ASCITES
A
LIFE CYCLE OF THE ASCARIS WORM
The person
becomes infested
by swallowing the
eggs, which
hatch into larvae
in the intestine.
The larvae travel
in the blood
through the wall
of the intestine to
the lungs, up the
windpipe, and
are swallowed
backinto the
small intestine.
There they
become adult
worms.
CAUSES
The parasite that causes ascariasis is a
pale, cylindrical, tapered roundworm,
which reaches between 15 and 3 5 cm
in length in its adult form.
Ascariasis is spread by ingestion of
worm eggs, usually from food grown in
soil that has been contaminated by
human faeces. In some dry, windy cli-
mates, airborne eggs may be swallowed
after being blown into the mouth.
SYMPTOMS
Light infestation may cause no symp-
toms, although mild nausea, abdominal
pain, and irregular bowel movements
may occur. A worm may be passed via
the rectum, or it may be vomited. A
large number of worms may compete
with the host for food, leading to mal-
nutrition
and
anaemia,
which,
in
children, can retard growth.
TREATMENT
The worm infestation is treated with
anthelmintic drugs,
such as levamisole,
which usually bring about complete
recovery. The worms are passed out of
the body via the rectum some days after
the drug is taken.
ascites
Excess fluid in the peritoneal cavity,
the space between the two layers of
the peritoneum (the membranes that
line the inside of the abdominal wall
and cover the abdominal organs).
CAUSES
Ascites may occur in any condition that
causes generalized
oedema
(excessive
accumulation of fluid in the body tis-
sues), such as in congestive
heart failure,
nephrotic syndrome,
and
cirrhosis
of the
liver. Ascites may occur in
cancer
if
metastases (secondary growths) from a
cancer elsewhere in the body develop in
the peritoneum. The condition also oc-
curs if
tuberculosis
affects the abdomen.
SYMPTOMS
Ascites causes abdominal swelling and
discomfort. Additionally, it may cause
breathing difficulty as a result of pres-
sure on, and the immobilization of, the
diaphragm, the sheet of muscle that
separates the thorax (the chest) from
the abdomen.
DIAGNOSIS
The doctor diagnoses the cause of asci-
tes by removing and analysing a sample
of ascitic fluid via a sterile needle
inserted through the abdominal wall.
TREATMENT
The
underlying
cause
is
treated
if
possible.
Diuretic drugs,
particularly
spir-
onolactone,
are often used to treat ascites
associated with cirrhosis. If the ascites is
causing discomfort or breathing diffi-
culty, fluid can be drained from the
peritoneal cavity.
ascorbic acid
The chemical name for
vitamin C
.
ASD
The abbreviation for
atrial septal defect
.
aseptic necrosis
Death of an area of bone tissue in the
absence of infection. The cause of asep-
tic necrosis is almost always damage to
the blood supply to bone, often as a
result of a fracture. In some cases, the
condition is associated with treatment
with
corticosteroid drugs.
Aseptic
necrosis
often
results
in
chronic
(long-term)
pain
and
may
cause stiffness in adjacent joints. Early
treatment of fractures reduces the risk
of the condition developing.
The head of the
femur
(thigh-bone)
and the
scaphoid
(a bone in the wrist)
are particularly likely to be affected.
Aseptic necrosis may be diagnosed from
X-rays
; the affected area of bone appears
denser than the surrounding bone.
aseptic technique
The creation of a germ-free environ-
ment to protect a patient from infection.
Aseptic technique is used during sur-
gery and other minor procedures, such
as the insertion of a urinary catheter. It
is also used during the care of people
suffering from diseases in which the
immune system
is suppressed, such as
leukaemia.
Such conditions result in a
weakening of the body’s natural def-
ences against infection.
All people who come in contact with
the patient must scrub their hands and
wear disposable gloves and masks and
pre-sterilized gowns. Surgical instru-
ments are sterilized in an
autoclave.
The
patient’s skin is cleaned with
antiseptic
solutions of, for example, iodine or
chlorhexidine.
In operating theatres, spe-
cial ventilation systems purify the air.
(See also
barrier nursing; isolation.)
aspartame
An
artificial sweetener
used in some
foods and drugs.
Asperger’s syndrome
A developmental disorder that is usually
first recognized in childhood because
of stilted speech, difficulties with social
interactions, and very specialized inter-
ests. Intelligence is normal or high.
Asperger’s syndrome is one of a group
of conditions known as pervasive devel-
opmental disorders; it is considered to
be an
autism spectrum disorder
(a deve-
lopmental
disorder
characterized
by
obsessive behaviour and impaired com-
72
previous page 71 BMA A Z Family Medical Encyclopedia   2004 read online next page 73 BMA A Z Family Medical Encyclopedia   2004 read online Home Toggle text on/off