wall and expel it through the VAGINA. The expelled
placenta is the afterbirth.
For further discussion of the placenta within
the context of the structures and functions of
reproduction and sexuality, please see the
overview section “The Reproductive System.”
See also AMNIOCENTESIS; AMNIOTIC FLUID; CHILD-
BIRTH; CHORIONIC VILLI SAMPLING(CVS); CONCEPTION;
HORMONE.
polycystic ovary syndrome (PCOS) A condition
in which the OVARIESproduce excessive ANDROGENS,
the male sex hormones, resulting in irregular
menstrual cycles and often anovulation (absence
of egg maturation and release). A common char-
acteristic of PCOS is the formation of multiple and
often numerous cysts within the follicles of the
ovaries. PCOS, sometimes called Stein-Leventhal
syndrome or hyperandrogenic anovulation, is a
common cause of INFERTILITYin women.
Researchers believe INSULIN RESISTANCE, an
endocrine disorder in which the cells in the body do
not appropriately respond to INSULIN, is a key factor
in the development of PCOS though do not know
the mechanisms of the relationship between the
two conditions. PCOS commonly appears among a
constellation of symptoms associated with insulin
resistance including OBESITY, HYPERLIPIDEMIA (ele-
vated levels of fatty acids in the BLOODcirculation),
ATHEROSCLEROSIS (accumulations of fatty plaques
within the walls of the arteries), CORONARY ARTERY
DISEASE(CAD), and type 2 DIABETES.
Symptoms and Diagnostic PathThe symptoms of PCOS include
- irregular menstrual cycles
- AMENORRHEA(absence of MENSTRUATION) or fre-
quent skipped menstrual periods - excessive or male pattern body HAIR(HIRSUTISM)
- male pattern thinning of the hair on the head
(ALOPECIA) - pelvic discomfort or PAIN
- inability to conceive (infertility)
- excessive or persistent ACNE
In addition, many women who have PCOS also
have HYPERTENSION (high BLOOD PRESSURE) along
with other health conditions in the insulin resist-
ance constellation (notably diabetes, hyperlipi-
demia, and obesity). Though some women who
have PCOS have irregular menstrual cycles from
MENARCHE(the onset of menstruation) or fail to
start menstruating (primary amenorrhea), many
women do not suspect they have PCOS until they
are unsuccessful in their attempts to become preg-
nant.
The diagnostic path begins with a comprehen-
sive medical examination including blood tests to
measure HORMONElevels, GLUCOSEtolerance test,
and PELVIC EXAMINATION, during which the doctor
often can palpate (feel) the enlargement and irreg-
ular shape of the ovaries that is typical with multi-
ple cysts. Transvaginal or pelvic ULTRASOUND
provides visual representation of the ovaries that
can confirm the diagnosis.Treatment Options and Outlook
Though there is no cure for PCOS, medical treat-
ments to regulate the balance of hormones in the
body often can restore normal OVULATION and
menstruation. For women who are not trying to
become pregnant, the medication of choice is an
oral contraceptive (birth control pills). Some oral
ANTIDIABETES MEDICATIONS that affect how cells
respond to insulin are also effective at improving
symptoms.
For women who are trying to become preg-
nant, FERTILITYmedications may stimulate ovula-
tion though the risk for multiple pregnancy
becomes significant. Some doctors recommend in
vitro fertilization (IVF), a method of ASSISTED
REPRODUCTIVE TECHNOLOGY(ART), rather than fertility
medications for women who have PCOS and wish
to become pregnant because IVF allows control
over the number of potential fetuses. During preg-
nancy women who have PCOS have increased
risk for spontaneous ABORTION, GESTATIONAL DIA-
BETES, PREECLAMPSIA, and PREMATURE BIRTH, though
diligent PRENATAL CAREkeeps these risks to a mini-
mum.
A surgical treatment option is ovarian drilling, a
laparoscopic OPERATIONin which the surgeon uses
electrocautery to burn selected ovarian follicles to
destroy the cysts they contain. Ovarian drilling
typically restores normal ovulation for a limited
time, which reduces symptoms overall. However,320 The Reproductive System