The male reproductive organs include the penis, scrotum, testes, duct system, and accessory reproductive glands.

Located in the breasts, the mammary glands are specialized accessory glands that secrete milk. Although present in both sexes, they normally function only in females.

Female genitalia include the following external structures, collectively known as the vulva: mons pubis (or mons veneris), labia majora, labia minora, clitoris, and the vestibule. The perineum is the external region between the vulva and the anus. The size, shape, and color of these structures —as well as pubic hair distribution and skin texture and pigmentation—vary greatly among individuals. Furthermore, these external structures undergo distinct changes during the life cycle.

The internal structures of the female genitalia include the vagina, cervix, uterus, fallopian tubes (or oviducts), and ovaries.

Maturation of the hypothalamus and the resultant increase in hormone levels initiate puberty. In the young girl, the appearance of pubic and axillary hair (pubarche) and the characteristic adolescent growth spurt follow breast development (thelarche)—the first sign of puberty. The reproductive system begins to undergo a series of hormone-induced changes that result in menarche, or the onset of menstruation (or menses).

The menstrual cycle consists of three different phases: menstrual, proliferative (estrogen dominated), and secretory (progesterone dominated). (See Understanding the menstrual cycle.)

At the end of the secretory phase, the uterine lining is ready to receive and nourish a zygote. If fertilization doesn’t occur, increasing estrogen and progesterone levels decrease LH and FSH production. Because LH is needed to maintain
the corpus luteum, a decrease in LH production causes the corpus luteum to atrophy and halt the secretion of estrogen and progesterone. The thickened uterine lining then begins to slough off, and menstruation begins.

In the nonpregnant female, LH controls the secretions of the corpus luteum, thereby increasing the amount of progesterone in the bloodstream. In the pregnant woman, human chorionic gonadotropin (hCG), produced by the nascent placenta, controls these secretions.

If fertilization and pregnancy occur, the endometrium grows even thicker and vascular ingrowth occurs. After implantation of the zygote (5 to 6 days after fertilization), the endometrium becomes the decidua. Trophoblastic cells produce hCG soon after implantation, stimulating the corpus luteum to continue secreting estrogen and progesterone, which prevents further ovulation and menstruation.

hCG continues to stimulate the corpus luteum until the placenta (the vascular organ that develops to transport materials to and from the fetus) forms and starts producing its own estrogen and progesterone. After the placenta takes over hormone production, secretions of the corpus luteum are no longer needed to maintain the pregnancy, and the corpus luteum gradually decreases its function and begins to degenerate. This is termed luteoplacental shift and commonly occurs by the end of the first trimester.

Sexual maturation, or puberty, can be affected by various congenital and endocrine disorders. The timing of puberty may be too early (precocious
puberty) or too late (delayed puberty). Precocious puberty is the onset of sexual maturation before age 9 in boys and before age 6 in girls. It’s more common in girls than in boys. The cause is usually idiopathic but can result from central nervous system or congenital abnormalities.

In delayed puberty, there’s no evidence of the development of secondary sex characteristics in boys by age 14 or girls by age 13. There’s usually no evidence of hormonal abnormalities. The hypothalamic-pituitary-ovarian axis, a system that stimulates and regulates the production of hormones necessary for normal sexual development and function, is intact, but maturation is slow. The cause is unknown.

Complex hormonal interactions determine the normal function of the female reproductive tract and require an intact hypothalamic-pituitaryovarian axis. A defect or malfunction of this system can cause infertility due to insufficient gonadotropin secretions (both LH and FSH). The ovary controls—and is controlled by—the hypothalamus through a system of negative and positive feedback mediated by estrogen production. Insufficient gonadotropin levels may result from infections, tumors, or neurologic disease of the hypothalamus or pituitary gland. A mild hormonal imbalance in gonadotropin production and regulation, possibly caused by polycystic disease of the ovary or abnormalities in the adrenal or thyroid gland that adversely affect hypothalamic-pituitary functioning, may sporadically inhibit ovulation. Because gonadotropins are released in a pulsatile fashion, a significant disturbance in this pulsatility will adversely affect ovulatory function. Marijuana use can delay the onset of puberty because it blocks the release of gonadotropin-releasing hormone from the hypothalamus, which ultimately delays gonadal function.

Male hypogonadism, or an abnormal decrease in gonad size and function, results from decreased androgen production in males, which may impair spermatogenesis (causing infertility) and inhibit the development of normal secondary sex characteristics. The clinical effects of androgen deficiency depend on age at onset. Primary hypogonadism results directly from interstitial (Leydig’s cell) cellular or seminiferous tubular damage of the testes due to faulty development or mechanical damage. Androgen deficiency causes increased secretion of gonadotropins by the pituitary in an attempt to increase the testicular functional state and is therefore termed hypergonadotropic hypogonadism. This form of hypogonadism includes Klinefelter’s syndrome (47 XXY), Reifenstein’s syndrome, male Turner’s syndrome, Sertoli-cell-only syndrome, anorchism, orchitis, and aftereffects of irradiation.

Secondary hypogonadism is due to faulty interaction within the hypothalamic-pituitary axis, resulting in failure to secrete a normal level of gonadotropins, and is therefore termed hypogonadotropic hypogonadism. This form of hypogonadism includes hypopituitarism, isolated FSH deficiency, isolated LH deficiency, Kallmann’s syndrome, and Prader-Willi syndrome. Depending on the patient’s age at onset, hypogonadism may cause eunuchism (complete gonadal failure) or eunuchoidism (partial failure).

Signs and symptoms vary depending on the specific cause of hypogonadism. Some characteristic findings may include delayed bone maturation; delayed puberty; infantile penis and small, soft testes; less than average muscle development and strength; fine, sparse facial hair; scant or absent axillary, pubic, and body hair; and a high-pitched, effeminate voice. In an adult, hypogonadism diminishes sex drive and potency and causes regression of secondary sex characteristics.

Alterations in menstruation include the absence of menses, abnormal bleeding patterns, or painful menstruation. Menopause is the cessation of menstruation. It results from a complex continuum of physiologic changes —the climacteric —caused by declining ovarian function. The climacteric produces various changes in the body, the most dramatic being the cessation of menses.

The climacteric, a normal gradual reduction in ovarian function due to aging, begins in most women between ages 45 and 50. Perimenopause begins 5 to 10 years (sometimes more) before menopause and commenses with vasomotor symptoms and irregular menses. Menopause begins 12 months after final menses and is characterized by the continuation of vasomotor symptoms as well as urogenital symptoms (vaginal dryness and dyspareunia).

Premature ovarian failure, or premature menopause, the gradual or abrupt cessation of menstruation before age 40, occurs without apparent cause in about 1% of women in the United States. Factors that may precipitate premature ovarian failure include malnutrition, debilitation, extreme emotional stress, pelvic irradiation, viral agents, and surgical procedures that impair ovarian blood supply. Artificial menopause may follow radiation therapy or surgical procedures, such as removal of both ovaries (bilateral oophorectomy). Other causes
of premature ovarian failure include a decreased number of germ cells, chromosomal abnormalities, gonadotropin secretion defects, and autoimmune disorders. Hysterectomy decreases the interval before menopause, even when the ovaries aren’t removed. It’s speculated that hysterectomy may decrease ovarian blood flow in some fashion.

Ovarian failure, in which no ova are produced, may result from a functional ovarian disorder from premature ovarian failure. Amenorrhea is a natural consequence of ovarian failure.

Pain is commonly associated with the menstrual cycle; in many common diseases of the female reproductive tract, such pain may follow a cyclic pattern. A patient with endometriosis, for example, may report increasing premenstrual pain that decreases at the end of menstruation. For a description of the types of abnormal menstrual bleeding, (see Abnormal premenopausal bleeding.)

Sexual dysfunction includes arousal problems, orgasmic problems, and sexual pain (dyspareunia, vaginismus). Dysfunction may be caused by a general medical condition, psychological condition, substance use or abuse, or a combination of these factors.

Arousal disorder is an inability to experience sexual pleasure. According to the Diagnostic and Statistical Manual of Mental Disorders, 4th edition, Text Revision (DSM-IV-TR), the essential feature is a persistent or recurrent inability to attain or to maintain an adequate lubricationswelling response of sexual excitement until completion of the sexual act. Orgasmic disorder, according to the DSM-IV-TR, is a persistent or recurrent delay in or absence of orgasm after a normal sexual excitement phase.

Both arousal and orgasmic disorders are considered primary if they exist in a female who has never experienced sexual arousal or orgasm; they’re secondary when a physical, mental, or situational condition has inhibited or obliterated a previously normal sexual function. The prognosis is good for temporary or mild disorders resulting from misinformation or situational stress but is guarded for disorders that result from intense anxiety, chronically discordant relationships, psychological disturbances, or drug or alcohol abuse in either partner.

The following factors, alone or in combination, may cause an arousal or orgasmic disorder:

♦ certain drugs, including central nervous system depressants, alcohol, street drugs and, rarely, hormonal contraceptives

♦ general systemic illnesses, diseases of the endocrine or nervous system, or diseases that impair muscle tone or contractility

♦ gynecologic factors, such as chronic vaginal or pelvic infection or pain, congenital anomalies, and genital cancer

♦ inadequate or ineffective stimulation

♦ psychological factors, such as performance anxiety, early traumatic sexual experiences, guilt, depression, or unconscious conflicts about sexuality

♦ relationship problems, such as poor communication, hostility, interpersonal disharmony, or ambivalence toward the partner, fear of abandonment or independence, or boredom with sex

♦ stress and fatigue.

All of these factors may contribute to involuntary inhibition of the orgasmic reflex. Another crucial factor is the fear of losing control of
feelings or behavior. Whether these factors produce sexual dysfunction—as well as the type of dysfunction they produce—depends on how well the woman copes with the resulting pressures. Physical factors may also cause arousal or orgasmic disorder.

Female sexual function and responses decline, along with estrogen levels, in the perimenopausal period. The decrease in estradiol levels during menopause affects nerve transmission and response in the peripheral vascular system. As a result, the timing and degree of vasoconstriction during the sexual response is affected, vasocongestion decreases, muscle tension decreases, lubrication decreases, and contractions are fewer and less intense during orgasm.

A female with arousal disorder has limited or absent sexual desire and experiences little or no pleasure from sexual stimulation. Physical signs of this disorder include lack of vaginal lubrication or absence of signs of genital vasocongestion. Dyspareunia is genital pain associated with intercourse. Insufficient lubrication is the most common cause. Other physical causes of dyspareunia include:

♦ disorders of the surrounding viscera (including residual effects of pelvic inflammatory disease or disease of the adnexal and broad ligaments)

♦ endometriosis

♦ genital, rectal, or pelvic scar tissue

♦ infections of the genitourinary tract (acute or chronic).

Other possible physical causes include:

♦ allergic reactions to diaphragms, condoms, or other contraceptives

♦ benign and malignant growths and tumors

♦ deformities or lesions of the introitus or vagina

♦ intact hymen

♦ radiation to the pelvis.

Psychological causes include:

♦ anxiety caused by a new sexual partner or technique

♦ fear of pain or injury during intercourse

♦ fear of pregnancy or injury to the fetus during pregnancy

♦ guilty feelings about sex

♦ mental or physical fatigue

♦ previous painful experience, including sexual abuse.

Vaginismus is an involuntary spastic constriction of the lower vaginal muscles, usually from fear of vaginal penetration. This disorder may coexist with dyspareunia and, if severe, may prevent intercourse (a common cause of unconsummated marriages). Vaginismus may be physical or psychological in origin. It may occur spontaneously as a protective reflex to pain or result from organic causes, such as hymenal abnormalities, genital herpes, obstetric trauma, and atrophic vaginitis.

Psychological causes may include:

♦ childhood and adolescent exposure to rigid, punitive, and guilt-ridden attitudes toward sex

♦ early traumatic experience with pelvic examinations

♦ fear of pregnancy, sexually transmitted disease, or cancer

♦ fear resulting from painful or traumatic sexual experiences, such as incest or rape.

In males, the normal sexual response involves erection, emission, and ejaculation. Sexual dysfunction is the impairment of one or all of these processes.

Erectile disorder, or impotence, refers to inability to attain or maintain penile erection sufficient to complete intercourse. Transient periods of impotence aren’t considered dysfunction and probably occur in half the adult males. Erectile disorder affects all age-groups but increases in frequency with age.

With aging, males experience a gradual decline in their serum total and free testosterone levels. This decline may affect both the male libido and sexual function.

Psychogenic factors (guilt, fear, depression) are responsible for 50% to 60% of the cases of erectile dysfunction; organic factors, for the rest. In some patients, psychogenic and organic factors (chronic disease, paralysis, consequence of a surgical procedure) coexist, making isolation of the primary cause difficult.

Most problems with emission and ejaculation usually have structural causes.

Structural defects of the male reproductive system may be congenital or acquired. Testicular disorders, such as cryptorchidism or torsion, may result in infertility.

In cryptorchidism, a congenital disorder, one or both testes fail to descend into the scrotum, remaining in the abdomen or inguinal canal or at the external ring. If bilateral cryptorchidism persists untreated into adolescence, it may result in sterility, make the testes more vulnerable to trauma, and significantly increase the risk for testicular cancer, particularly germ cell tumors. It should be corrected between the ages of 12 and 24 months to reduce the risk of male infertility. In about 75% of affected infants, the testes descend spontaneously during the
first year; in the rest, the testes may descend through puberty.

The testes of an older male may be slightly smaller than those of a younger male, but they should be equal in size, smooth, freely moveable, and soft, without nodules. The left testis is commonly lower than the right.

Benign prostatic hyperplasia is a disorder of prostate enlargement due to androgen-induced growth of prostate cells. It’s more prevalent with aging and may result in urinary obstructive symptoms.

Hypospadias is the most common penile structural abnormality. The midline fusion of the urethral folds is incomplete, so the urethral meatus opens on the ventral (anterior, or “belly”) surface of the penis. In epispadias, the urethral meatus is located on the dorsal (posterior, or “back”) surface of the penis.

Priapism is prolonged, painful erection in the absence of sexual stimulation. It results from arteriovenous shunting within the corpus cavernosum that leads to obstructed venous outflow from the penis. The most common cause is drug therapy for erectile dysfunction. It’s also associated with the use of antihypertensives, anticoagulants, cocaine, corticosteroids, and amphetamines. In children it may be associated with sickle cell disease, leukemia, blood clots, or pelvic tumors. Without prompt treatment it can lead to ischemic fibrosis and infertility.

A urethral stricture is a narrowing of the urethra caused by scarring. It may result from trauma, surgery (adhesions), or infection. Common complications include prostatitis and secondary infection.

During the first 3 years of life, congenital adhesions between the foreskin and the glans penis separate naturally with penile erections. Phimosis is a condition in which the foreskin can’t be retracted over the glans penis; it can be congenital or acquired (from forceful retraction) or can result from poor hygiene or chronic infection. Paraphimosis is a condition in which the foreskin is retracted behind the coronal sulcus; the penis becomes constricted, causing edema of the glans. Severe paraphimosis is a surgical emergency.

To prevent threatened spontaneous abortion, millions of women took diethylstilbestrol (DES) between 1946 and 1971. Men whose mothers took DES during their 8th to 16th weeks of pregnancy experienced structural abnormalities, such as urethral meatal stenosis, hypospadias, epididymal cysts, varicoceles, cryptorchidism, and decreased fertility.

Abnormal uterine bleeding refers to abnormal endometrial bleeding without recognizable organic lesions. Abnormal uterine bleeding is the indication for almost 25% of gynecologic surgical procedures. The prognosis varies with the cause. Correction of hormonal imbalance or structural abnormality yields a good prognosis.

Amenorrhea is the abnormal absence or suppression of menstruation. Absence of menstruation is normal before puberty, after menopause, or during pregnancy and lactation; it’s abnormal— and therefore pathologic—at any other time. Primary amenorrhea is the absence of menarche in an adolescent (age 16 and older). Secondary amenorrhea is the failure of menstruation for at least 3 cycle intervals or 6 months after the normal onset of menarche. Primary amenorrhea occurs in 0.3% of women; secondary amenorrhea is seen in 1% to 3% of women. Prognosis varies, depending on the specific cause. Surgical correction of outflow tract obstruction is usually curative.

Although most men age 50 and older have some prostatic enlargement, in benign prostatic hyperplasia (BPH)—also known as benign prostatic hypertrophy or nodular hyperplasia—the prostate gland enlarges enough to compress the urethra and cause overt urinary obstruction. (See Prostatic enlargement.) Depending on the size of the enlarged prostate, the age and health of the patient, and the extent of obstruction, BPH is treated symptomatically or surgically. BPH is common, affecting 40% to 50% of men ages 50 to 60, and more than 80% of men age 80 and older. It also affects about 8% of men ages 31 to 40.