What is the penis?
The penis is one of the external structures of the male reproductive system. The penis has three parts:
- The root (this part attaches to the wall of the abdomen).
- The body or shaft.
- The glans penis (a cone-shaped end also called the head).
The opening of the urethra, the tube that transports semen and urine out of the body, is located at the tip of the glans penis.
The body of the penis is cylindrical in shape and consists of three internal chambers. These chambers are made up of special, sponge-like erectile tissue. This tissue contains thousands of large caverns that fill with blood when the man is sexually aroused. As the penis fills with blood, it becomes rigid and erect, which allows for penetration during sexual intercourse. The skin of the penis is loose and elastic to accommodate changes in penis size during an erection.
Semen, which contains sperm (the male reproductive cells), is expelled through the end of the penis when the man reaches sexual climax (orgasm). Disorders of the penis can affect a man's sexual functioning and fertility.
What disorders affect the penis?
There are several disorders that can affect the penis. These can include:
The most common form is ischemic priapism, which is a persistent, fully rigid and very painful erection that can last from several hours to a few days. The priapism erection is not associated with sexual activity and is not relieved by orgasm. It happens when blood flows into the penis but is not drained. Common causes of priapism include:
- Alcohol or drug abuse (especially cocaine).
- Certain medications, including some antidepressants and blood pressure medications.
- Spinal cord problems.
- Injury to the genitals.
- Penile injection therapy (a treatment for erectile dysfunction).
- Blood diseases, including leukemia and sickle cell anemia.
Ischemic priapism is an emergency. It is important to get prompt treatment to avoid damage to the penis. In most cases, treatment can involve:
- Draining the blood using a needle placed in the side of the penis.
- Using medications to help shrink the blood vessels, which decreases the blood flow to the penis.
- Using surgery to avoid permanent damage to the penis if these above measures fail.
- Using a blood transfusion in cases when the patient has a condition like sickle cell disease.
Treating any underlying medical condition or substance abuse problem is important in preventing priapism.
High flow or arterial priapism is a persistent erection, which is not rigid and not painful. Unlike ischemic priapism, this does not require urgent treatment. Treatment, when requested by the patient, usually involves a temporary block to a branch of an artery that goes to the penis.
This is a condition in which a plaque (scar tissue) forms in the penis. The plaque may develop on the upper (more common) or lower side of the penis, in the elastic layers that surround erectile tissue. The plaque often begins as a localized area of irritation and swelling (inflammation) and can develop into a hardened scar. The scarring reduces the elasticity of the penis in the area affected.
Peyronie’s disease can result in:
- Painful erections.
- Shortening of the penis.
- Reduced flexibility (due to the plaque).
- Bending or arcing of the penis during an erection.
- Emotional distress, as well as affecting a man’s desire and ability to function during sex.
The exact cause of Peyronie’s disease is unknown. However, evidence links this to injuries that occur during sex in men who have erectile insufficiency (EI) or erectile dysfunction (ED).
Peyronie’s disease is not a disease, but the results of injury. While its impact on a man’s sexual health may be great, treatment is not needed unless a man wants to have penetrative sex and cannot because of erectile deformity or erectile dysfunction.
If the erection needs to be straightened, this can be done by one of two surgical options:
- Removing the plaque and placing new tissue.
- Removing or pinching the tissue from the sides of the penis opposite of the plaque to cancel out the bending effect.
A risk factor of the first option is partial loss of erectile function, especially rigidity. The second procedure, also known as the Nesbit procedure, shortens the normal side of the penis to balance the shortening due to scar on the opposite side. This procedure does not decrease erectile function.
Non-surgical treatment for Peyronie's disease involves injecting medication directly into the plaque in an attempt to:
- Soften the affected tissue.
- Correct the curvature of the penis.
Penile implants can be used in cases where Peyronie's disease has affected the man's ability to achieve or maintain an erection.
This condition is an inflammation (swelling) of the glans (head of) penis. A similar condition, balanoposthitis, refers to inflammation of the head and the foreskin. Symptoms of balanitis include:
- A foul-smelling discharge.
Balanitis most often occurs in men and boys who have not been circumcised (had their foreskin surgically removed), and who have poor hygiene. Inflammation can occur if the sensitive skin under the foreskin is not washed regularly, allowing sweat, debris, dead skin and bacteria to collect under the foreskin and cause irritation. The presence of tight foreskin may make it difficult to keep this area clean and can lead to irritation by a foul-smelling substance (smegma) that can accumulate under the foreskin.
Other causes may include:
- Dermatitis/allergy: Dermatitis is an inflammation of the skin, often caused by an irritating substance or a contact allergy. Sensitivity to chemicals in certain products can cause an allergic reaction, including irritation, itching and a rash. These products can include:
- Infection: Infection with the yeast candida albicans (thrush) can result in an itchy, spotty rash. Certain sexually transmitted diseases can produce symptoms of balanitis. These diseases can include:
In addition, men with diabetes are at greater risk of balanitis. Glucose (sugar) in the urine that is trapped under the foreskin serves as a breeding ground for bacteria.
Persistent inflammation of the penis head and foreskin can result in scarring, which can cause a tightening of the foreskin (phimosis) and a narrowing of the urethra (tube that drains urine from the bladder). Inflammation also can lead to swelling of the foreskin, which can cause injury to the penis.
Treatment for balanitis depends on the underlying cause. If there is an infection, treatment will include an appropriate antibiotic or antifungal medication. In cases of severe or persistent inflammation, a circumcision may be recommended.
Taking appropriate hygiene measures can help prevent future bouts of balanitis. In addition, it is important to avoid strong soaps or chemicals, especially those known to cause a skin reaction.
Ejaculation disorders and erectile dysfunction
Problems with ejaculation are:
- Premature ejaculation (PE): Ejaculation that occurs before or too soon after penetration.
- Inhibited or delayed ejaculation: Ejaculation does not happen or takes a very long time.
- Retrograde ejaculation: At orgasm, the ejaculate is forced back into the bladder rather than through the end of the penis.
The exact cause of premature ejaculation (PE) is not known. While in many cases PE is due to performance anxiety during sex, other factors may be:
- Temporary depression.
- History of sexual repression.
- Low self-confidence.
- Lack of communication or unresolved conflict with a partner.
Studies suggest that the breakdown of serotonin (a natural chemical that affects mood) may play a role in PE. Certain drugs, including some antidepressants, may affect ejaculation, as can nerve damage to the back or spinal cord.
Physical causes for inhibited or delayed ejaculation may include:
- Chronic (long-term) health problems.
- Medication side effects.
- Alcohol abuse.
- Psychological factors.
Retrograde ejaculation is most common in males with diabetes who suffer from diabetic nerve damage. Problems with the nerves in the bladder and the bladder neck force the ejaculate to flow backward. In other men, retrograde ejaculation may be a side effect of some medications or happen after an operation on the bladder neck or prostate.
Erectile dysfunction (ED) is the inability to get and keep an erection for sexual intercourse. ED is quite common, with studies showing that about one-half of American men over age 40 are affected. Causes of ED include:
- Diseases affecting blood flow, such as hardening of the arteries.
- Nerve disorders.
- Stress, relationship conflicts, depression and performance anxiety.
- Injury to the penis.
- Chronic illness such as diabetes and high blood pressure.
- Unhealthy habits.
Phimosis and paraphimosis
Phimosis is a condition in which the foreskin of the penis is so tight that it cannot be pulled back (retracted) to reveal the head of the penis. Paraphimosis occurs when the foreskin, once retracted, cannot return to its original location.
Phimosis, which is seen most often in children, may be present at birth. It also can be caused by:
- An infection.
- Scar tissue that formed from an injury or chronic inflammation.
- Posthitis (a condition that leads to scarring and tightness of the foreskin).
Immediate medical attention is necessary if the condition makes urination difficult or impossible.
Paraphimosis is a medical emergency that can cause serious complications if not treated. Paraphimosis may happen after an erection or sexual activity, or as the result of injury to the head of the penis. With paraphimosis, the foreskin becomes stuck behind the ridge of the head of the penis. If this condition is prolonged, it can cause:
- Impaired blood flow to the penis.
In extreme cases, the lack of blood flow can result in the death of tissue (gangrene), and amputation of the penis may be necessary.
Treatment of phimosis may include gentle, manual stretching of the foreskin over a period of time. Sometimes, the foreskin can be loosened with medication applied to the penis. Circumcision, the surgical removal of the foreskin, often is used to treat phimosis. Another surgical procedure, called preputioplasty, involves separating the foreskin from the glans. This procedure preserves the foreskin and is less traumatic than circumcision.
Treatment of paraphimosis focuses on reducing the swelling of the glans and foreskin. Applying ice may help reduce swelling, as may applying pressure to the glans to force out blood and fluid. If these measures fail to reduce swelling and allow the foreskin to return to its normal position, an injection of medication to help drain the penis may be necessary. In severe cases, a surgeon may make small cuts in the foreskin to release it. Circumcision also may be used as a treatment for paraphimosis.
A rare form of cancer, penile cancer occurs when abnormal cells in the penis divide and grow uncontrolled. Certain benign (non-cancerous) tumors may progress and become cancer.
The exact cause of penile cancer is not known, but there are certain risk factors for the disease. A risk factor is anything that increases a person's chance of getting a disease. The risk factors for cancer of the penis may include the following:
- Circumcision: Men who are not circumcised at birth have a higher risk of getting cancer of the penis.
- Human papilloma virus (HPV): HPVs are a group of more than 70 types of viruses that can cause warts (papillomas). Certain types of HPVs can infect the reproductive organs and the anal area. These types of HPVs are passed from one person to another during sexual contact.
- Smoking: Smoking exposes the body to many cancer-causing chemicals that affect more than the lungs.
- Smegma: Oily secretions from the skin can accumulate under the foreskin of the penis. The result is a thick, bad-smelling substance called smegma. If the penis is not cleaned thoroughly, the presence of smegma can cause irritation and inflammation.
- Phimosis: This is a condition in which the foreskin becomes constricted and difficult to retract.
- Treatment for psoriasis: The skin disease psoriasis is sometimes treated with a combination of medication and exposure to ultraviolet light.
- Age: Most cases of penile cancer occur in men over age 50.
Symptoms of penile cancer include growths or sores on the penis, abnormal discharge from the penis and bleeding. Surgery to remove the cancer is the most common treatment for penile cancer. A doctor may take out the cancer using one of the following operations:
- Wide local excision takes out only the cancer and some normal tissue on either side.
- Microsurgery is an operation that removes the cancer and as little normal tissue as possible. During this surgery, the doctor uses a microscope to look at the cancerous area to make sure all the cancer cells are removed.
- Laser surgery uses a narrow beam of light to remove cancer cells.
- Circumcision is an operation that removes the foreskin.
- Amputation of the penis (penectomy) is an operation that removes the penis. In a partial penectomy, part of the penis is removed. In a total penectomy, the whole penis is removed. Lymph nodes in the groin may be taken out during surgery.
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