Semen Analysis [en Español]
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This test is usually one of the first tests done to help find out if a man has a problem fathering a child ( infertility ). A problem with the semen or sperm affects more than one-third of 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. It normally becomes liquid within 20 minutes after ejaculation. Liquefaction time is the time it takes for the semen to turn to liquid.
- Sperm count. This counts 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. This is called 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 find out if:
- A man has a reproductive problem that is causing him to be infertile.
- 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 this test. This helps to make sure that your sperm count will be at its highest. It also makes the test more reliable. If possible, do not avoid sexual activity for more than 1 to 2 weeks before this test. A long time without sexual activity 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 take.
How It Is Done
You will need to produce a semen sample. This is usually done 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. Then you can take it to the office or clinic for testing.
- The most common way to collect semen is by masturbation. You direct 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 you ejaculate. 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 ways 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 well before you use it. This helps to remove any powder or lubricant on the condom that might kill sperm. You may also be given a special condom that does not have any substance on it that kills sperm (spermicide). After you ejaculate, carefully remove the condom from your penis. Tie a knot in the open end of the condom. Then 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 ways to get a sample.
If you collect the semen sample at home, the sample must be given to the lab or clinic within 1 hour. Keep the sample out of direct sunlight. And do not let it get cold or hot. If it is a cold day, carry the semen sample container against your body. This helps 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, two or three different samples may be checked within a 3-month period. This helps to get accurate testing.
A semen analysis to test how well a vasectomy has worked is usually done 6 weeks after the vasectomy.
How It Feels
Getting 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. It also shows 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. This may sometimes cause fertility problems.
20–30 minutes after collection
An abnormally long liquefaction time is present. This may be a sign of 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. This may mean infertility . But a low sperm count does not always mean that a man can't 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. They may have two heads or two tails, a short tail, a tiny head (pinhead), or a round (rather than oval) head. Abnormal sperm may not be able to move normally or to penetrate an egg. Some sperm that aren't normal are usually found in every normal semen sample. But a high percentage of abnormal sperm may make it harder 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 can't swim well may make it harder for a man to father a child.
Semen pH of 7.1–8.0
An abnormally high or low semen pH can kill sperm or affect how well they can move or can penetrate an egg.
White blood cells
No white blood cells or bacteria are found.
Bacteria or a large number of white blood cells are present. This may be a sign of 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 , and diseases that can cause shrinking (atrophy) of the testicles (such as mumps ).
If a low sperm count or a high percentage of abnormal sperm is found, more 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 need to be checked if the sperm count or motility is extremely low.
What Affects the Test
You may not be able to have the test, or the results may not be helpful, if:
- You take medicines such as cimetidine (Tagamet), male or female hormones (testosterone, estrogen ), sulfasalazine, nitrofurantoin, or some chemotherapy medicines.
- You use caffeine, alcohol, cocaine, marijuana, or tobacco.
- You use herbal medicines, such as St. John's wort or high doses of echinacea.
- Your semen sample gets cold. The sperm motility value will be low and not accurate if the semen sample gets cold.
- You are exposed to radiation, some chemicals (such as certain pesticides or spermicides), or prolonged heat.
- Your semen sample is incomplete. This is more common if a sample is collected by ways other than masturbation.
- You have not ejaculated for several days. This may affect the semen volume.
What To Think About
- A home test kit to check the sperm count has been approved by the U.S. Food and Drug Administration (FDA). This test can help a man find out if he has fertility problems.
- A semen sample collected at home must be given to 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. This helps to keep it as close to body temperature as possible. Do not refrigerate the semen sample.
- If sperm is consistently found in the semen of a man who has had a vasectomy, it means that his surgery was not successful. If this happens, 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 samples taken later than that.
- A man whose mother took the medicine diethylstilbestrol (DES) while pregnant with him has an increased risk of being unable to father a child (infertile).
- More tests may include measuring hormone levels, such as:
- Other fertility testing may be recommended for fertility problems. This includes sperm penetration and the presence of antisperm antibodies. To learn more, 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 (2013). Laboratory Tests and Diagnostic Procedures, 6th 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
Current as ofMay 22, 2015
Current as of: May 22, 2015
Author: Healthwise Staff
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