Encyclopedia of Health and Medicine

286 Lifestyle Variables: Smoking and Obesity
through several small incisions called ports and
generally require less time in the operating room.
The stay in the hospital after bariatric surgery
varies from a day for laparoscopic banding operations
to five days or longer for open gastric bypass
or biliopancreatic diversion operations. Full recovery
and return to normal activities can take several
months, though many people are able to
return to most routine activities and to work in
four to six weeks.
Jejunoileal bypass Jejunoileal bypass is a malabsorption
operation. The first weight-reduction
operation surgeons performed, the jejunoileal
bypass joins the first part of the SMALL INTESTINE’s
second segment, the JEJUNUM, to the last part of
the small intestine’s third segment, the ILEUM. This
bypasses the stretch of small intestine where most
nutrient absorption takes place, rerouting food relatively
undigested on a direct path from the STOM-
ACH to the end of the small intestine and into the
COLON. Though successful in generating significant
weight loss jejunoileal bypass has numerous
unpleasant side effects, including chronic and
sometimes persistent or severe DIARRHEA, MALNU-
TRITION, electrolyte imbalance, and small bowel
obstruction (ILEUS). Because of the high rate of
complications with jejunoileal bypass and the current
availability of other weight loss operations,
surgeons in the United States seldom perform
jejunoileal bypass today.
Biliopancreatic diversion Biliopancreatic diversion
combines restriction and malabsorption.
Developed as an improvement over jejunoileal
bypass, the operation involves removing a portion
of the stomach to reduce the volume of food it can
hold as well as bypasses the central segment of the
small intestine to curtail absorption during digestion.
The surgery may be open or laparoscopic
(minimally invasive). The first segment of the
small intestine, the DUODENUM, connects the stomach
to the small intestine and also serves as the
conduit through which the PANCREAS channels
DIGESTIVE ENZYMES and the GALLBLADDER empties
BILE.
In straight biliopancreatic diversion, the surgeon
removes the lower two thirds of the stomach
and connects the remaining third directly to the
ileum, the end portion of the small intestine near
its junction with the colon. The stomach becomes
a very small pouch, restricting the amount of food
that can enter the gastrointestinal tract. The digestive
process bypasses most of the small intestine,
limiting absorption.
A variation of this operation is biliopancreatic
diversion with duodenal switch. In this operation
the surgeon divides the stomach about in half
lengthwise, creating a pouch between the ESOPHA-
GUS and the duodenum. The surgeon then divides
the duodenum in half lengthwise and reconstructs
it into two narrow, tubelike structures. One of
these structures drains digestive enzymes from the
pancreas and bile from the gallbladder into the
gastrointestinal tract. The surgeon joins the other
to the end portion of the ileum near the colon.
Biliopancreatic diversion with duodenal switch
allows better absorption in the remaining segment
of small intestine of NUTRIENTS such as protein,
vitamins, calcium, iron, and fat.
Gastric bypass Gastric bypass operations
severely restrict food consumption by reducing the
size of the stomach to a small pouch that can hold
about 0.5 ounce (15 milliliters); the stomach normally
holds about 50 ounces (1.5 liters). The most
common and successful gastric bypass operation is
the Roux-en-Y gastric bypass, a complex operation
in which the surgeon divides the stomach to form
two segments and reroutes the small intestine.
Both segments of the stomach remain functional.
The upper segment is a small gastric pouch with a
capacity of 0.5 to 1 ounce. The surgeon joins the
jejunum to the bottom of the pouch, bypassing
the primary absorptive segment of the small intestine.
The lower segment of the stomach retains
the duodenum, which the surgeon restructures to
join the jejunum near the ileum. The duodenum
feeds digestive enzymes and DIGESTIVE HORMONES
into the jejunum to aid in the absorption of nutrients.
Gastric banding Like gastric bypass operations,
gastric banding operations reduce the stomach to
a small pouch that can hold about 0.5 ounce and
narrow the outlet at the base of the stomach to
slow the passage of food from the stomach to the
small intestine. Gastric banding significantly limits
the volume of food the person can consume;
exceeding the limit causes VOMITING. Surgeons