Semen Analysis

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.