Semen analysis

Semen is the cloudy, whitish substance released from the penis during ejaculation. Sperm are the cells in semen, with a head and a tail that allow them to move towards the egg. A sperm cell contains one copy of each chromosome (all of the man’s genes) and fuses with the woman’s egg, resulting in fertilisation.

A typical semen analysis measures:

• The volume of semen,
• The consistency or thickness of the semen,
• The sperm concentration,
• The total number of sperm,
• Sperm motility (the percentage able to move, as well as how vigorously and easily the sperm move),
• The number of normal and abnormal (defective) sperm,
• Coagulation and liquefaction,
• Fructose (a sugar found in semen),
• pH (acidity),
• the number of immature sperm
• the number of white blood cells (cells that indicate infection).

Further tests may be done if the semen is abnormal, such as a test for sperm antibodies. If assisted reproduction (e.g. in vitro fertilisation) is planned, sperm function tests may also be carried out. Sometimes a test called cryosurvival is done to see whether the sperm will survive long-term storage, if a couple wishes to store sperm for future pregnancies.

How is the sample collected for testing?
Most laboratories require samples to be collected on site, as semen must be examined within an hour of ejaculation. Semen is collected in a private room, usually a bathroom. The man masturbates and collects the semen in a glass container. Some men, for religious or other reasons, may wish to collect semen during intercourse using a condom. In this case the doctor should provide the condom or sheath, because lubricated condoms can alter the test results. Sperm are very sensitive to temperature. If the sample is collected at home, it must always be kept at room temperature (70°F/21°C). Never refrigerate the sample and never try to warm it to body temperature.

How is it used?
When is it requested?
What does the test result mean?
Is there anything else I should know?

How is it used?
Semen analysis is used to determine whether a man may be infertile, i.e. unable to make a woman pregnant. The analysis is made up of many parts and examines many aspects of the semen and sperm. Fertility testing should be carried out on at least two samples taken at least seven days apart over a period of two to three months, as some conditions can change sperm levels.

Semen analysis can also be used to count sperm after a vasectomy. If many sperm are still present in the semen, the man and his partner will need to take precautions to avoid pregnancy. He will need to return for one or more sperm counts until there are none left in his sample.

When is it requested?
Semen analysis is recommended after a vasectomy and when the doctor thinks the patient may have a fertility problem. At least 10-20% of married couples have problems conceiving, and in about 40% of cases male factors are involved. Male infertility has many causes, and some of them, such as varicocele (enlarged veins draining the testicles), can be treated successfully. If male factors are involved, semen analysis is needed to determine whether assisted reproduction techniques can be used to help achieve a pregnancy.

What does the test result mean?
The typical volume of semen collected is about half to one teaspoon (2-6 millilitres) of fluid. Less semen would mean fewer sperm, which would affect fertility. More semen means too much fluid, which would dilute the sperm, also limiting fertility.

Sperm concentration (also called density) is measured in millions of sperm per millilitre of semen. Normal is 20 million or more per millilitre (and more than 80 million sperm per ejaculation). The fewer sperm a sample has, the lower the chance that a man can make a woman pregnant. A man who has just had a vasectomy should have no sperm in his sample.

Motility is the percentage of sperm moving in a sample. The more sperm that move slowly or not at all, the lower the chance that a man can make a woman pregnant. Sperm movement is scored from zero (no movement) to 3 or more for sperm moving in a straight line at good speed. If fewer than half the sperm are motile, a dye is used to identify the percentage of dead sperm. This is called a sperm vitality test.

Morphology analysis is the study of the size, shape and appearance of sperm cells. The structure of 200 sperm is assessed and any defects are noted. The more abnormal sperm there are, the lower the chance of fertility.

Is there anything else I should know?
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 had radiation treatment to the testicles or has taken certain medicines (such as azathioprine or cimetidine). A man with high oestrogen levels may have a lower sperm count. Some common causes of male infertility are very high fever, testicular failure, blockage of the ducts that carry semen to the penis and a low sperm concentration (oligospermia).

1. Of all the things checked in a semen analysis, what are the main signs of fertility?
2. I had good motility in my first sperm sample, but later it was very low. What could be the cause?
3. I would like my sperm tested because my wife cannot get pregnant. For various reasons I do not want to collect the sample at the doctor’s surgery, and for religious reasons I do not want to use a condom during intercourse. What can I do?
4. Shouldn’t my wife’s fertility be checked first?

1. Of all the things checked in a semen analysis, what are the main signs of fertility?The sperm count (number of sperm), motility (percentage of live, moving sperm) and morphology (normal shape of the sperm) are most closely linked to good fertility rates.

2. I had good motility in my first sperm sample, but later it was very low. What could be the cause?
If motility was good at the first check, the later lower motility may be caused by a genital infection or an inflamed prostate.

3. I would like my sperm tested because my wife cannot get pregnant. For various reasons I do not want to collect the sample at the doctor’s surgery, and for religious reasons I do not want to use a condom during intercourse. What can I do?
Masturbation in the privacy of your home would be the best solution. A tiny hole in the condom could be an acceptable compromise if you want to collect the sample during intercourse.

4. Shouldn’t my wife’s fertility be checked first?
When a couple cannot achieve a pregnancy, it is much easier, less invasive and less expensive to test the man first. The man only needs a semen analysis, and samples can be collected and examined very quickly. If the man’s semen is normal, it then makes sense to proceed with the more invasive and more expensive tests for female infertility.