Patient Test Information

Semen Analysis

Also known as:

Sperm Analysis; Sperm Count; Seminal Fluid Analysis

Formal name:

Semen Analysis

Related tests:

Antisperm Antibody Test; FSH; LH; Testosterone; Prolactin; Urinalysis

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Why Get Tested?

As part of infertility testing 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 about three months after you have had a vasectomy

Sample Required?

A semen sample collected in a sterile, wide-mouth container provided by the lab; often collected on-site, but sometimes it may be collected at home using a special condom obtained from a healthcare practitioner. For infertility testing, the sample must be analyzed within one hour of collection. Two separate collections on two separate days may be required.

Test Preparation Needed?

For infertility testing, refrain from having sex or masturbation for 2-5 days before sample collection; carefully follow instructions provided.

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 consists of a series of tests that evaluate the quality and quantity of the sperm as well as the semen, the fluid that contains them. The test may be used, in conjunction with other infertility tests, to help determine the cause of a couple's inability to get pregnant (conceive) and to help guide decisions about infertility treatment.

The semen analysis also can be used to determine whether sperm are present in semen after a man has had a vasectomy, a surgical procedure that prevents sperm from being released within the ejaculate. This surgery is considered a permanent method of birth control (99.9%) when performed successfully.

When is it ordered?

A semen analysis is performed when a healthcare practitioner thinks that a man or couple might have a fertility problem. Infertility is typically diagnosed when a couple has tried to get pregnant for 12 months without success.

A semen analysis to determine fertility should be performed on a minimum of two samples collected within 2 to 3 week intervals. Sperm count and semen consistency can vary from day to day, and some conditions can temporarily affect sperm motility and numbers.

When a semen analysis shows abnormal findings, the test is repeated at intervals as determined by the healthcare practitioner.

A shorter version of a semen analysis, a sperm check, is typically ordered about 3 months following a vasectomy to confirm success of the procedure and may be repeated as necessary until sperm are no longer present in the semen sample.

What does the test result mean?

Post-vasectomy sperm check: Couples may discontinue using other methods of contraception when there are no sperm or rare non-motile sperm seen in the semen. If sperm are present in the semen, the man and his partner will have to take precautions to avoid pregnancy. Testing may be repeated until sperm are no longer present in his sample(s).

infertility testing: In an evaluation of a man's fertility, each aspect of the semen analysis is considered, as well as the findings as a whole. Semen from a man can vary widely from sample to sample. Abnormal results on one sample may not indicate a cause of infertility, and multiple samples may need to be tested before a diagnosis is made.

  • Volume–the typical volume of semen collected is between 1.5 and 5 milliliters (about a teaspoon) of fluid per ejaculation. Decreased volume of semen would indicate fewer sperm, which diminishes opportunities for successful fertilization and subsequent pregnancy. Excessive seminal fluid may dilute the concentration of sperm.
  • Viscosity–the semen should initially be thick and then liquefy within 15 to 20 minutes. If this does not occur, then it may impede sperm movement.
  • Sperm concentration (also called sperm count or sperm density)–this is measured in millions of sperm per milliliter of semen. Normal is at least 20 million or more sperm per milliliter, with a total ejaculate volume of 80 million or more sperm. Fewer sperm and/or a lower sperm concentration may impair fertility.
  • Motility–the percentage of moving sperm in a sample; it is graded based on speed and direction travelled. At least 50% should be motile one hour after ejaculation, moving forward in a straight line with good speed. The progression of the sperm is rated on a basis from zero (no motion) to 4, with 3-4 representing good motility. 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–the study of the size, shape, and appearance of the sperm cells; the analysis evaluates the structure of the sperm. More than 50% of those cells examined should be normal in size, shape, and length. The more abnormal sperm that are present, the greater the likelihood of infertility. Abnormal forms may include defective heads, midsections, tails, and immature forms. To see an image of a normal sperm, see the MedlinePlus Medical Encyclopedia page on sperm
  • Semen pH–should be between 7.2 and 7.8. A pH of 8.0 or higher may indicate an infection, while a pH less than 7.0 suggests contamination with urine or an obstruction in the ejaculatory ducts.
  • Fructose–concentration should be greater than 150 milligrams per deciliter of semen.
  • White blood cells–there should be fewer than 1 million white blood cells per milliliter.
  • Agglutination of sperm–this occurs when sperm stick together in a specific and consistent manner (head to head, tail to tail, etc.), suggesting the presence of antisperm antibodies. Clumping of sperm in a nonspecific manner may be due to bacterial infection or tissue contamination.

Is there anything else I should know?

While abnormal results decrease the chances of fertilization, some couples with poor results on infertility tests may still conceive, with or without assistance, and those with apparently good results may experience difficulties.

Several factors can affect the sperm count or other semen analysis values, including use of alcohol, tobacco, caffeine, many recreational and prescription drugs (e.g., cimetidine), and some herbal medicines such as St. John's Wort.

What is being tested?

A complete semen analysis measures the quantity and quality of the fluid released during ejaculation. It evaluates both the liquid portion, called semen or seminal fluid, and the microscopic, moving cells called sperm. It is often used in the evaluation of male infertility. A shorter version of this test checks solely for the presence of sperm in semen a few months after a man has had a vasectomy to determine whether the surgery was successful.

Semen is a viscous, whitish liquid that contains sperm and the products from several glands. It is fairly thick at ejaculation but thins out, or liquefies, within 10 to 30 minutes. Sperm are reproductive cells in semen that have a head, midsection, and a tail and contain one copy of each chromosome (all of the male's genes). Sperm are motile, normally moving forward through the semen. Inside a woman's body, this property enables them to travel to and fuse with the female's egg, resulting in fertilization. Each semen sample is between 1.5 and 5.5 milliliters (about one teaspoon) of fluid, containing at least 20 million sperm per milliliter, and varying amounts of fructose (a sugar), buffers, coagulating substances, lubricants, and enzymes that are intended to support the sperm and the fertilization process.

A typical semen analysis measures:

  • Volume of semen
  • Viscosity–consistency or thickness of the semen
  • Sperm count–total number of sperm
  • Sperm concentration (density)–number of sperm per volume of semen
  • Sperm motility–percent able to move as well as how vigorously and straight the sperm move
  • Number or percent of normal and abnormal (defective) sperm in terms of size and shape (morphology)
  • Coagulation and liquefaction–how quickly the semen turns from thick consistency to liquid
  • Fructose–a sugar in semen that gives energy to sperm
  • pH–measures acidity
  • Number of immature sperm
  • Number of white blood cells (cells that indicate infection)

Additional tests may be performed if the sperm count is low, if the sperm show decreased motility or abnormal morphology, or if the seminal fluid is found to be abnormal. These additional tests may help identify abnormalities such as the presence of sperm antibodies, abnormal hormone levels (testosterone, FSH, LH, prolactin), excessive number of white blood cells, and genetic tests for conditions that may affect fertility, such as Klinefelter syndrome, cystic fibrosis, or other chromosomal abnormality.

In some instances, imaging tests such as ultrasound, CAT scan, or MRI may be required. A biopsy of the testicle may also be needed. 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?

Post-vasectomy sperm check: a semen sample is collected in a clean, wide-mouth container provided by the lab.

Infertility evaluation: Most laboratories require samples to be collected on-site as the semen needs to be examined within 60 minutes after ejaculation in order to maintain the quality of the specimen.

Semen is collected in a private area by self-stimulation. 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 healthcare practitioner 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 body temperature (98.6oF/37oC) by keeping it next to the body during transportation. It should not be left at room temperature for an extended period of time and should not be refrigerated.

Sperm motility decreases after ejaculation; thus, timing and temperature are critical to obtaining accurate results. If the sample is poor, repeat testing might be needed.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

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

For infertility testing: To give sperm a chance to replenish, abstain from ejaculating for 2 to 5 days before the sample is collected. Longer periods of abstinence may result in a greater volume of semen but decreased sperm motility. You may also be asked to avoid alcohol consumption for a few days before the test as well. Follow any instructions that are provided.

Post-vasectomy: Men may be advised to have regular ejaculations every 3-4 days to clear sperm from the reproductive tract more quickly.

  1. What proportion of infertility cases are caused by male fertility problems?

    About one-third of cases are due to men's problems with fertility, another third are due to women's problems, and the remaining cases are due to a combination of men's and women's infertility issues or have no clear identifiable reasons for infertility.

  2. Is a home sperm count test available?

    Yes, there is a home test available that measures sperm count and gives a result within a few minutes. However, it is important to understand that a sperm count is only one part of a semen analysis for determination of male fertility and is only one aspect of a complex process. For more about home tests, including the benefits and cautions, see the article With Home Testing, Consumers Take Charge of Their Health.

  3. What causes male infertility?

    Some of the common causes of male Infertility include damage to the testicles from infections (such as mumps), chemotherapy/radiation, trauma or surgery, obstruction of the tubes that carry semen to the penis caused by scarring from an infection or having cystic fibrosis, a varicocele (an enlarged collection of blood vessels in the scrotum that raises the temperature of the testicles, which can lead to low sperm production), having the genetic condition Klinefelter syndrome, and anything that lowers levels of the hormones LH and FSH, such as a pituitary tumor. Chronic illness, poor overall health, obesity, certain medications, and drug abuse may also decrease sperm production and fertility.

  4. What is the treatment for male infertility?

    Treatment will depend on the cause. It could include surgery to repair a varicocele or a blockage, hormone injections, or use of assisted reproductive technologies. To learn more, read the article on Infertility.