T
TESTIS, UNDESCENDED
TESTIS, TORSION OF
most common around puberty. It is
more likely to occur if the testis is
unusually mobile within the scrotum.
Diagnosis is by physical examination.
Surgery is performed to untwist the testis
and anchor it in the scrotum with small
stitches to prevent recurrence. If irrever-
sible damage has occurred,
orchidectomy
is performed. In either case, the other tes-
tis is anchored to the scrotum to prevent
torsion on that side. With prompt treat-
ment, recovery of the testis is complete.
testis, undescended A testis that has
failed to descend from the abdomen to
the
scrotum
. The condition usually affects
only
1
testis and occurs in about
1
per
cent of full-term and
10
per cent of pre-
mature male babies. An undescended
testis often descends within months of
birth but rarely descends after this time.
An undescended testis does not de-
velop normally, is incapable of normal
sperm production, and is at increased
risk of developing testicular cancer (see
testis, cancer of
). If both testes are
undescended,
infertility
results.
A diagnosis is made during a physical
examination after birth or later in infancy.
Treatment is by
orchidopexy
, which usu-
ally reduces the risk of later infertility or
testicular cancer (see
testis, cancer of
). A
poorly developed undescended testis
may be removed if the other is normal.
test meal A procedure to measure the
output of acid by the
stomach.
A naso-
gastric tube
is passed into the stomach
after an overnight fast, and a sample of
gastric fluid is sucked up through the
tube. An injection of
histamine
or, more
usually, pentagastrin (a synthetic prepa-
ration of the hormone gastrin) is given;
further samples of stomach fluid are
taken at intervals for up to
2
hours and
analysed for hydrochloric acid content.
The test is used for people thought to
be suffering from
Zollinger-Ellison syn-
drome
, and to confirm the absence of
stomach acid in people with pernicious
anaemia (see
anaemia, pernicious).
testosterone The main
androgen hor-
mone
(male sex hormone). It stimulates
bone and muscle growth and sexual
development. It is produced by the
testes
and, in very small amounts, the
ovaries.
Synthetic or animal testosterone is
used to stimulate delayed
puberty
or
treat some forms of male
infertility
.
tests, medical Tests may be performed
to investigate the cause of symptoms
and establish a diagnosis, to monitor
the course of a disease, or to assess
response to treatment. A medical test-
ing programme carried out on apparently
healthy people to find disease at an early
stage is known as
screening
.
The accuracy of a test is based on its
sensitivity (ability to correctly identify
diseased subjects), specificity (ability to
correctly identify healthy subjects), and
predictive value. The predictive value is
determined by a mathematical formula
that involves the number of accurate
test results and the total number of tests
performed. The best tests have both
high specificity and high sensitivity, and
therefore high predictive value.
tetanus A serious, sometimes fatal, dis-
ease of the
central nervous system
caused
by infection of a wound with spores of
the bacterium
Clostridium tetani.
The
spores live mainly in soil and manure
but are also found elsewhere, including
in the human intestine. When the spores
infect poorly oxygenated tissues they
multiply and produce a
toxin
that acts
on the nerves controlling muscle acti-
vity. The most common symptom of this
is
trismus
(commonly known as lockjaw).
Other symptoms include stiffness of the
abdominal and back muscles, and con-
traction of facial muscles, producing a
fixed grimace. There may also be a fast
TETANUS
544
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