Sperm may be too few in number, move too slowly, or be structurally abnormal, or their passage out of the body may be blocked or disrupted.
- An increase in the testes’ temperature, certain disorders, injuries, and some drugs and toxins can cause problems with sperm.
- Semen is analyzed, and sometimes genetic tests are done.
- Clomiphene, a fertility drug, may increase the number of sperm, but assisted reproductive techniques may be needed.
(See also Overview of Infertility.)
To be fertile, a man must be able to deliver an adequate quantity of normal sperm to a woman’s vagina, and sperm must be able to fertilize the egg. Conditions that interfere with this process can make a man less fertile.
Conditions that increase the temperature of the testes (where sperm are produced) can greatly reduce the number of sperm and the vigor of sperm movement and can increase the number of abnormal sperm. Some disorders of the testes, such as undescended testes and varicose veins (called a varicocele), increase the temperature of these organs. Effects of excessive or prolonged heat can last up to 3 months.
What Causes Infertility in Men?
Reduced sperm production
Increased temperature of the testes
Disorders that cause a prolonged fever
Adrenal gland disorders (this gland produces testosterone and other hormones)
Hyperprolactinemia (high levels of prolactin, a hormone that stimulates milk production)
Hypogonadism (low levels of testosterone and/or impaired production of sperm), sometimes related to obesity
Hypothalamic disorders (the hypothalamus is the part of the brain that controls the pituitary gland, which controls testosterone production)
Other disorders that cause an abnormality in the sex chromosomes
Disorders of the testes
Injury to the testes
Mumps that affects the testes (mumps orchitis)
Shrinking of the testes (as can occur when excess alcohol is regularly consumed)
Tumors in the testes
Undescended testes (testes that remain in the abdomen rather than move to the scrotum)
Varicose veins in the testes (varicocele)
Alcohol, when consumed in large amounts
Androgens (male hormones such as testosterone)
Antiandrogens (drugs that counteract the effects of androgens, such as bicalutamide, cyproterone, and flutamide)
Aspirin when taken for a long time
Caffeine when consumed in excessive amounts (possibly)
Chlorambucil (a chemotherapy drug)
Cimetidine (used to treat stomach ulcers)
Colchicine (used to treat gout)
Corticosteroids taken by mouth (such as prednisone)
Cotrimoxazole (an antibiotic)
Cyclophosphamide (a chemotherapy drug)
Drugs used to treat malaria
Estrogens taken to treat prostate cancer
Gonadotropin-releasing hormone (GnRH) agonists (hormonal drugs used to treat prostate cancer, fibroids, endometriosis, and other disorders)
Medroxyprogesterone (a synthetic female hormone)
Methotrexate (a drug that suppresses the immune system)
Monoamine oxidase inhibitors (MAOIs—a type of antidepressant)
Nitrofurantoin (an antibiotic)
Spironolactone (a diuretic)
Sulfasalazine (an antibiotic sometimes used to treat inflammatory bowel disease)
Exposure to industrial or environmental toxins
Heavy metals, such as lead
Pesticides (which can have effects similar to those of female hormones or decrease the effects of male hormones)
Phthalates (chemicals used to make plastics more flexible)
Polychlorinated biphenyl compounds (PCBs)
Absence of sperm in semen
Disruption of the sperm’s passage out of the body
Missing epididymides (which provide the space and environment for sperm to mature), usually in men with cystic fibrosis
Blocked or missing vasa deferentia (tubes from the epididymides to the ejaculatory ducts), usually in men with cystic fibrosis
Missing seminal vesicles (which provide nourishment for sperm)
Blockage of both ejaculatory ducts
Retrograde ejaculation (semen travels back into the bladder rather than out of the penis)
Nervous system dysfunction
Pelvic surgery, such as prostate removal
Removal of lymph nodes in the area behind the abdomen (as may be done to treat Hodgkin lymphoma)
Erectile dysfunction (the inability to attain or maintain an erection sufficient for sexual intercourse)
Blood vessel disorders
Brain and nerve (neurologic) disorders, such as Alzheimer or Parkinson disease, multiple sclerosis, stroke, and nerve damage due to prostate surgery
Psychologic problems, such as performance anxiety or depression
Certain drugs, such as some antidepressants, certain hormonal drugs, and drugs used to treat high blood pressure (including beta-blockers)
Recreational drugs (such as cocaine, heroin, and amphetamines)
Unknown causes (idiopathic)
Certain hormonal or genetic disorders may interfere with sperm production, as can other disorders.
Exposure to industrial or environmental toxins and use of certain drugs can reduce sperm production. Taking anabolic steroids, such as testosterone and other synthetic male hormones (androgens), lowers production of the pituitary gland hormones that stimulate sperm production and can thus decrease sperm production. They can also cause the testes to shrink.
Erectile dysfunction (the inability to attain or maintain an erection sufficient for sexual intercourse) can cause infertility in men. It may result from a disorder, such as a blood vessel disorder, diabetes, multiple sclerosis, brain or nerve disorders (including Alzheimer disease, Parkinson disease, stroke, certain seizure disorders, and nerve damage due to prostate surgery), use of certain drugs (including some antidepressants and beta-blockers), use of recreational drugs (including cocaine, heroin, and amphetamines), or psychologic problems (including performance anxiety or depression). Erectile dysfunction may be the first clue that a man has a blood vessel disorder such as atherosclerosis.
Did You Know...
Some disorders result in the complete absence of sperm (azoospermia) in semen. They include
- Serious disorders of the testes
- Disorders of other parts of the male reproductive system: blocked or missing vasa deferentia, missing seminal vesicles, and blockage of both ejaculatory ducts
The same genetic abnormality that causes cystic fibrosis can cause azoospermia, often by preventing both vasa deferentia from forming.
Azoospermia can also occur if semen, which contains the sperm, moves in the wrong direction (into the bladder instead of down the penis). This disorder is called retrograde ejaculation.
Locating the Male Reproductive Organs
- A doctor's evaluation
- A semen analysis
- Sometimes testing for hormonal or genetic abnormalities
When couples are infertile, the man is always evaluated for sperm disorders. Doctors ask the man about his medical history and do a physical examination to try to identify the cause. Doctors ask about past disorders and surgery, use of drugs, and possible exposure to toxins. They check for physical abnormalities, such as undescended testes, and for signs of hormonal or genetic disorders that can cause infertility. Levels of hormones (including testosterone) may be measured in the blood.
A semen analysis, the main screening procedure for male infertility, is needed. For this procedure, men are often asked not to ejaculate for 2 to 3 days before the analysis. The reason is to make sure the semen contains as many sperm as possible. Then they are asked to ejaculate by masturbation into a sterile jar, preferably at the laboratory site. For men who have difficulty producing a semen sample this way, special condoms that have no lubricants or chemicals toxic to sperm can be used to collect semen during intercourse.
Because the number of sperm varies, the test requires at least two samples obtained at least 1 week apart. When several samples are tested, results are more accurate than when only one is tested.
The volume of the semen sample is measured. Whether the color, consistency, thickness, and chemical composition of semen are normal is determined. The sperm are counted. A low sperm count may mean that fertility is reduced, but not always. Sperm are also examined under a microscope to determine whether they are abnormal in shape, size, or movement.
If the semen still seems to be abnormal, the doctor tries to identify the cause. If there are too few or no sperm, doctors measure levels of certain hormones, such as testosterone and follicle-stimulating hormone (which stimulates production of sperm in men), and genetic testing may be done. Also, urine may be checked for sperm after ejaculation to determine whether retrograde ejaculation is occurring.
Sometimes a biopsy of the testes is done to help identify the cause of infertility.
Other tests, which use a sample of blood or semen, can be done to evaluate sperm function and quality if routine tests of both partners do not explain infertility. These tests may check for antibodies to sperm, determine whether sperm membranes are intact, or assess the sperm's ability to bind to an egg and penetrate it. However, how useful these tests are is unclear.
Hormone tests are done if results of semen analysis are abnormal, especially if the sperm count is very low. Levels of follicle-stimulating hormone (which stimulates the testes to produce sperm) and testosterone are measured. If the testosterone level is low, luteinizing hormone (which stimulates the testes to produce testosterone) and prolactin (which stimulates milk production in men and women) are measured. A high level of prolactin suggests that the cause of infertility may be a pituitary tumor or use of certain drugs.
Genetic testing is done if doctors determine that there are too few or no sperm. For genetic tests, almost any tissue, including blood, can be used. Tests include chromosome analysis (called karyotyping). The polymerase chain reaction (PCR) may to used to produce many copies of a gene or segments of a gene, which makes studying the gene much easier. Doctors check for the gene that causes cystic fibrosis. Before a man with this gene mutation and his partner attempt to conceive, the partner should also be tested for the gene.
- Treatment of the cause
- Clomiphene (a fertility drug)
- If clomiphene is ineffective, assisted reproductive techniques
If possible, the disorder causing the problem is treated. For example, varicoceles can be treated with surgery. Fertility may improve as a result, although this effect has not been proved.
Clomiphene, a drug used to stimulate (induce) ovulation in women, may be used to try to increase sperm counts in men. However, whether clomiphene improves the sperm’s ability to move or reduces the number of abnormal sperm is unclear. It has not been proved to increase fertility.
Assisted reproductive techniques
If sperm count is low or if clomiphene is ineffective, the most effective treatment is usually in vitro fertilization, often with intracytoplasmic sperm injection (the injection of one sperm into one egg)—an assisted reproductive technique.
An alternative is intrauterine insemination (placing semen directly in the uterus) using only the most active sperm. The most active sperm are selected by washing a semen sample. Doctors try to place these sperm in the uterus at the same time as ovulation. With this procedure, pregnancy usually occurs by the sixth attempt if it is going to occur. Intrauterine insemination is far less effective than in vitro fertilization but is much less invasive and less expensive.
Doctors can sometimes identify and retrieve a few sperm for intracytoplasmic sperm injection by doing a biopsy and examining the sample with a microscope to find the sperm. If no sperm are found, inseminating the woman with sperm from another man (a donor) may be considered. Because of the danger of contracting sexually transmitted diseases, including infection with human immunodeficiency virus (HIV) and hepatitis C, fresh semen samples from donors are no longer used in the United States. Risk of disease transmission is minimized by freezing donor sperm for 6 months or more, then retesting donors for infection. If their test results remain negative, the sample is thawed and used. Semen collection is postponed for 3 months if donors have been infected with the Zika virus or if donors have lived in or traveled to an area where the Zika virus is being transmitted.
The partner of a man who has fertility problems may be treated with human gonadotropins to stimulate several eggs to mature and be released while in vitro fertilization or intrauterine insemination is being tried. This approach may make pregnancy more likely.
Drugs Mentioned In This Article
|Generic Name||Select Brand Names|
|Nitrofurantoin||FURADANTIN, MACROBID, MACRODANTIN|
|cyproterone||No US brand name|