Treatment is by surgical removal of the
tumour, but thecancer has often spread
to the liver by the time it is detected,
making the outlook poor.
gallbladder, disorders ofThe princi-
palgallbladderdisorder is gallstones,
which are common and often symptom-
less. Attempts by the gallbladder to
expel the stones can cause biliary colic.
If a gallstone becomes stuck in the gall-
bladder outlet, acute cholecystitismay
develop. Occasionally, this leads to a
painful condition called empyemaof the
gallbladder. If a gallbladder is empty
when a stone obstructs its outlet, it may
fill with mucus, resulting in a mucocele.
Gallbladder canceris rare.
galliumA metallic element whose
radioactive form is used in radionuclide
scanningto detect areas of inflamma-
tion such as those that occur in cancers,
abscesses, osteomyelitis, and sarcoidosis.
gallstonesLumps of solid matter found
in the gallbladder, or in the bile ducts.
Gallstones are composed mainly of
cholesteroland bile pigments from the
breakdown of red blood cells. They
developwhen there is a disturbance in
the chemical composition of bile.
Gallstones are rare in childhood and
become increasingly common with age.
Women are affected more than men.
Risk factors include a high-fat diet and
being overweight.
Most gallstones cause no symptoms.
When symptoms do occur, they often
begin when a stonegets stuck in the
duct leading from the gallbladder, caus-
ing biliary colicand nausea.Gallstones
may cause indigestion and flatulence.
Possible complications are cholecystitis
and bile duct obstruction.
Diagnosis is by ultrasound scanning,
X-ray oral cholecystography, or cholan-
giography. Stones that are not causing
symptoms are usually left alone. In
other cases, the gallbladder and stones
may be removed by cholecystectomy.
Ultrasonic shock waves (see lithotripsy)
are sometimes used to shatter stones;
the fragments pass into the bowel and
cause no further problems. Drugs such
as chenodeoxycholic acidor ursodeoxy-
cholic acidcan dissolve some stones if
given over a period of months.gambling, pathologicalChronic in-
ability to resist impulses to gamble,
resulting in personal or social problems.
gameteA sex cell, which is either the
spermof the male or the ovum(egg
cell) of the female.
gamete intrafallopian transfer
(GIFT)A technique for assisting con-
ception(see infertility), which can only
be used if a woman has normal fallopian
tubes. In GIFT, eggs are removed from
an ovaryduring laparoscopyand mixed
with sperm in the laboratory before
both are introduced into a fallopian
tube. A fertilized egg may then become
implanted in the uterus.
gamma-globulinA substance pre-
pared from human blood that contains
antibodiesagainst most common infec-
tions. (See immunoglobulin injections.)
gamolenic acid An essential fatty acid
found in evening primrose oil and
starflower oil (borage oil). Gamolenic
acid may be prescribed for breast ten-
derness, premenstrual syndrome, and
eczema. Very large doses may cause
abdominal pain and loose stools.
ganciclovir An antiviral drugthat is
used to treat serious cytomegalovirus
infection in people with an impaired or
suppressed immune system as a result
of AIDS or following organ transplan-
tation. Side effects include nausea,
diarrhoea, abdominal pain, weakness,
and bone marrow suppression.
ganglionA group of nervecells that have
a common function; for example, the
basal gangliain the brain are concerned
with the control of muscular movements.
The term is also used to describe a
fluid-filled swelling associated with the
sheath of a tendon.
gangreneDeath of tissue, usually as a
result of loss of blood supply. Gangrene
may affect a small area of skin or a sub-
stantial portion of a limb. Pain is felt in
the dying tissues, but once dead they
become numb. The affected tissue turns
black. There are two types of gangrene:
dry and wet. In dry gangrene, there is
usually no infection, and the tissue
dies because it has no blood supply.
Dry gangrene does not spread, and it
may be caused by arteriosclerosis, dia-
betes mellitus, thrombosis, frostbite, orGALLBLADDER, DISORDERS OF GANGRENEG