A semen analysis measures the amount of semen a man produces and determines the number and quality of sperm in the semen sample.
A semen analysis is usually one of the first tests done to help determine whether a man has a problem fathering a child (infertility). A problem with the semen or sperm affects more than one-third of the couples who are unable to have children (infertile).
Tests that may be done during a semen analysis include:
- Volume. This is a measure of how much semen is present in one ejaculation.
- Liquefaction time. Semen is a thick gel at the time of ejaculation and normally becomes liquid within 20 minutes after ejaculation. Liquefaction time is a measure of the time it takes for the semen to liquefy.
- Sperm count. This is a count of the number of sperm present per milliliter (mL) of semen in one ejaculation.
- Sperm morphology. This is a measure of the percentage of sperm that have a normal shape.
- Sperm motility. This is a measure of the percentage of sperm that can move forward normally. The number of sperm that show normal forward movement in a certain amount of semen can also be measured (motile density).
- pH. This is a measure of the acidity (low pH) or alkalinity (high pH) of the semen.
- White blood cell count. White blood cells are not normally present in semen.
- Fructose level. This is a measure of the amount of a sugar called fructose in the semen. The fructose provides energy for the sperm.
Why It Is Done
A semen analysis is done to determine whether:
- A man has a reproductive problem that is causing infertility.
- A vasectomy has been successful.
- The reversal of a vasectomy has been successful.
How To Prepare
You may be asked to avoid any sexual activity that results in ejaculation for 2 to 5 days before a semen analysis. This helps ensure that your sperm count will be at its highest, and it improves the reliability of the test. If possible, do not avoid sexual activity for more than 1 to 2 weeks before this test, because a long period of sexual inactivity can result in less active sperm.
You may be asked to avoid drinking alcohol for a few days before the test.
Be sure to tell your doctor about any medicines or herbal supplements you are taking.
How It Is Done
You will need to produce a semen sample, usually by ejaculating into a clean sample cup. You can do this in a private room or in a bathroom at your doctor's office or clinic. If you live close to your doctor's office or clinic, you may be able to collect the semen sample at home and then transport it to the office or clinic for testing.
- The most common way to collect semen is by masturbation, directing the semen into a clean sample cup. Do not use a lubricant.
- You can collect a semen sample during sex by withdrawing your penis from your partner just before ejaculating (coitus interruptus). You then ejaculate into a clean sample cup. This method can be used after a vasectomy to test for the presence of sperm, but other methods will likely be recommended if you are testing for infertility.
- You can also collect a semen sample during sex by using a condom. If you use a regular condom, you will need to wash it thoroughly before using it to remove any powder or lubricant on it that might kill sperm. You may also be given a special condom that does not contain any substance that kills sperm (spermicide). After you have ejaculated, carefully remove the condom from your penis. Tie a knot in the open end of the condom and place it in a container that can be sealed in case the condom leaks or breaks.
If any of these methods are against your beliefs, talk with your doctor about different methods of collection.
If you collect the semen sample at home, the sample must be received at the laboratory or clinic within 1 hour. Keep the sample out of direct sunlight and do not allow it to get cold or hot. If it is a cold day, carry the semen sample container against your body to keep it as close to body temperature as possible. Do not refrigerate the semen sample.
Since semen samples may vary from day to day, 2 or 3 different samples may be evaluated within a 3-month period for accurate testing.
A semen analysis to test the effectiveness of a vasectomy is usually done 6 weeks after the vasectomy.
How It Feels
Producing a semen sample does not cause any discomfort. But you may feel embarrassed about the method used to collect it.
There are no risks associated with collecting a semen sample.
A semen analysis measures the amount of semen a man produces and determines the number and quality of sperm in the semen sample. Results of a semen analysis are usually available within a day. Normal values may vary from lab to lab.
2–5 milliliters (mL) (0.002–0.005 L in SI units) per ejaculation
An abnormally low or high semen volume is present, which may sometimes cause fertility problems.
20–30 minutes after collection
An abnormally long liquefaction time is present, which may indicate an infection.
20 million spermatozoa per milliliter (mL) or more
0 sperm per milliliter if the man has had a vasectomy
A very low sperm count is present, which may mean infertility. But a low sperm count does not always mean that a man cannot father a child. Men with sperm counts below 1 million have fathered children.
Sperm shape (morphology)
More than 30% of the sperm have normal shape.
Kruger criteria: More than 14% of the sperm have a normal shape.
Sperm can be abnormal in several ways, such as having two heads or two tails, a short tail, a tiny head (pinhead), or a round (rather than oval) head. Abnormal sperm may be unable to move normally or to penetrate an egg. Some abnormal sperm are usually found in every normal semen sample. But a high percentage of abnormal sperm may make it more difficult for a man to father a child.
Sperm movement (motility)
More than 50% of the sperm show normal forward movement after 1 hour.
Sperm must be able to move forward (or "swim") through cervical mucus to reach an egg. A high percentage of sperm that cannot swim properly may impair a man's ability to father a child.
Semen pH of 7.1–8.0
An abnormally high or low semen pH can kill sperm or affect their ability to move or to penetrate an egg.
White blood cells
No white blood cells or bacteria are detected.
Bacteria or a large number of white blood cells are present, which may indicate an infection.
Certain conditions may be linked with a low or absent sperm count. These conditions include orchitis, varicocele, Klinefelter syndrome, radiation treatment to the testicles, or diseases that can cause shrinking (atrophy) of the testicles (such as mumps).
If a low sperm count or a high percentage of sperm abnormalities are found, further testing may be done. Other tests may include measuring hormones, such as testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), or prolactin. A small sample (biopsy) of the testicles may be needed for further evaluation if the sperm count or motility is extremely low.
What Affects the Test
Reasons you may not be able to have the test or why the results may not be helpful include:
- Medicines, such as cimetidine (Tagamet), male and female hormones (testosterone, estrogen), sulfasalazine, nitrofurantoin, and some chemotherapy medicines.
- Caffeine, alcohol, cocaine, marijuana, and smoking tobacco.
- Herbal medicines, such as St. John's wort and high doses of echinacea.
- A semen sample that gets cold. The sperm motility value will be inaccurately low if the semen sample gets cold.
- Exposure to radiation, some chemicals (such as certain pesticides or spermicides), and prolonged heat exposure.
- An incomplete semen sample. This is more common if a sample is collected by methods other than masturbation.
- Not ejaculating for several days. This may affect the semen volume.
What To Think About
- A semen sample collected at home must be received at the laboratory or clinic within 1 hour. Keep the sample out of direct sunlight and do not allow it to get cold or hot. If it is a cold day, carry the semen sample container against your body to keep it as close to body temperature as possible. Do not refrigerate the semen sample.
- Consistently detecting sperm in the semen of a man who has had a vasectomy means that his surgery was not successful, and another form of birth control should be used to prevent pregnancy. A low number of sperm may be present in a semen sample taken right after a vasectomy. But sperm should not be present in subsequent samples.
- A man whose mother took the medicine diethylstilbestrol (DES) during her pregnancy with him has a greater-than-normal risk of being unable to father a child (infertile).
- More tests may include measuring hormone levels, such as testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), or prolactin. For more information, see the topics Testosterone, Luteinizing Hormone, Follicle-Stimulating Hormone, and Prolactin.
- Other fertility testing, including sperm penetration, the presence of antisperm antibodies, or analysis after sexual intercourse (postcoital), may be recommended for infertility problems. For more information, see the topic Infertility Testing.
Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
Other Works Consulted
Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.
Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
Fritz MA, Speroff L (2011). Male infertility. In Clinical Gynecologic Endocrinology and Infertility, 8th ed., pp. 1249–1292. Philadelphia: Lippincott Williams and Wilkins.
Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby.
|Primary Medical Reviewer||Sarah Marshall, MD - Family Medicine|
|Specialist Medical Reviewer||Femi Olatunbosun, MB, FRCSC - Obstetrics and Gynecology|
|Last Revised||February 9, 2012|