BILATERAL
B
(sugar) in the liver and also increases
the uptake of glucose by the body’s
cells. (See also
antidiabetic drugs.)
bilateral
A term that means affecting both sides
of the body or affecting both organs if
they are paired (for example, both ears
in bilateral deafness).
bile
A greenish-brown alkaline liquid that is
secreted by the
liver.
Bile carries away
waste products formed in the liver and
also helps to break down fats in the
small intestine for digestion.
The waste products in bile include
the pigments
bilirubin
and biliverdin,
which give bile its greenish-brown col-
our;
bile
salts,
which
aid
in
the
breakdown and absorption of fats; and
cholesterol.
Bile passes out of the liver
through the
bile ducts
and is then con-
centrated and stored in the gallbladder.
After a meal, bile is expelled and enters
the duodenum (the first section of the
small intestine) via the common bile
duct. Most of the bile salts are later
reabsorbed into the bloodstream to be
recycled by the liver into bile. Bile pig-
ments are excreted in the faeces. (See
also
biliary system; colestyramine.)
bile duct
Any of the ducts through which
bile
is
carried from the
liver
to the gallbladder
and then on to the duodenum (the first
section of the small intestine).
The bile duct system forms a network
of tubular
canals.
Canaliculi
(small
canals) surround the liver cells and col-
lect the bile. The canaliculi join together
to form ducts of increasing size. The
ducts emerge from the liver as the two
hepatic ducts, which join within or just
outside the liver to form the common
hepatic duct. The cystic duct branches
off to the gallbladder; from this point
the common hepatic duct becomes the
common bile duct and leads into the
duodenum. (See also
biliary system.)
bile duct cancer
See
cholangiocarcinoma.
bile duct obstruction
A blockage or constriction of a bile duct
(see
biliary system).
Obstruction of a bile
duct results in the accumulation of bile
in the liver
(cholestasis)
and
jaundice
(yellowing of the skin and the whites of
the eyes) due to a buildup of
bilirubin
(bile pigment) in the blood. Prolonged
obstruction of the bile duct can lead to
secondary
biliary cirrhosis,
which is a
serious form of liver disease.
CAUSES
The most common cause of bile duct
obstruction is
gallstones.
Other causes
include a tumour affecting the pancreas
(see
pancreas, cancer of
) and cancer that
has spread from elsewhere in the body
Cholangiocarcinoma
(cancer of the bile
ducts) is a rare cause of a blockage. Bile
duct obstruction is known to be a rare
side effect of certain drugs. It may also
be caused by
cholangitis
(inflammation
of the bile ducts), trauma (such as
injury during surgery), and, rarely, by
flukes
or worms.
SYMPTOMS
Bile duct obstruction causes “obstruc-
tive” jaundice, which is characterized
by pale-coloured faeces, dark urine, and
a yellow skin colour. There may also be
itching. Other symptoms of bile duct
obstruction depend on the cause of the
blockage; for example, there may be
abdominal pain
(with gallstones)
or
weight loss (with cancer).
TREATMENT
Treatment depends on the cause, but
surgery is sometimes necessary Gall-
stones may be removed by means of
ERCP
(an X-ray procedure that uses a
viewing tube called an endoscope with
instruments attached to it).
bilharzia
Another name for the tropical parasitic
disease
schistosomiasis
.
biliary atresia
A rare
congenital
disorder in which
some or all of the
bile ducts
fail to
develop or develop abnormally. As a
result,
bile
is unable to drain from the
liver (see
cholestasis).
Unless the atresia
can be treated, secondary
biliary cirrhosis
(a serious liver disorder) will develop
and may prove fatal. Symptoms include
jaundice,
usually beginning a week after
birth, and the passing of dark urine and
pale faeces. Treatment is by surgery to
bypass the ducts. If this fails, or if
the jaundice recurs, a
liver transplant
is required.
biliary cirrhosis
An uncommon form of liver
cirrhosis
that results from problems with the bile
ducts. There are two types of biliary cir-
rhosis. One is an
autoimmune disorder
and is known as primary biliary cirrho-
sis. Secondary biliary cirrhosis occurs as
a result of a longstanding blockage. In
both types of the condition, liver func-
tion
is
impaired
due
to
cholestasis
(accumulation of bile in the liver).
Primary biliary cirrhosis principally
affects middle-aged women and seems
to be linked with a malfunction of the
immune system.
In this disorder, the bile
ducts within the liver become inflamed
and are destroyed. Symptoms include
itching,
jaundice
(a yellowish discolor-
ation of the skin and the whites of the
eyes), an enlarged liver, and sometimes
abdominal pain, fatty diarrhoea, and
xanthomatosis
(deposits of fatty material
under the skin).
Osteoporosis
may also
develop. Symptoms of liver cirrhosis
and
liver failure
may occur after a few
years. Drugs can be used to minimize
complications and to relieve symptoms
such as itching, but a
liver transplant
is
the only cure.
Secondary
biliary
cirrhosis
results
from prolonged
bile duct obstruction
or
biliary atresia
(abnormal
bile
ducts).
Symptoms and signs include abdominal
pain and tenderness, liver enlargement,
fevers and chills, and sometimes blood
abnormalities. Treatment is the same as
for bile duct obstruction.
biliary colic
A severe pain in the upper right quad-
rant of the abdomen that is usually
caused by the gallbladder’s attempts to
expel
gallstones
or by the movement of
a stone in the
bile ducts.
The pain may
be felt in the right shoulder (see
referred
pain
) or may penetrate to the centre of
the back. Episodes of biliary colic often
last for several hours and may recur,
particularly after meals.
Injections of an
analgesic drug
and
anti-
spasmodic drug
may be given to relieve
the colic. Tests such as
cholecystography
or
ultrasound scanning
can confirm the
presence of gallstones, in which case
cholecystectomy
(surgical removal of the
gallbladder) may be performed.
biliary system
The organs and ducts in which
bile
is
formed, concentrated, and carried from
the
liver
to the duodenum (the first part
of the small intestine). Bile is secreted
by liver cells and collected by a network
of
bile ducts
that carry the bile out of the
liver via the hepatic duct. The cystic
duct branches off the hepatic duct and
leads to the gallbladder, where the bile
is concentrated and stored. Beyond this
98
previous page 97 BMA A Z Family Medical Encyclopedia   2004 read online next page 99 BMA A Z Family Medical Encyclopedia   2004 read online Home Toggle text on/off