vaccinationA form of immunizationin
which killed or weakened microorg-
anisms, or inactivated bacterial toxins,
are introduced into the body, usually by
injection, to sensitize the immune sys-
tem (see vaccine). If disease-causing
organisms or toxins of the same type
later enter the body, the sensitized
immune system rapidly produces anti-
bodiesthat destroy them.
vaccineA preparation given to induce
immunityagainst an infectious disease.
Most vaccines contain the organisms
(or parts of the organisms) against
which protection is sought.
Vaccines are usually given by injection
into the upper arm, but some, such as
the poliomyelitisvaccine, may be given
orally. Some vaccines require several
doses, spaced some weeks apart; others
require only 1 dose.
vacuum extractionAn obstetric pro-
cedure to facilitate the delivery of a
baby. It may be used if the second stage
of labour (see childbirth) is prolonged,
if the mother becomes exhausted, or if
the baby shows signs of fetal distress.
Vacuum suction techniques are also
used to perform early abortions.
The vacuum extraction instrument
consists of a suction cup connected to
a vacuum bottle. The suction cup is
placed on the baby’s head in the birth
canal, and the vacuum machine sucks
the baby’s scalp into the cup. The ob-
stetrician draws the baby out of the
mother’s vagina by gently pulling on the
cup with each uterine contraction.
The baby is born with a swelling on
the scalp, but this disappears after a
few days, usually without treatment.
vaginaThe muscular passage, forming
part of the female reproductive system,
between the cervixand the external
genitalia. The vagina has muscular
walls, which are highly elastic to allowsexual intercourseand childbirthand are
richly supplied with blood vessels.
vaginal bleedingBleeding, via the vagi-
na, that may come from the uterus, the
cervix, or from the vagina itself.
The most common source of bleeding
is the uterus and the most likely reason
for it is menstruation. From puberty to
the menopause, menstrual bleeding
usually occurs at regular intervals. How-
ever, problems may occur with either
the character or the timing of the bleed-
ing (see menstruation, disorders of).
Nonmenstrual bleeding from the uterus
may be due to a variety of causes. Hor-
monal drugs, such as oral contraceptives,
can cause spotting. Other possible causes
include endometritis, endometrial can-
cer (see uterus, cancer of), and fibroids.
In early pregnancy, bleeding may be a
sign of threatened miscarriage. Later in
pregnancy, it may indicate placenta
praevia or placental abruption (see
antepartum haemorrhage).
Bleeding from the cervix may be due
to cervical erosion, in which case it may
occur after intercourse. Cervicitis and
polypsmay also cause bleeding. More
seriously, bleeding may be a sign of cer-
vical cancer (see cervix, cancer of).
A possible cause of bleeding from the
vagina is injury during intercourse,
especially following the menopause,
when the walls of the vagina become
thinner and more fragile. Occasionally,
severe vaginitiscauses bleeding. Rarely,
vaginal bleeding is caused by cancer
of the vagina.
vaginal dischargeThe emission of se-
cretions from the vagina. Some mucous
secretion from the vaginal walls and
from the cervix is normal in the repro-
ductive years; its amount and nature
vary from woman to woman and at dif-
ferent times in the menstrual cycle (see
menstruation). Oral contraceptivescan
increase or decrease the discharge.
Secretions tend to be greater during
pregnancy. Sexual stimulation also pro-
duces increased vaginal discharge.
Discharge may be abnormal if it is
excessive, offensive-smelling, yellow or
green, or if it causes itching. Abnormal
discharge often accompanies vaginitis,
and may be the result of infection, as inVACCINATION VAGINAL DISCHARGEV