interruptus; hormonal methods, includ-
ing the use of oral contraceptives,
implants, and injections (see contracep-
tives, injectable); intrauterine devices
(see IUDs); postcoital methods (see
contraception, emergency); or steriliza-
tion of the male (see vasectomy) or
female (see sterilization, female).
contraception, barrier methods of
The use of a device and/or a chemical to
stop spermreaching an ovum, prevent-
ing fertilizationand pregnancy. Barrier
methods also help prevent the sexual
transmission of diseases such as AIDS,
genital herpes (see herpes, genital), and
viral hepatitis (see hepatitis, viral).The male condomis one of the most
widely used barrier contraceptives. Fe-
malecondoms (see condom, female) are
similar to, but larger than, male condoms.
Other female barrier methods include
the diaphragm (see diaphragm, contra-
ceptive), a hemispherical dome of thin
rubber with a metal spring in the rim to
hold it in place against the vaginal wall,
blocking the entrance to the cervix. It is
used with a spermicide. A cervical cap
(see cap, cervical) is an alternative to the
diaphragm. The contraceptive sponge,
which is a disposable, circular, poly-
urethane foam sponge impregnated with
spermicide, is inserted high in the vagi-
na and left in place for at least 6 hours
after intercourse.
Spermicides, in the form of aerosol
foams, creams, gels, and pessaries, are
placed in the vagina as close as possible
to the cervix shortly before intercourse.CONTRACEPTION, BARRIERtypes. Hard plastic lenses give good
vision, are long-lasting and durable, inex-
pensive, and easy to maintain. However,
they are sometimes difficult to tolerate
and mayfall out. Hard gas-permeable
lenses are more comfortable because
they allow oxygen to pass through to the
eye, but are less durable. Soft lenses are
the most comfortable because of their
high water content. Disposable soft lens-
es are for single-use only; extended
wear lenses are worn for up to a month.
Other types of lenses include rigid,
scleral lenses that cover the whole of
the front of the eye and are used to dis-
guise disfigurement due to injury or
disease; bifocal contact lenses; and
toric contact lenses with an uneven sur-
face curvature to correct astigmatism.
Hard plastic contact lenses may cause
abrasion of the cornea if they are worn
for too long. Soft lens wearers some-
times develop sensitivity of the eyes and
lids. Other problems that may occur
with any type of contact lens include
infections and redness of the eye.
contact tracingA service, provided by
clinics treating sexually transmitted infec-
tions, in which contacts of a person
diagnosed as having sexually transmit-
ted infection are traced and encouraged
to be examined and treated. Contact
tracing is also used in cases of infec-
tions such as tuberculosis, meningitis,
and imported tropical diseases.
contagiousA term used to describe a
disease that can be transferred from per-
son to person by ordinary social contact.
All contagious diseases, such as the
common cold or chickenpox, are infec-
tious. The term contagious does not apply
to the many infectious diseases, such as
typhoid, syphilis, or AIDS, which are
spread by other means.
contraceptionThe control of fertility to
prevent pregnancy. Methods prevent ovu-
lationin the woman, stop sperm from
meeting an ovumin the fallopian tube
(preventing fertilization), or prevent a
fertilized ovum implanting in the uterus.
Methods of contraception include
total or periodic abstinence from sexual
intercourse(see contraception, natural
methods of); barrier methods (see con-
traception, barrier methods of); coitus
CONTACT TRACING CONTRACEPTION, BARRIER METHODS OF
C
FEMALE
CONDOMCERVICAL
CAPDIAPHRAGMMALE
CONDOM