Semen Analysis

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Also known as: Sperm analysis; Sperm count; Seminal fluid analysis

Formal name: Semen Analysis

Related tests: Antisperm antibody test; FSH; LH; Testosterone; Prolactin

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.

The Test Sample

What is being tested?

A semen analysis measures the quantity and quality of the fluid released from the penis during ejaculation. It evaluates both the liquid portion, called semen, and the microscopic, moving cells, called sperm.

Semen is a viscous, whitish liquid that contains sperm and the products from several glands. It is normally fairly thick after ejaculation and then thins, liquefying within 10 to 30 minutes. Sperm are reproductive cells in semen that have a head and a tail. Each sperm contains 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. In each semen sample, there are millions of sperm and varying amounts of fructose, 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
Consistency (thickness) of the semen
Sperm concentration (density)
Total number of sperm
Sperm motility (percent able to move as well as how vigorously and straight the sperm move)
Number of normal and not normal (defective) sperm
Coagulation and liquefaction
Fructose (a sugar in semen)
pH (acidity)
Number of immature sperm
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 such as in vitro fertilization is contemplated, 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 laboratories 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 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 or heated.

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?

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.

The Test

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 tests 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 the sperm count and semen consistency will vary from day to day and some conditions can temporarily affect sperm levels.

The semen analysis also can be used to count sperm after a man has a vasectomy. If there are still sperm present in the semen, whether alive and still motile or apparently dead, the man and his partner will have to take precautions so that the woman does not become pregnant. He will have to return for one or more sperm counts until sperm are no longer present in his sample(s).

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When is it ordered?

A semen analysis is performed when a physician thinks that a person or couple might have a fertility problem. At least 10%-20% of married couples experience problems conceiving. Male factors are implicated about 30% of the time and combined male and female factors about 20% of the time. Male infertility has many causes and some of these, such as enlargement of the veins draining the testes (varicocele), can be treated successfully. If male factors are involved, analysis of the semen is necessary to determine what is inhibiting fertility and, when indicated, to evaluate the feasibility of using assisted reproductive technology to facilitate pregnancy. When a semen analysis is abnormal, then the test is repeated at intervals determined by the doctor.

A semen analysis is typically ordered following a vasectomy and repeated as necessary until sperm are no longer present in the semen sample.

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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 total sperm, which may affect fertility. More semen indicates too much fluid, which may dilute the concentration of sperm. The semen should initially be thick and then liquefy within 10 to 30 minutes. If this does not occur, then it may impede sperm movement.

Sperm concentration (also called sperm density) is measured in millions of sperm per milliliter (mL) of semen. Normal is 20 million or more sperm per mL, with a total of 80 million or more sperm in one ejaculation. Fewer sperm and/or a lower sperm concentration may impair fertility. Following a vasectomy, the goal is to have no sperm detected in the semen sample.

Motility is the percentage of moving sperm in a sample and an evaluation of their rate and direction of travel. At least 50% should be motile one hour after ejaculation, and they should be 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 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. Abnormal forms may include defective heads, middles, 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, fructose at 150-600 mg/dL, and there should be less than 2000 white blood cells per mL.

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Is there anything else I should know?

When a doctor is evaluating a man's fertility, each aspect of the semen analysis is considered, as well as the findings as a whole. Each part of the semen analysis either contributes to fertility or lessens it, but the results do not necessarily predict the eventual outcome. Couples with poor results may still conceive, with or without assistance, and those with apparently good results may experience difficulties.

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).

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Common Questions

1. What are the biggest signs of fertility in a semen analysis, out of 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.

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2. 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.

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3. I would like to have my sperm tested. 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 the sex act. What can I do?

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.

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4. 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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Article Sources

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.

Sources Used in Current Review

Dugdale III, D. (Updated 2008 May 21). Semen Analysis. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003627.htm. Accessed February 2010.

Rubenstein, J. and Brannigan, R (Updated 2008 March 26). Infertility, Male. eMedicine [On-line information]. Available online at http://emedicine.medscape.com/article/436829-overview through http://emedicine.medscape.com. Accessed February 2010.

Bayrak-Toydemir, P. et. al. (Updated 2009 August) Infertility. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/Infertility.html# through http://www.arupconsult.com. Accessed February 2010.

Rebar, R. (Revised 2008 November) Infertility, Sperm Disorders. Merck Manual for Healthcare Professionals [On-line information]. Available online at http://www.merck.com/mmpe/sec18/ch256/ch256b.html?qt=semen analysis&alt=sh through http://www.merck.com. Accessed February 2010.

Sources Used in Previous Reviews

Clinical Guide to Laboratory Tests (third edition), Norbert W. Tietz, editor. Philadelphia: W.B. Saunders & Co., 1995; Pp. 554-556.

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

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

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