The penis is formed of three longitudinal cylinders of erectile tissue, the corpus spongiosum and the two corpora cavernosa. The corpus spongiosum is adherent to the perineal membrane posteriorly, and contains the penile urethra. It is expanded anteriorly as the glans penis, and covered by a fold of skin, the foreskin or prepuce. The scrotum contains, on each side, the testis, epididymus and the contents of the spermatic cord. An indirect inguinal hernia may follow the spermatic cord into the scrotum.
Diseases of the penis include the congenital anomalies of epispadias (urethra opening on the dorsal aspect of the penis), and hypospadias (a proximal ventral opening). Infective urethritis is a common venereal disease and this may be accompanied by epididymo-orchitis and a late onset urethral stricture. The prepuce can be strictured beyond the glans penis (phimosis – figure 57) or proximal to it (paraphimosis); circumcision may be required in their treatment. Circumcision also reduces the incidence of balanitis (infection beneath the foreskin), AIDS and carcinoma of the penis. Prepubertal epididymal cysts contain clear fluid but, after puberty, contain sperm (spermatocele). Fluid may collect within the tunica vainalis, the sac surrounding the testis (hydrocele). Prominence of the pampinform venous plexus of the testis (varicocele) is more common on the left side.
The testes may be absent bilaterally (cryptorchidism), undescended (when sited within the inguinal canal or the posterior abdominal wall) or maldescended (when the testis has emerged from the superficial inguinal ring but resides outside the scrotum). Torsion of the testis is usually of an abnormally developed testis, when it lies horizontal and has an incomplete attachment to the epididymis (producing the clapper bell deformity); the condition is often bilateral.
Tumors of the testis in early life are almost invariably germ cell in origin (seminomas, teratomas). Early diagnosis is essential, as the excellent results of treatment are reduced when the tumor breaches the testicular capsule, extends beyond regional nodes or presents with extralymphatic spread. Presentation is usually with testicular enlargement and loss of testicular sensation: examine the abdomen and image for enlarged para- aortic nodes.
Examination of the penis and scrotum is usually in the lying position. Ask the patient to spread his legs to allow the scrotum to be raised onto the front of the thighs. This can be done by pulling on the inferior scrotal skin, but do not hold the testes during this movement, as it is painful (figure 58). Examine the skin of the posterior as well as the anterior surface of the scrotum. Note the distribution of hair around the pubis and scrotum and any skin abnormality.
Examine the contents of the scrotum one side a time (figure 59). The testis is sensitive to pressure and during gentle palpation observe the subject’s face. Check the oval, vertical orientation of the normal 3 cm adult testis with superior, posterior and inferior epididymis and the vas deferens passing cranially behind the testis from the inferior pole (figure 60a,b).
Figure 59 Anatomy of testes and spermatic cord
1. Middle finger on superficial inguinal ring
2. Spermatic cord
3. Superior pole of epididymis
4. Body of testis
5. Inferior pole of epididymis
The spermatic cord is palpated at the neck of the scrotum, where the contents can be rolled between finger and thumb, and the prominent vas deferens is palpable (figure 61). It is at this site that the vas deferens is manipulated to a subcutaneous position for the operation of vasectomy.
If a scrotal mass is present, first decide whether it is possible to get above it. If not, the inguinoscrotal extension is probably an indirect inguinal hernia. If the mass is confined to the scrotum, check whether the testis can be palpated as a discrete entity or whether it is surrounded by the mass, this is the case in a hydrocele. The latter may be tensely filled with fluid and the testis difficult to palpate. Cysts of the epididymis are usually sited above the testis and can be palpated separate from it, although occasionally they may occur within a hydrocele sac.
The prepubertal testis and epididymis are the same shape as the adult. Note the absence of secondary sexual hair. Testicular size is assessed by comparison with a standard size set of oval beads. Differentiation of cystic and solid structures is aided by transillumination. A varicocele is a collection of varicosities (of the pampiniform plexus), which has been aptly described as a bag of worms.
When examining the penis, note whether the subject has been circumcised. If not, retract the foreskin to ensure there is no underlying lesion and check the normality of the urethral orifice (figure 62). Always replace the retracted foreskin to avoid risk of a paraphimosis.
When examining a patient for venereal disease, observe the meatus for discharge and massage the penile urethra from proximal to distal to express a sample (figure 63a,b).