(See also Overview of Infertility Overview of Infertility Infertility is usually defined as the inability of a couple to achieve a pregnancy after repeated intercourse without contraception for 1 year. Frequent intercourse without birth control usually... read more .)
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 Undescended Testes and Retractile Testes Undescended testes (cryptorchidism) are testes that remain in the abdomen or the groin instead of descending into the scrotum. Retractile testes (hypermobile testes) have descended into the... read more and varicose veins (called a varicocele Scrotal Swelling Swelling of the scrotum (the sac that surrounds and protects the testes) on one or both sides may be a symptom of a urinary tract disorder. Swelling can be small and detectable only by carefully... read more ), increase the temperature of these organs. Effects of excessive or prolonged heat can last up to 3 months.
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 Anabolic Steroids Anabolic steroids are synthetic (man-made) versions of testosterone that are used to increase muscle size. Anabolic steroids are hormones that promote muscle growth and increase strength and... read more , 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 Problems With Ovulation The ovaries do not release an egg each month, as usually occurs during a menstrual cycle. Ovulation problems can result from dysfunction of the part of the brain and the glands that control... read more (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 Diabetes Mellitus (DM) Diabetes mellitus is a disorder in which the body does not produce enough or respond normally to insulin, causing blood sugar (glucose) levels to be abnormally high. Urination and thirst are... read more , multiple sclerosis, brain or nerve disorders (including Alzheimer disease Alzheimer Disease Alzheimer disease is a progressive loss of mental function, characterized by degeneration of brain tissue, including loss of nerve cells, the accumulation of an abnormal protein called beta-amyloid... read more , Parkinson disease Parkinson Disease (PD) Parkinson disease is a slowly progressive degenerative disorder of specific areas of the brain. It is characterized by tremor when muscles are at rest (resting tremor), increased muscle tone... read more , stroke Ischemic Stroke An ischemic stroke is death of an area of brain tissue (cerebral infarction) resulting from an inadequate supply of blood and oxygen to the brain due to blockage of an artery. Ischemic stroke... read more , certain seizure disorders Seizure Disorders In seizure disorders, the brain's electrical activity is periodically disturbed, resulting in some degree of temporary brain dysfunction. Many people have unusual sensations just before a seizure... read more , 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.
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 Structure of the Male Reproductive System The male reproductive system includes the penis, scrotum, testes, epididymis, vas deferens, prostate, and seminal vesicles. The penis and the urethra are part of the urinary and reproductive... read more : blocked or missing vasa deferentia, missing seminal vesicles, and blockage of both ejaculatory ducts
The same genetic abnormality that causes cystic fibrosis Cystic Fibrosis (CF) Cystic fibrosis is a hereditary disease that causes certain glands to produce abnormally thick secretions, resulting in tissue and organ damage, especially in the lungs and the digestive tract... read more 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 Retrograde Ejaculation Retrograde ejaculation is a condition in which semen is ejaculated backward into the bladder rather than out through the penis. (See also Overview of Sexual Dysfunction in Men.) In retrograde... read more .
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.
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 Polymerase chain reaction (PCR) Genetic diagnostic technologies are scientific methods that are used to understand and evaluate an organism's genes. (See also Genes and Chromosomes.) Genes are segments of deoxyribonucleic... read more (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.
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 Clomiphene The ovaries do not release an egg each month, as usually occurs during a menstrual cycle. Ovulation problems can result from dysfunction of the part of the brain and the glands that control... read more , 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.
If sperm count is low or if clomiphene is ineffective, the most effective treatment is usually in vitro fertilization In vitro (test tube) fertilization (IVF) Assisted reproductive techniques involve manipulating sperm and eggs or embryos in a laboratory (in vitro) with the goal of producing a pregnancy. (See also Overview of Infertility.) If treatment... read more , often with intracytoplasmic sperm injection Intracytoplasmic sperm injection Assisted reproductive techniques involve manipulating sperm and eggs or embryos in a laboratory (in vitro) with the goal of producing a pregnancy. (See also Overview of Infertility.) If treatment... read more (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 The ovaries do not release an egg each month, as usually occurs during a menstrual cycle. Ovulation problems can result from dysfunction of the part of the brain and the glands that control... read more 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.