Webster's New World Medical Dictionary

intravenous pyelogram
An X-ray of the kidneys
and urinary tract. Abbreviated IVP. Structures are
made visible on an IVP by the injection of a contrast
material.
intravenous tension
The pressure of the blood
within a vein. Also known as venous pressure.
intraventricular
In the ventricle of the heart or
the brain.
introitus
An entrance that goes into a canal or
hollow organ.
introitus, facial canal
The entrance to the facial
canal, a passage in the temporal bone of the skull
through which the facial nerve travels.
introitus, vaginal
The vaginal opening.
intron
Part of a gene that is initially transcribed
into the primary RNA transcript but is later removed
from it when the exon sequences on either side of it
are spliced together. Also known as intervening
sequence.
intubate
To put a tube in, commonly used to
refer to the insertion of a breathing tube into the tra-
chea for mechanical ventilation. For example, as a
life-saving measure, an emergency room physician
might intubate a patient who is not breathing ade-
quately so that the lungs can be ventilated.
intussusception
Infolding (prolapse) of a por-
tion of the intestine within another immediately
adjacent portion of intestine, which predominantly
affects children. Intussusception decreases the sup-
ply of blood to the affected part of the intestine and
frequently leads to intestinal obstruction. The pres-
sure created by the two walls of the intestine press-
ing together causes inflammation and swelling, and
it reduces the blood flow. Death of bowel tissue can
occur, with significant bleeding, perforation,
abdominal infection, and shock occurring very rap-
idly. Most cases of intussusception occur in children
between 5 months and 1 year of age. Symptoms
begin with sudden, loud crying in an infant, with the
baby drawing the knees up to the chest due to
abdominal cramping. The pain and crying are inter-
mittent but recur frequently and increase in inten-
sity and duration. Fever is common. As the
condition progresses, the infant becomes weak and
then shows signs of shock, including pale color,
lethargy, and sweating. About half of afflicted infants
pass a bloody, mucousy (“currant jelly”) stool. The
cause of intussusception is not known, although
viral infections of the intestine may contribute to
intussusception in infancy. In older children or
adults, the presence of polyps or a tumor may trig-
ger intussusception. Early diagnosis is very impor-
tant. On examining the abdomen, a physician may
feel a mass. Abdominal X-rays may suggest intestinal
obstruction, but a barium enema is needed to show
the characteristic telescoping of the bowel. In some
cases, the intestinal obstruction can be relieved with
a barium or air enema. If the obstruction cannot be
reduced by a barium enema, surgery is required for
treatment.