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Birth canal
Birth canal: The birth canal is a series of organs in women
that has several important roles in reproduction. The lower
portion of the birth canal is the vagina.
Size and location In adult women the vaginal portion of the
birth canal is about three inches long and one inch in
diameter before babies pass through it. But the vagina is
quite flexible and can stretch in both length and width as
needed, both for sexual intercourse and for childbirth. The
birth canal begins with an outer portion called the vulva.
At the other end of the vagina is a narrow opening called the
cervix, which is actually the lower part of the uterus.
Role The birth canal is the organ in women through which
babies are born naturally, although it is bypassed when a baby
is born by the surgical procedure known as a cesarean section.
Another role of the birth canal is to receive the sperm from
men to initiate sexual reproduction. Tissues from the uterus
that are sloughed off during menstruation exit the body
through the birth canal.
Conditions that affect the birth canal Trichomonas, candidiasis,
and gonorrhea are the three most common infections of the
birth canal. They are caused respectively by a protist, a
fungus, and a bacterium. Vaginitis is the general name for
any irritation of the vagina caused by infection or, rarely,
by foreign materials that have gained entrance to the birth
canal.
Warts spread by sexual intercourse can sometime affect the
lower part of the birth canal. Cancer can affect the upper
portion of the birth canal, especially the cervix. Although
cancer of the cervix, a common cancer in women over 50, can
spread and be fatal, it also can be completely cured if
detected early. Detection is accomplished with a simple test
called a Pap smear, which is usually taken as a part of a
routine physical examination by a physician specializing in
the diseases of women (a gynecologist). A Pap smear ought to
be taken at least once every three years, or annually in
women over the age of 50.
All sexually transmitted diseases, including AIDS, enter a
woman's body most often through the birth canal. Syphilis
may begin with a localized infection of the birth canal and,
if not treated, spread to other organs of the body.
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