. The goal is to restrict the
amount of food consumed and alter the normal digestive process, but to a much
greater degree. The anatomy of the small intestine is changed to divert the
bile and pancreatic juices so they meet the ingested food closer to the middle
or the end of the small intestine.With the three approaches discussed below,
absorption of nutrients and calories is also reduced, but to a much greater
degree than with previously discussed procedures. Each of the three differs
in how and when the digestive juices (i.e., bile) come into contact with the
food.
Since food bypasses the duodenum, all the risk considerations discussed in
the gastric bypass section regarding the malabsorption of some minerals and
vitamins also apply to these techniques, only to a greater degree.
Biliopancreatic Diversion (BPD)
BPD removes approximately 3/4 of the stomach to produce both restriction of
food intake and reduction of acid output. Leaving enough upper stomach is important
to maintain proper nutrition. The small intestine is then divided with one end
attached to the stomach pouch to create what is called an "alimentary limb."
All the food moves through this segment, however, not much is absorbed. The
bile and pancreatic juices move through the "biliopancreatic limb,"
which is connected to the side of the intestine close to the end. This supplies
digestive juices in the section of the intestine now called the "common
limb." The surgeon is able to vary the length of the common limb to regulate
the amount of absorption of protein, fat and fat-soluble vitamins.
RYGBP-E is an alternative means of achieving malabsorption by creating a stapled
or divided small gastric pouch, leaving the remainder of stomach in place. A
long limb of the small intestine is attached to the stomach to divert the bile
and pancreatic juices. This procedure carries with it fewer operative risks
by avoiding removal of the lower 3/4 of the stomach. Gastric pouch size and
the length of the bypassed intestine determine the risks for ulcers, malnutrition
and other effects.
Biliopancreatic Diversion with "Duodenal Switch"
This procedure is a variation of BPD in which stomach removal is restricted
to the outer margin, leaving a sleeve of stomach with the pylorus and the beginning
of the duodenum at its end. The duodenum, the first portion of the small intestine,
is divided so that pancreatic and bile drainage is bypassed. The near end of
the "alimentary limb" is then attached to the beginning of the duodenum,
while the "common limb" is created in the same way as described above.
Advantages
These operations often result in a high degree of patient satisfaction because
patients are able to eat larger meals than with a purely restrictive or standard
Roux-en-Y gastric bypass procedure.
These procedures can produce the greatest excess weight loss because they
provide the highest levels of malabsorption.
In one study of 125 patients, excess weight loss of 74% at one year, 78%
at two years, 81% at three years, 84% at four years, and 91% at five years
was achieved.
Long-term maintenance of excess body weight loss can be successful if the
patient adapts and adheres to a straightforward dietary, supplement, exercise
and behavioral regimen.
Risks
For all malabsorption procedures there is a period of intestinal adaptation
when bowel movements can be very liquid and frequent.
This condition may lessen over time, but may be a permanent lifelong occurrence.
Abdominal bloating and malodorous stool or gas may occur.
Close lifelong monitoring for protein malnutrition, anemia and bone disease
is recommended. As well, lifelong vitamin supplementing is required. It has
been generally observed that if eating and vitamin supplement instructions
are not rigorously followed, at least 25% of patients will develop problems
that require treatment.
Changes to the intestinal structure can result in the increased risk of
gallstone formation and the need for removal of the gallbladder.
Re-routing of bile, pancreatic and other digestive juices beyond the stomach
can cause intestinal irritation and ulcers.
In recent years, better clinical understanding of procedures combining restrictive
and malabsorptive approaches has increased the choices of effective weight loss
surgery for thousands of patients. By adding malabsorption, food is delayed
in mixing with bile and pancreatic juices that aid in the absorption of nutrients.
The result is an early sense of fullness, combined with a sense of satisfaction
that reduces the desire to eat.
According to the American Society for Bariatric Surgery and the National Institutes
of Health, Roux-en-Y gastric bypass is the current gold standard procedure for
weight loss surgery. It is one of the most frequently performed weight loss
procedures in the United States. In this procedure, stapling creates a small
(15 to 20cc) stomach pouch. The remainder of the stomach is not removed, but
is completely stapled shut and divided from the stomach pouch. The outlet from
this newly formed pouch empties directly into the lower portion of the jejunum,
thus bypassing calorie absorption. This is done by dividing the small intestine
just beyond the duodenum for the purpose of bringing it up and constructing
a connection with the newly formed stomach pouch. The other end is connected
into the side of the Roux limb of the intestine creating the "Y" shape
that gives the technique its name. The length of either segment of the intestine
can be increased to produce lower or higher levels of malabsorption.
Advantages
The average excess weight loss after the Roux-en-Y procedure is generally
higher in a compliant patient than with purely restrictive procedures.
One year after surgery, weight loss can average 77% of excess body weight.
Studies show that after 10 to 14 years, 50-60% of excess body weight loss
has been maintained by some patients.
A 2000 study of 500 patients showed that 96% of certain associated health
conditions studied (back pain, sleep apnea, high blood pressure, diabetes
and depression) were improved or resolved.
Risks
Because the duodenum is bypassed, poor absorption of iron and calcium can
result in the lowering of total body iron and a predisposition to iron deficiency
anemia. This is a particular concern for patients who experience chronic blood
loss during excessive menstrual flow or bleeding hemorrhoids. Women, already
at risk for osteoporosis that can occur after menopause, should be aware of
the potential for heightened bone calcium loss.
Bypassing the duodenum has caused metabolic bone disease in some patients,
resulting in bone pain, loss of height, humped back and fractures of the ribs
and hip bones. All of the deficiencies mentioned above, however, can be managed
through proper diet and vitamin supplements.
A chronic anemia due to Vitamin B12 deficiency may occur. The problem can
usually be managed with Vitamin B12 pills or injections.
A condition known as "dumping syndrome " can occur as the result
of rapid emptying of stomach contents into the small intestine. This is sometimes
triggered when too much sugar or large amounts of food are consumed. While
generally not considered to be a serious risk to your health, the results
can be extremely unpleasant and can include nausea, weakness, sweating, faintness
and, on occasion, diarrhea after eating. Some patients are unable to eat any
form of sweets after surgery.
In some cases, the effectiveness of the procedure may be reduced if the
stomach pouch is stretched and/or if it is initially left larger than 15-30cc.
The bypassed portion of the stomach, duodenum and segments of the small
intestine cannot be easily visualized using X-ray or endoscopy if problems
such as ulcers, bleeding or malignancy should occur.
For the last decade, laparoscopic procedures have been used in a variety of
general surgeries. Many people mistakenly believe that these techniques are
still "experimental." In fact, laparoscopy has become the predominant
technique in some areas of surgery and has been used for weight loss surgery
for several years. Although few bariatric surgeons perform laparoscopic weight
loss surgeries, more are offering patients this less invasive surgical option
whenever possible.
When a laparoscopic operation is performed, a small video camera is inserted
into the abdomen. The surgeon views the procedure on a separate video monitor.
Most laparoscopic surgeons believe this gives them better visualization and
access to key anatomical structures.
The camera and surgical instruments are inserted through small incisions made
in the abdominal wall. This approach is considered less invasive because it
replaces the need for one long incision to open the abdomen. A recent study
shows that patients having had laparoscopic weight loss surgery experience less
pain after surgery resulting in easier breathing and lung function and higher
overall oxygen levels. Other realized benefits with laparoscopy have been fewer
wound complications such as infection or hernia, and patients returning more
quickly to pre-surgical levels of activity.
Laparoscopic procedures for weight loss surgery employ the same principles
as their "open" counterparts and produce similar excess weight loss.
Not all patients are candidates for this approach, just as all bariatric surgeons
are not trained in the advanced techniques required to perform this less invasive
method. The American Society for Bariatric Surgery recommends that laparoscopic
weight loss surgery should only be performed by surgeons who are experienced
in both laparoscopic and open bariatric procedures.