tract.
The procedure involves intravenous
infusion of a
contrast medium
into the
arm. The medium is carried in the blood
to the urinary system, where it passes
through the kidneys, ureters, and bladder
to be excreted in the urine. X-rays taken
at intervals show outlines of the urinary
system. IVU detects abnormalities such
as tumours and obstructions, and signs
of kidney disease.
intrinsic factor
A chemical produced
by the stomach lining that is necessary
for the absorption of vitamin B^.
introitus
A general term for the en-
trance to a body cavity or space, most
commonly used for the vagina.
introvert
A person
more concerned
with his or her inner world. Introverts
prefer to work alone, are shy, quiet, and
withdrawn when under stress. (See also
extrovert; personality.)
intubation
Most commonly, the pro-
cess of passing an
endotracheal tube
(breathing tube) into the trachea (wind-
pipe). Endotracheal intubation is carried
out if mechanical
ventilation
is needed
to deliver oxygen to the lungs. The tube
is passed through the mouth or nose
and down the throat.
The term intubation is also used to
refer to the placement of a gastric or
intestinal tube in the stomach for pur-
poses of suction or the giving of nutrients
(see
feeding, artificial).
intussusception
A condition in which
part of the intestine telescopes in on
itself, forming a tube within a tube, usu-
ally resulting in intestinal obstruction
(see
intestine, obstruction
of). The condi-
tion usually affects the last part of the
small intestine, where it joins the large
intestine. In some cases there is an
association with a recent infection. In
other cases, it may start at the site of a
polyp
or
Meckel's diverticulum.
Intussusception occurs most common-
ly in children under the age of 2. An
affected child usually develops severe
abdominal colic; vomiting is common,
and blood and mucus are often found
in the faeces. In severe cases, the blood
supply to the intestine becomes blocked
and
gangrene
, followed by
peritonitis
or
perforation
, may result. In some cases,
an
enema
can be used to force the
INTRINSIC FACTOR
IN VITRO FERTILIZATION
INTUSSUSCEPTION
LOCATION
Large
intestine ___
Appendix
Intussuscepted
segment
Small
intestine
abnormal area of bowel back into a nor-
mal position. In other cases, surgery may
be necessary to reposition the bowel.
invasive
Tending to spread throughout
body tissues; the term is usually ap-
plied to cancerous tumours or harmful
microorganisms. In an invasive medical
procedure, body tissues are penetrated
by an instrument. (See also
minimally
invasive surgery
and
noninvasive.)
inverted nipple
An indrawing of the
nipple
, which can be longstanding or
may develop in later life as a result of
changes in the breast. Causes include
normal changes associated with aging
or, in some cases, an underlying cancer.
in vitro
The performance of biological
processes in a laboratory rather than
within the body. The term in vitro liter-
ally means “in glass”.
in vitro fertilization
A method of treat-
ing
infertility
in which an egg (
ovum
) is
surgically removed from the ovary and
fertilized outside the body.
The woman is given a course of
fertility
drugs
to stimulate release of eggs from
the ovary. This is followed by
ultrasound
scanning
to check the eggs, which are
collected by
laparoscopy
immediately
before ovulation. They are then mixed
with sperm in the laboratory. Two, or
sometimes more, fertilized eggs are
replaced into the uterus. If they become
safely implanted in the uterine wall, the
pregnancy usually continues normally.
Only about 1
in 10 couples undergoing
in vitro fertilization achieves pregnancy
at the
1
st attempt, and many attempts
317
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