ing, and frequency of ejaculation are among the
factors that influence the volume and content of
semen.
SEMEN NORMAL VALUES PER EJACULATION
semen volume 1.5 to 6.5 milliliters
sperm count 20 to 250 million per milliliter
pH 7.1 to 8.0
fructose 30 milligrams per milliliter
See alsoCONTRACEPTION; HEMATOSPERMIA; HYDRO-
CELE; PATHOGEN; SEXUAL INTERCOURSE; SEXUALLY TRANS-
MITTED DISEASE(STD) PREVENTION; VARICOCELE; VIRUS.
sexual dysfunction Physical or psychologic cir-
cumstances that interfere with sexual interest or
sexual activity. Most people experience some
degree of sexual dysfunction over the course of
their lifetimes. The causes of sexual dysfunction
are numerous; most are transient (improve or go
away with time). Physical illness, injury, surgery,
disability, medication side effects, emotional stress,
job pressures, CHILDBIRTHand PARENTINGresponsibil-
ities, GRIEF, DEPRESSION, and relationship discord are
among the most common factors. People who
have experienced SEXUAL ASSAULTor rape, in child-
hood or as adults, may also have difficulty estab-
lishing or maintaining healthy sexual
relationships. As well, an individual’s attitudes
toward and understanding of sex affect the nature
and quality of sexual interaction.
Painful SEXUAL INTERCOURSE, called DYSPAREUNIA,
is the most common form of physical sexual dys-
function in women. Dyspareunia may result from
insufficient vaginal lubrication (which becomes
more common after MENOPAUSE), vaginal MUSCLE
spasms (VAGINISMUS), INFLAMMATIONor irritation of
the VAGINA(VAGINITIS) or VULVA(vulvitis), PAINin the
external GENITALIA(VULVODYNIA), UTERINE PROLAPSE,
ENDOMETRIOSIS, UTERINE FIBROIDS, or perineal injury
(such as perineal tear or EPISIOTOMY repair).
Chronic PELVIC INFLAMMATORY DISEASE(PID) may also
cause pain during sex. Psychologic or emotional
factors may also contribute to dyspareunia.
The most common form of physical sexual dys-
function in men is the inability to achieve or
maintain an ERECTION (ERECTILE DYSFUNCTION),
which may result from physical or psychologic
factors. ATHEROSCLEROSIS(accumulation of plaque
deposits in the arteries that narrows the channel
for BLOODflow), DIABETES, peripheral NEUROPATHY
(damage to the small nerves that supply the
penis), long-term cigarette smoking, and medica-
tion side effects are the leading physical causes of
erectile dysfunction in men. Men may also experi-
ence pain with intercourse as a consequence of
URETHRITIS, PEYRONIE’S DISEASE, and inadequate
lubrication during penetration.
Excessive ALCOHOL use, ILLICIT DRUG USE, and
heavy or long-term cigarette smoking contribute
to sexual dysfunction in men and women. Alcohol
and many drugs, prescription or “street,” depress
LIBIDO. Alcohol affects the health of blood vessels
and nerves; long-term alcohol abuse is another
cause of erectile dysfunction in men. Cigarette
smoking also affects blood flow; NICOTINEis a pow-
erful vasoconstrictor (narrows blood vessels) and
the changes in blood oxygen levels that occur
when smoking affect the function of cells
throughout the body. These effects are most signif-
icant for NERVEcells, which require consistent lev-
els of oxygen.Symptoms and Diagnostic Path
The primary symptom of sexual dysfunction is the
reduced ability to engage in or enjoy sexual activ-
ity. Men and women may experience difficulty
achieving ORGASM(sexual climax); this is more
common in women. Psychologic and emotional
symptoms of sexual dysfunction in men or
women may include diminished libido (sex drive),
disinterest in sex, or excessive interest in sex. The
diagnostic path begins with a comprehensive med-
ical examination, including PELVIC EXAMINATIONfor
women, and discussion about factors that might
be contributing to the symptoms. The doctor may
perform additional diagnostic procedures, depend-
ing on the findings of the medical examination,
such as blood tests (men and women), cultures of
vaginal fluids (women) or any discharges (men
and women), or pelvic ULTRASOUND(women).Treatment Options and Outlook
Treatment options depend on the identified causes
of the symptoms. Treatment may be as straightfor-
ward as changing or stopping a medication that is
causing the symptoms or treating an underlying
physical condition. Often the symptoms of sexual338 The Reproductive System