Causes of Infertility: Male
Author: Dr. Anna Kaplan
The causes of infertility, or the inability of a couple to get pregnant, are split between male problems, female problems, and infertility for unknown reasons. Generally speaking, 24% of infertility is due to “male factors.” Approximately 48% is due to “female factors,” and 28% of infertility is unexplained.
In men, anything that affects the number and quality of sperm can cause infertility. In about half the cases, the reasons are unknown. 30 to 40% of men have what is called primary hypogonadism. This is also called testicular failure, meaning the testicles are not making enough good-quality sperm.
Causes of testicular dysfunction or failure (primary hypogonadism) can include:
- Androgen (male hormone) insensitivity. This means that the testicles are not sensitive to testosterone.
- Congenital or developmental testicular disorder. There are a number of syndromes in which there are genetic or chromosomal abnormalities leading to abnormal genitals. Abnormalities of the Y (or male) chromosome can also cause infertility.
- Undescended testicles. The testicles are supposed to migrate out of the abdomen into their normal position in the scrotum before a baby boy is born. If a testicle stays inside the abdomen, it can become cancerous, as well as less able to produce sperm. All boys with testicles that do not descend on their own should have this problem surgically corrected.
- Medications. Drugs that can decrease the number of sperm or their quality include agents used to treat cancer in general, anti-androgens (usually used to treat male cancer, like prostate cancer), cimetidine (brand name Tagamet, used for ulcers), ketoconazole (brand name Nizoral, used to treat fungal infections), and spironolactone (brand name Aldactone, used to treat high blood pressure).
- Infection of the testicles, also called orchitis. Mumps orchitis is the most common infection.
- Radiation. Excess radiation from any source can cause infertility.
- Systemic diseases. Serious illnesses can cause decreased amounts of normal sperm.
- Testicular trauma. Severe trauma to one or both testicles can result in lowered sperm production.
- Varicocele. This is a collection of varicose veins in the scrotum, which can lower the sperm count.
10 to 20 percent of male infertility occurs because of altered sperm transport, meaning the sperm can’t get where they need to go. Sperm are made in the testicles, stored and somewhat matured in the epididymis, transported from the epididymis to the urethra via the vas deferens, and then go out the urethra along with fluid from the prostate and seminal glands during ejaculation. Some reasons for altered transport include:
- Absent vas deferens or obstruction in the vas deferens. The sperm can’t get to the urethra.
- Epididymal absence or obstruction. This can prevent the sperm from getting to the vas deferens.
- Erectile dysfunction for whatever reason. This can be caused by, among other things, medications, excessive alcohol intake, or neurologic and circulatory problems.
- Retrograde ejaculation. This occurs when the man’s ejaculate goes up the urethra instead of down and out. There are medications that cause this problem.
Secondary hypogonadism means that the testicles are not functioning because of something outside of the male reproductive system. A part of the brain called the hypothalamus as well as the pituitary gland may not work properly. This can occur in 1 to 2 percent of male infertility. Excessively high levels of male hormones taken into the body can tell the brain to stop normal hormone development and normal testicular function. This can happen when athletes take steroids. Other medications, tumors, and trauma can affect the pituitary gland in the brain and prevent the right signals from going to the reproductive system.
When investigating infertility, a doctor will examine the male partner to determine which if any of these problems could be causing the couple’s infertility. Some of these conditions are easy to diagnose and treat; some are not.