Male Genitalia

Anatomy And Physiology

The penis, testicles, epididymides, scrotum, prostate gland, and seminal vesicles constitute the male genitalia ( Fig. 20.1 ).

The penis serves as the final excretory organ for urine and, when erect, as the means of introducing semen into the vagina. The penis consists of the corpora cavernosa, which form the dorsum and sides, and the corpus spongiosum, which contains the urethra. The corpus spongiosum expands at its distal end to form the glans penis. The urethral orifice is a slitlike opening located approximately 2 mm ventral to the tip of the glans ( Figs. 20.2 and 20.3 ). The skin of the penis is thin, redundant to permit erection, and free of subcutaneous fat. It is generally more darkly pigmented than body skin. Unless the patient has been circumcised, the prepuce (foreskin) covers the glans. In the uncircumcised penis, smegma is formed by the secretion of sebaceous material by the glans and the desquamation of epithelial cells from the prepuce. It appears as a cheesy white material on the glans and in the fornix of the foreskin.

The scrotum, like the penis, is generally more darkly pigmented than body skin. A septum divides the scrotum into two pendulous sacs, each containing a testis, epididymis, spermatic cord, and a muscle layer termed the cremasteric muscle that allows the scrotum to relax or contract ( Fig. 20.4 ). Testicular temperature is controlled by altering the distance of the testes from the body through muscular action. Spermatogenesis requires maintenance of temperatures lower than 37 °C.

The testicles are responsible for the production of both spermatozoa and testosterone. The adult testis is ovoid and measures approximately 4×3×2 cm. The epididymis is a soft, comma-shaped structure located on the posterolateral and upper aspect of the testis. It provides for storage, maturation, and transit of sperm. The vas deferens begins at the tail of the epididymis, ascends the spermatic cord, travels through the inguinal canal, and unites with the seminal vesicle to form the ejaculatory duct.

The prostate gland, which resembles a large chestnut and is approximately the size of a testis, surrounds the urethra at the bladder neck. It produces the major volume of ejaculatory fluid, which contains fibrinolysin. This enzyme liquefies the coagulated semen, a process that may be important for satisfactory sperm motility. The seminal vesicles extend from the prostate onto the posterior surface of the bladder.

Erection of the penis occurs when the two corpora cavernosa become engorged with blood, generally 20 to 50 mL. Arterial dilation and decreased venous outflow pro duce the increased blood supply; both processes are under the control of the autonomic nervous system and occur because of the local synthesis of nitric oxide. Ejaculation during orgasm consists of the emission of secretions from the vas deferens, epididymides, prostate, and seminal vesicles. Orgasm is followed by constriction of the vessels supplying blood to the corpora cavernosa and gradual detumescence (subsidence of the erection).

Review of Related History

For each of the symptoms or conditions discussed in this section, targeted topics to include in the history of the present illness are listed. Responses to questions about these topics provide clues for focusing the physical examination and the development of an appropriate diagnostic evaluation. Questions regarding medication use (prescription and over-the-counter preparations) as well as complementary and alternative therapies are relevant for each.

History of Present Illness

Past Medical History

• Gender identity: e.g., male, female, non-binary, transgender woman, transgender man; sex assignment at birth

• Organ inventory: penis (natal or surgically constructed), scrotum and testicles (natal or surgically constructed), prostate gland, clitoris (natal or surgically constructed), vagina (natal or surgically constructed), cervix, uterus, fallopian tubes, ovaries

• Congenital anomaly and/or surgery of genitourinary tract: undescended testes, hypospadias, epispadias, hydrocele, varicocele, hernia, prostate; vasectomy

• STIs: single or multiple infections, specific organism (gonorrhea, syphilis, herpes, human papillomavirus [HPV]), chlamydia), treatment, effectiveness, residual problems; vaccination for HPV (see Patient Safety Box; HPV Immunization)

• Chronic illness: testicular or prostatic cancer, neurologic or vascular impairment, diabetes mellitus, cardiac Disease

• Recent and past genitourinary/gynecologic procedures: masculinizing phalloplasty, scrotoplasty, erectile implants, vaginectomy, metoidioplasty (clitoral release/enlargement that may include urethral lengthening), hysterectomy, oophorectomy, orchiectomy, feminizing vaginoplasty

Family History

• Infertility in siblings

• History of prostate, testicular, penile or breast cancer

• Hernias

• Peyronie Disease (contracture of penis)

Personal and Social History

• Occupational risk of trauma to suprapubic region or genitalia, exposure to radiation or toxins

• Exercise: use of a protective device with contact sports or bicycle riding

• Concerns about genitalia: size, shape, surface characteristics, texture

• Testicular/genital self-examination practices (see Patient Safety, “Self-Examination for STIs”)

• Concerns about sexual behaviors including sexual partners (single or multiple)

• Concerns about sexual orientation (heterosexual, homosexual, bisexual), or gender identity (transgender, cisgender, agender)

• Reproductive function: number of children, form of contraception used, frequency of ejaculation

• Alcohol, marijuana use: quantity and frequency

• Use of drugs

Infants and Children

• Maternal use of sex hormones or birth control pills during pregnancy

• Circumcised: complications from procedure

• Uncircumcised: hygiene measures, retractability of foreskin, interference with urinary stream

• Scrotal swelling with crying or bowel movement

• Congenital anomalies: hypospadias, epispadias, undescended testes, ambiguous genitalia

• Parental concerns with masturbation, sexual exploration

• Swelling, discoloration, or sores on the penis or scrotum, pain in the genitalia

• Concern for sexual abuse

Adolescents

• Knowledge of reproductive function, source of information about sexual activity and function

• Presence of nocturnal emissions, pubic hair, enlargement of genitalia, age at time of each occurrence and of first nocturnal emissions

• Concern of sexual abuse

• Sexual activity, protection used for contraception and STI prevention

Older Adults

• Change in frequency of sexual activity or desire: related to loss of spouse or other sexual partner; no sexual partner; sexually restrictive environment; depression; physical illness resulting in fatigue, weakness, or pain.

• Change in sexual response: longer time required or inability to achieve full erection, less forceful ejaculation, more rapid detumescence, longer interval between erections, prostate surgery.

Patient Safety

Self-Examination to Detect STIs

Genital self-examination (GSE) is recommended for anyone who is at risk for contracting a sexually transmitted infection (STI). This includes sexually active persons who have had more than one sexual partner or whose partner has had other partners. The purpose of GSE is to detect any signs or symptoms that might indicate the presence of an STI. Many people who have an STI do not know they have one, and some STIs can remain undetected for years. GSE should become a part of routine self-examination healthcare practices. Explain and demonstrate the following procedure to your patients and give them the opportunity to perform a GSE with your guidance.

Instruct the patient to hold the penis in the hand and examine the head. If not circumcised, the patient should gently pull back the foreskin to expose the glans. Inspection and palpation of the entire head of the penis should be performed in a clockwise motion while the patient carefully looks for any bumps, sores, or blisters on the skin. Bumps and blisters may be red or light-colored or may resemble pimples. Have the patient also look for genital warts, which may look similar to warts on other parts of the body. The urethral meatus should also be examined for any discharge.

Next, the patient will examine the entire shaft and look for the same signs. Instruct the patient to separate the pubic hair at the base of the penis and carefully examine the skin underneath. Be sure to include the underside of the shaft in the examination; a mirror may be helpful.

Instruct the patient to examine the scrotal skin and contents; hold each testicle gently and inspect and palpate the skin, including the underneath of the scrotum, looking for any lesions, lump, swelling, or soreness. Educate the patient about other symptoms associated with STIs, specifically pain or burning on urination or discharge from the penis. The discharge may vary in color, consistency, and amount.

Any of the preceding signs or symptoms require evaluation by a healthcare provider.

From American Cancer Society (2018) ; ASCO, (2019); and Deutsch (2016) .

Risk Factors

Cancer of the Male Genitalia

Penile

• Infection with high-risk types of HPV

• Lack of circumcision with failure to maintain good hygiene

• Phimosis

• Age: risk increases with age

• Smoking (smoking alone increases risk; smokers with HPV infection at even higher risk)

• HIV infection

• UV light treatment of psoriasis if genitalia exposed

Testicular

• Undescended testicle (cryptorchidism): risk elevated for both testicles

• Personal history of testicular cancer (the opposite testicle is at increased risk)

• Family history of testicular cancer

• HIV infection

• Age: 20–34 years

• Race: White; five times greater than that of Blacks and more than three times that of Asian Americans and Native Americans

• Androgen suppression: likely decreases the risk in transgender women