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.
Extended (Distal) Roux-en-Y Gastric Bypass
(RYGBP-E)
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.
