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Sperm analysis
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Semen Analysis
Este artigo foi revisto pela última vez em
Este artigo foi modificado pela última vez em 10 de Julho de 2017.
At a Glance
Why Get Tested?
To learn about the health of your reproductive organs, particularly if your partner is having trouble becoming pregnant, or after a vasectomy to determine if the operation was successful
When To Get Tested?
When you think you might have a fertility problem or after you have had a vasectomy
Sample Required?
A semen sample collected in a sterile, wide-mouth container provided by the lab
Test Preparation Needed?
Follow carefully instructions that are provided to you for sample collection.
What is being tested?
A semen analysis measures the quantity and quality of both the liquid portion, called semen, and the microscopic, moving cells, called sperm.

Semen is the turbid, whitish substance that is released from the penis during ejaculation. Sperm are the cells in semen with a head and a tail that enables them to travel to the egg. A sperm contains one copy of each chromosome (all of the male’s genes) and fuses with the female’s egg, resulting in fertilization.

A typical semen analysis measures:

  • the volume of semen,
  • the semen consistency (thickness),
  • sperm concentration,
  • total number of sperm,
  • sperm motility (percent able to move as well as how vigorously and straight the sperm move),
  • the number of normal and not normal (defective) sperm,
  • coagulation and liquefaction,
  • fructose (a sugar in semen),
  • pH (acidity),
  • the number of immature sperm, and
  • the number of white blood cells (cells that indicate infection).

Additional tests may be performed if semen is abnormal, such as a test for sperm antibodies. If assisted reproductive technology is contemplated (for example, in vitro fertilization), sperm function tests may also be performed. Sometimes a test called cryosurvival is done to see how well semen will survive for long-term storage, if a couple would like to store sperm for future pregnancies.

How is the sample collected for testing?

Most labs require samples to be collected on-site as the semen needs to be examined within one hour after ejaculation. Semen is collected in a private area, usually a bathroom. The man masturbates and collects the semen in a jar. Some men, for religious or other reasons, might want to collect semen during the act of intercourse, using a condom. If this is the case, the doctor should provide the condom or sheath because lubricated condoms can affect test results. Sperm are very temperature-sensitive. If collection is done at home, the sample should be kept at room temperature (70°F/21°C) at all times. Never refrigerate the sample or try to warm it to body temperature.

Is any test preparation needed to ensure the quality of the sample?

To give sperm a chance to replenish, a man should abstain from ejaculating for two to four days before the sample is collected. Follow the instructions that are provided to you.
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Common Questions
  • How is it used?
    A semen analysis is used to determine whether a man might be infertile—unable to get a woman pregnant. The semen analysis has many parts and test a lot of aspects of the semen and sperm. A semen analysis to determine fertility should be performed on a minimum of two samples at least seven days apart over a period of two to three months because some conditions can affect sperm levels.

    The semen analysis also can be used to count sperm after a man has a vasectomy. If there are still a lot of sperm present in the semen, the man and his partner will have to take precautions so that his partner will not become pregnant. He will have to return for one or more sperm counts until the sperm are cleared from his sample(s).

  • When is it ordered?
    A semen analysis is recommended following a vasectomy and when a physician thinks that the patient might have a fertility problem. At least 10%-20% of married couples experience problems conceiving. Male factors are implicated about 40% of the time. Male infertility has many causes and some of these, such as varicocele (enlargement of the veins draining the testes), can be treated successfully. If male factors are involved, analysis of the semen is necessary to determine the feasibility of using assisted reproductive technology to facilitate pregnancy.
  • What does the test result mean?
    The typical volume of semen collected is around one-half to one teaspoonful (2-6 milliliters) of fluid. Less semen would indicate fewer sperm, which would affect fertility. More semen indicates too much fluid, which would dilute the sperm, also impeding fertility.

    Sperm concentration (also called sperm density) is measured in millions of sperm per milliliter of semen. Normal is greater than or equal to 20 million per milliliter (and more than 80 million sperm in one ejaculation). The fewer sperm a sample has, the less chance a man has of getting a woman pregnant. A man who has just had a vasectomy would want to have no sperm in his sample.

    Motility is the percentage of moving sperm in a sample. The more slowly moving or immobile sperm in a sample, the less likely it is that a man could get a woman pregnant. The progression of the sperm is rated on a basis from zero (no motion) to 3 or higher for sperm that move in a straight line with good speed. If less than half of the sperm are motile, a stain is used to identify the percentage of dead sperm. This is called a sperm viability test.

    Morphology analysis is the study of the size, shape, and appearance of the sperm cells. The analysis evaluates the structure of 200 sperm, and any defects are noted. The more abnormal sperm that are present, the lower the likelihood of fertility.

  • Is there anything else I should know?
    Several factors can affect the sperm count and other semen analysis values. A man may have a lower sperm count if he has physical damage to the testicles, has gone through radiation treatment of his testicles, or has had exposure to certain drugs (such as azathioprine or cimetidine). A man with a higher level of estrogens may have lower sperm counts.

    Some of the common causes of male infertility are extremely high fever, failure of the testicles, obstruction of the tubes that carry semen to the penis, and a less than normal amount of sperm in the sample (oligospermia).

  • What are the biggest signs of fertility in a semen analysis, out of the all of the many things that are checked?
    Sperm count (number of sperm), motility (percentage of living sperm), and morphology (normal shape of the sperm) are most closely linked with good fertility rates.
  • I had good motility on my first sperm sample, but later it was very low. What could cause that?
    If you had a good motility on the first reading, you may have a low sperm motility later because of a genital infection or because of an inflamed prostate gland.
  • I would like to have my sperm tested, because my wife is having trouble getting pregnant. For various reasons, I don’t want to have my sperm collected in the doctor’s office. For religious reasons, I don’t want to wear a condom during th
    Masturbation in the privacy of your home would be the best solution. A small pinprick in the condom may be an acceptable compromise for you if you must collect the sample during intercourse.
  • Shouldn’t they check my wife’s fertility first?
    When a couple cannot become pregnant, it is much easier, less invasive, and less expensive for the man to be tested first. A man requires only semen analysis, and the samples can be collected and ruled out very quickly. If the man’s semen is normal, then it makes sense to move ahead with the more invasive and expensive tests for female infertility.
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View Sources
S1
Clinical Guide to Laboratory Tests (third edition), Norbert W. Tietz, editor. Philadelphia: W.B. Saunders & Co., 1995; pp. 554-556.

S2
Laboratory Tests & Diagnostic Procedures with Nursing Diagnoses (4th edition), Corbett, JV. Stamford, Conn.: Appleton & Lang, 1996. pp. 727-728.

S3
Robert Harr, M.S. MT(ASCP). Associate Professor and Chair, Department of Public and Allied Health; Program Director, Medical Technology, Bowling Green State University.

S4
Larry J. Kricka, PhD. American Association for Clinical Chemistry, President. University of Pennsylvania Medical Center, Philadelphia, PA.

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