In the adult male, the external portion of the penis is about 2-3 inches long in the non-erect state. When it is cold, the penis can withdraw into fatty tissue overlying the pubic bone, which makes it seem shorter. There is generally little variation in the "real" length of the penis among different men. In some races its somewhat longer and in others a bit shorter. During erection, the penile length varies. The penis has three functions: urination, sexuality and reproduction. Three major structures can be found in the penis: the urethra and two long cylinders, the erectile bodies, known as the corpora cavernosa. Unlike the lower urinary tract in women in which the urethra is fairly short, the male urethra is much longer as it exits through the penis. Because of this, the penis is considered part of the urogenital system.
As with organs higher in the urogenital tract, diseases of the penis often have to do with obstruction, infection, and cancer. In addition, because of its dual role in both the urinary reproductive tracts, urologists also treat disorders of sexual function.
Initial evaluation of a patient may include, examination of the urine or blood , ultrasound or neurologic testing. If blockage is suspected, visual inspection of the urethra with a scope may be performed.
Infections of the urethra are most often treated with antibiotics, but abscesses may need surgery. If scar tissue forms in the urethra and causes blockage, it may need to be surgically excised.
The foreskin of an uncircumcised penis is normally, very elastic and can be retracted easily to reveal the glans (end of the penis). If the foreskin becomes infected, it can shrink to such an extent that it can become difficult to urinate. A foreskin that cannot be easily retracted is often seen in young boys and often corrects itself. When retraction of the foreskin is not possible, the glans underneath cannot be cleaned properly and may become infected. During erections the glans should automatically show itself. If that is not possible, erection may be painful and require medical attention. This condition is called Phimosis.
Cancer of the penis is rare in the United States because of hygiene and because circumcisions (removal of the foreskin) is commonly performed soon after birth for males widespread. Rarely a tumor starts as a sort of wart on the glans or the foreskin. As a rule, it tends to grow and spread relatively slowly. Unfortunately, it is often found in elderly men who also have a narrowing of the foreskin, or phimosis, thus hiding the underlying cancer. This cancer can sometimes be treated with radiation, but most often is treated surgically.
Peyronie's disease is a result of plaque formation in the penis that occurs outside the urethra and can produce curvature in an erect penis. The plagued erectile body is thus somewhat shorter during erection and pulls the penis into a curve. A slight curvature is not much of a problem but some curvatures make it impossible to have intercourse. This can be treated medically in some cases and surgically in others.
Problems with erections can result from psychological problems, neurologic disease, post-surgical changes, hormonal abnormalities, and diseases of the blood vessels. There was a time when it was thought that most erectile dysfunctions were the result of psychological problems, but is now believed that these are causative in only 10-20% of cases. Many physical and medical disorders impact erectile functions. Narrowing of the block vessels that supply blood to the penis, can decrease the amount of blood flowing toward the erectile bodies during erection causing weakness or absence of an erection. Sometimes the nerves that control erections do not function properly. There is quite a bit of research being done today on erectile dysfunction and the numbers and types of therapies are ever increasing. These range from oral medications to injectable therapy to surgical therapy.
Priapism is a prolonged and painful erection that may last form a few hours to several days. This erection is not associated with erotic thoughts or sexual activity. In most cases of priapism is caused by either medication or systemic disease. Penile injections used to treat some forms of impotence may cause priapism. Some psychiatric medications, certain forms of leukemia, and sickle cell anemia may also cause priapism. Medical help should be sought if the erection continues for longer than four hours.