Since the beginning of recorded history, the external genitalia and the urologic system have been of special interest to people. Kidney stones and urologic surgery were well described in antiquity. One of the earliest reported kidney stones was found in a young boy who lived about 7000 BCE.
Circumcision is one of the oldest known surgical procedures in medicine. Male circumcision has been widely practiced as a religious rite since ancient times. An initiatory rite of Judaism, circumcision is also practiced by Muslims, for whom it signifies spiritual purification. Although the origin is unknown, circumcision is often depicted on the walls of temples dating from 3000 bce. In the Egyptian Book of the Dead, it is written, ''The blood falls from the phallus of the Sun God as he starts to incise himself.'' By the time of the Roman takeover of Egypt in 30 BCE, the practice of circumcision had a ritual significance, and only circumcised priests could perform certain religious rites. The Hindus regarded the penis and testicles as a symbol of the center of life and sacrificed the prepuce as a special offering to the gods.
The Bible has many urologic references. In Genesis 17:7, Abraham makes a covenant with God for the Jews. He is told in Genesis 17:14, ''And the uncircumcised male who is not circumcised in the flesh of his foreskin, that soul shall be cut off from his people;he hath broken My covenant.'' In Leviticus 12:3, the Jews were told, ''And in the eighth day the flesh of his foreskin shall be circumcised.'' Leviticus 15:2-17 deals with discharges that render a man unclean. Today, it is estimated that one in every six men worldwide is circumcised. There are more than 15 million postinfancy circumcisions a year, and thus it is one of the most common surgical procedures.
The Bible, Hindu literature, and Egyptian papyri described a disease now presumed to be gonorrhea. The Mesopotamian tablets described a variety of cures, such as this: ''If a man's penis on occasions of his pleasure hurts him, boil beer and milk and anoint him from the pubis.'' Avicenna's Canon of Medicine (1000 ce) was considered the authoritative medical text for centuries and described placing a louse in the penis to counteract a penile discharge.
Gonorrhea was probably first named by Galen in the second century CE. Gonorrhea is the Greek translation of ''a flow of offspring.'' Galen apparently thought that the purulent discharge was a leakage of semen. Many terms have been used to describe gonorrhea throughout the years. Perhaps the most common is clap, a name used for the past 400 years. It is thought that the term clap was derived from a specific area in Paris known for prostitution called ''Le Clapier.''
It is unclear when the scourge of syphilis began. There was much confusion between syphilis and gonorrhea. It was thought that gonorrhea was the first stage of syphilis. The cause of these diseases was also unknown. Many believed that syphilis was caused by floods, eating disguised human meat, or drinking poisoned water. It was not until 1500, when syphilis was pandemic in Europe, that the venereal origins of both diseases were understood. It is now believed that syphilis was introduced on the European continent in 1492 by the returning sailors who had been traveling with Columbus. After France's invasion of Italy and the siege of Naples in 1495, syphilis became rampant throughout Europe. The King's pox and the French pox were common terms for syphilis.
Benign prostatic hyperplasia (BPH) is the most common benign neoplasm in aging men. It has been estimated that by 60 years of age, the prevalence is greater than 50%, and by 85 years of age, the prevalence approaches 90%. In addition, by 80 years of age, one in every four men require some form of treatment for relief of symptomatic BPH. More than 300,000 surgical procedures are performed in the United States annually for BPH, most commonly a transurethral resection of the prostate (TURP).
Cancer of the genitourinary system is common. In the United States, in 2007, prostate cancer accounted for 33% of all cancer cases in men. It accounted for 9% of all cancer deaths and was the third most common cause of cancer deaths after lung/bronchus cancer (31%) and colon/rectum cancer (10%). In 2007, there were 218,890 new cases of prostate cancer and 27,050 deaths from the disease in the United States, and thus this diagnosis is the most common nondermatologic malignancy to develop in men and the third most common cause of cancer deaths in men.
The highest incidence rate for prostate cancer is in African Americans (54.8 per 100,000);for white persons, it is 23.7 per 100,000. The lowest incidence rate is in Asians and Pacific Islanders (10.7 per 100,000). The lifetime probability for development of prostate cancer is 16.7% (one per six). For a 50-year-old man with a 75-year life expectancy, the lifetime risk for development of microscopic prostate cancer is 42%;the risk for development of clinically evident prostate cancer is 10%;and the risk for development of fatal prostate cancer is 3%. Approximately 95% of all prostate cancers arise from an area of the gland where it can be readily detected by rectal examination.
Cancer of the urinary bladder accounted for an additional 6% of cancer cases but only 3% of all cancer deaths. In 2007, there were 67,160 new cases (50,040 in men, 17,120 in women) of cancer of the urinary bladder in the United States and 13,750 deaths from the disease. Cancer of the urinary bladder is the fourth most common malignancy among men and the eighth most frequent among women. Approximately 260,000 new cases of urinary bladder cancer are diagnosed worldwide every year. The highest incidence rates for bladder cancer are found in industrialized countries such as the United States, Canada, France, Denmark, Italy, and Spain. The lowest rates are in Asia and South America, where the incidence is only about 30% as high as in the United States. Cigarette smoking is an established risk factor for cancer of the urinary bladder. It is estimated that about 50% of these cancers in men and 30% in women are linked to smoking. Occupational exposures may account for up to 25% of all urinary bladder cancers. Most of the occupationally accrued risk is attributable to exposure to a group of chemicals known as arylamines. Occupations with high exposure to arylamines include dye workers, rubber workers, leather workers, truck drivers, painters, and aluminum workers. In recent decades, there has been a steady increase in the incidence of bladder cancer. However, health-care workers are making progress in treatment, and the survival rates are improving.
Although testicular cancer accounts for only 1% of all cancers in men, testicular carcinoma is the most common cancer in men in the 15- to 35-year-old age group. There were 7,920 new testicular cancer cases in 2007 and 380 related deaths. Testicular cancer is four times less common in African-American men than in white men. The risk for development of testicular cancer in a man's lifetime is approximately 1 per 500. Approximately 90% of all testicular tumors manifest as an asymptomatic testicular mass. Once these tumors are detected and treatment is begun, the cure rate can approach 90%, even when the tumor has spread beyond the testicle. Many patients have oligospermia or sperm abnormalities before therapy. Virtually all become oligospermic during chemotherapy with platinum-based agents. Many recover sperm production, however, and can father children, often without the use of cryo-preserved semen. In a population-based study, 70% of patients actually fathered children. Men in whom testicular cancer has been cured have approximately a 2% to 5% cumulative risk of developing a cancer in the opposite testicle during the 25 years after initial diagnosis. The most important prognostic factor has been shown to be early detection by routine physical examination and self-examination. All men should be instructed in testicular self-examination.
Erectile dysfunction (ED) is an extremely common problem. It has been estimated that more than 30 million American men have some degree of ED and that nearly a million new cases can be expected to develop annually. Studies have shown that ED affects not only a man's physical and sexual satisfaction but also his general quality of life, with especially strong links to depression. In the Massachusetts Male Aging Study, 52% of men from 40 to 70 years of age had some degree of ED. Seventeen percent reported minimal dysfunction, 25% reported moderate dysfunction, and 10% reported complete dysfunction. This study also revealed the progressive nature of ED with increasing age. At 40 years of age, 5% of the American male population has complete ED, and at 70 years of age, 15% of the population has complete ED. Sixty-seven percent of men 70 years of age have some degree of ED. As the population continues to age, clinicians will treat more and more male patients for ED in the future.
Structure and Physiology
Cross-sectional and frontal views of the male genitalia are shown in Figure 18-1.
The penis is composed of three elongated, distensible structures: two paired corpora cavernosa and a single corpus spongiosum. The urethra runs through the corpus spongiosum. The penis has
Corpus spongiosum External meatus
Vas deferens Epididymis Testicle
Figure 18-1 Male genitalia. A, Diagram of cross section. B, Diagram of frontal view.
two surfaces, dorsal and ventral (urethral), and consists of the root, the shaft, and the head. The shaft is composed of erectile tissue that, when engorged with blood, produces a firm erection necessary for sexual intercourse. The corpora cavernosa also contain smooth muscle that contracts rhythmically during ejaculation.
On the dorsal aspect of the penis in the midline runs the dorsal vein, with an artery and a nerve on either side. The distal end of the corpus spongiosum expands to form the head, or glans penis. The glans penis covers the end of the corpora cavernosa. The glans has a prominent margin on its dorsal aspect, the corona. A slitlike opening on the tip of the glans is the external meatus of the urethra.
The skin of the penis is smooth, thin, and hairless. At the distal end of the penis, a free fold of skin called the prepuce (foreskin) covers the glans. Secreted mucus and sloughed epithelial cells called smegma collect between the prepuce and the glans, providing a lubricant during sexual intercourse. The prepuce can be retracted to expose the glans as far as the corona. During circumcision, the prepuce is removed.
The root of the penis lies deep to the scrotum, in the perineum. At the root, the corpora cavernosa diverge. Each corpus cavernosum is enveloped in a dense, fibroelastic covering called the tunica albuginea, and these tunicae fuse to form the median septum of the penis. A cross section through the penis is shown in Figure 18-2.
The blood supply to the penis is from the internal pudendal artery, from which the dorsal and deep arteries of the corpora cavernosa are derived. The veins drain into the dorsal vein of the penis. In the flaccid state, the venous channels and arteriovenous anastomoses are widely patent, whereas the arteries are partially constricted.
Erection is a complex hemodynamic and neurophysiologic event. In the flaccid state, the smooth muscles of the penile arteries and sinusoid spaces are contracted. The erectile state begins in the brain and requires relaxation of the smooth muscles of the penis. From the brain center, neural signals are sent to the corpora cavernosa, where synthesis and release of the neurotransmitter nitric oxide occur. Nitric oxide is the primary mediator responsible for endothelial and cavernous smooth muscle relaxation. Nitric oxide activates guanylate cyclase to produce cyclic guanosine monophosphate (cyclic GMP), which decreases intracellular calcium levels, allowing smooth muscle relaxation and an increase in arterial inflow and corporal veno-occlusion in the penis. Venous outflow is decreased because distention of the blood-filled sinusoidal spaces compresses the veins against the inner layer of the rigid tunica albuginea. In the erect state, the arteriovenous channels are closed, and the arteries are widely opened. Muscular pillars are present in the walls of the arteries, veins, and arte-riovenous anastomoses, which aid in occluding the lumina. Phosphodiesterase, predominantly type V in penile tissue, catalyzes the conversion of cyclic GMP to GMP and results in detumescence. There are some new medications that selectively inhibit phosphodiesterase V. These agents enhance the effect of the nitric oxide-mediated increase in cyclic GMP levels and significantly improve erectile function and sexual function in men. The anatomy of erection is illustrated in Figure 18-3.
The urethra extends from the internal urinary meatus of the bladder to the external meatus of the penis. The urethra can be divided into three portions: the prostatic (posterior) portion,
Figure 18-3 Anatomy of erection.
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