1038
UNIT 5
Continuity
27
slow-growing cancer, and American Cancer Society guidelines
advise women to have one yearly until age 65, at which time
this monitoring can be stopped if there have been no abnormal
results in the past 10 years. However, the Federal Government
Source for Women’s Health recommends a Pap smear be con-
ducted every two years in women ages 21 to 30, and yearly over
age 30. If results for three years in a row are negative, the physi-
cian may suggest doing the tests farther apart and discontinuing
them a±er age 65.
When results are inconclusive, a test for the sexually transmit-
ted human papillomavirus (HPV), the cause of most cervical can-
cers, can be done from the same Pap sample or a blood sample.
Gardasil
, a three-dose vaccine that protects against HPV-
induced cervical cancer, is the latest addition to the official child-
hood immunization schedule. It is recommended for all 11- and
12-year-old girls, although it may be administered to girls as
young as 9. In unexposed girls, the vaccine specifically blocks
two cancer-causing kinds of HPV as well as two additional types
of HPV which are not associated with cervical cancer. All four
types of the virus are associated with genital warts and mild Pap
test abnormalities. Whether this vaccine will become a require-
ment for school is presently decided on a state-to-state basis.
Supports of the Uterus
Te uterus is supported laterally by the
mesometrium
(“mesentery of the uterus”) portion of the broad
ligament (Figure 27.14). More inferiorly, the
cardinal
(
lateral
cervical) ligaments
extend from the cervix and superior vagina
to the lateral walls of the pelvis, and the paired
uterosacral liga-
ments
secure the uterus to the sacrum posteriorly. Te uterus
is bound to the anterior body wall by the fibrous
round liga-
ments
, which run through the inguinal canals to anchor in the
subcutaneous tissue of the labia majora. Tese ligaments allow
the uterus a good deal of mobility, and its position changes as
the rectum and bladder fill and empty.
Homeostatic Imbalance
27.6
Despite its many anchoring ligaments, the uterus is principally
supported by the muscles of the pelvic floor, namely those of the
urogenital and pelvic diaphragms (²able 10.7). Tese muscles
stretch and sometimes tear during childbirth. Subsequently, the
unsupported uterus may sink inferiorly, until the tip of the cer-
vix protrudes through the external vaginal opening. Tis condi-
tion is called
prolapse of the uterus
.
Te undulating course of the peritoneum produces several
cul-de-sacs, or blind-ended peritoneal pouches. Te most im-
portant of these are the
vesicouterine pouch
(ves
0
i-ko-u
9
ter-in)
between the bladder and uterus, and the
rectouterine pouch
be-
tween the rectum and uterus (see Figure 27.12).
The Uterine Wall
Te wall of the uterus is composed of three
layers (Figure 27.14):
Perimetrium
, the incomplete outermost serous layer.
Myometrium
(mi
0
o-me
9
tre-um; “muscle of the uterus”),
the bulky middle layer, composed of interlacing bundles of
smooth muscle. Te myometrium contracts rhythmically
during childbirth to expel the baby from the mother’s body.
Homeostatic Imbalance
27.4
Te fact that the uterine tubes are not continuous with the ova-
ries places women at risk for
ectopic pregnancy
, in which an
oocyte fertilized in the peritoneal cavity or distal portion of the
uterine tube begins developing there. Because the tube lacks
adequate mass and vascularization to support a full-term preg-
nancy, ectopic pregnancies tend to naturally abort, o±en with
substantial bleeding.
Another potential problem is infection spreading into the peri-
toneal cavity from other parts of the reproductive tract. Sexually
transmitted microorganisms, including gonorrhea bacteria, some-
times infect the peritoneal cavity in this way, causing an extremely
severe inflammation called
pelvic inflammatory disease (PID)
.
Unless treated promptly with broad-spectrum antibiotics, PID can
cause scarring of the narrow uterine tubes and of the ovaries, re-
sulting in sterility. Scarring and closure of the uterine tubes, which
have an internal diameter as small as the width of a human hair
in some regions, is one of the major causes of female infertility.
The Uterus
Te
uterus
(Latin for “womb”) is located in the pelvis, ante-
rior to the rectum and posterosuperior to the bladder (Fig-
ures 27.12 and 27.14). It is a hollow, thick-walled, muscular
organ that receives, retains, and nourishes a fertilized ovum.
In a fertile woman who has never been pregnant, the uterus
is about the size and shape of an inverted pear, but it is usu-
ally larger in women who have borne children. Normally, the
uterus flexes anteriorly to some extent where it joins the va-
gina (see Figure 27.12), causing the uterus as a whole to be
inclined forward, or
anteverted
. However, the organ is fre-
quently turned backward, or
retroverted
, in older women.
Te major portion of the uterus is referred to as the
body
(Figures 27.12 and 27.14). Te rounded region superior to the
entrance of the uterine tubes is the
fundus
, and the slightly nar-
rowed region between the body and the cervix is the
isthmus
.
Te
cervix
of the uterus is its narrow neck, or outlet, which
projects into the vagina inferiorly.
Te cavity of the cervix, called the
cervical canal
, communi-
cates with the vagina via the
external os
(
os
5
mouth) and with
the cavity of the uterine body via the
internal os
. Te mucosa of
the cervical canal contains
cervical glands
that secrete a mucus
that fills the cervical canal and covers the external os, presumably
to block the spread of bacteria from the vagina into the uterus.
Cervical mucus also blocks sperm entry except at midcycle, when
it becomes less viscous and allows sperm to pass through.
Homeostatic Imbalance
27.5
Cancer of the cervix strikes about 450,000 women worldwide
each year, killing about half. It is most common among women
between the ages of 30 and 50. Risk factors include frequent cer-
vical inflammations, sexually transmitted infections (including
genital warts), and multiple pregnancies. Te cancer cells arise
from the epithelium covering the cervical tip.
In a
Papanicolaou
(
Pap
)
smear
, or cervical smear test, some
of these cells are scraped away and then examined for abnor-
malities. A Pap smear is the most effective way to detect this
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