Semen Analysis

Performing a complete analysis of the semen is a major part of the male fertility assessment. This test checks for both the quality and quantity of sperm. The semen sample is obtained by the male partner performing masturbation. In some cases, the sample may be obtained at home. In other situations, the semen sample must be obtained at the clinic or laboratory.

Many fertility specialists recommend that the male partner refrain from sexual activity for at least three days prior to this test. That's because this is a reasonable amount of time to accurately evaluate an average sperm sample. However, because sperm counts and quality can vary, this test will likely be performed on several different occasions over the next few months.

Once the semen sample is obtained, it is analyzed in the laboratory. The semen sample is typically evaluated under a microscope and/or by computerized evaluation. The key features studied are:

• Volume—the amount of semen per ejaculation

• Thickness (viscosity)—the consistency of the semen

• Quantity (concentration)—the number of sperm present in the semen

• Shape (morphology)—the percentage of normally shaped sperm

• Movement (motility)—the ability of the sperm to travel and move forward properly

Volume

The total volume of semen per ejaculation is normally about one-half to one teaspoon. In scientific terms, that translates to about two milliliters. However, normal volume is considered one to six and a half milliliters per ejaculation. Higher or lower volumes may be associated with fertility problems.

However, the actual volume of semen does not necessarily correlate with the quantity of the sperm. Some men have low ejaculate volumes but high sperm count. Others may have high ejaculate volumes and low sperm count.

A low volume may mean that the semen does not contain all of the normal components of normal semen or may indicate a low testosterone level. A very high volume of semen may indicate an infection.

Some men do not have any semen at all. This may be due to retrograde ejaculation, where the sperm go backward into the bladder. It may also be related to a medical condition such as diabetes, prior surgery, or certain medications.

Thickness

The semen analysis takes a look at the thickness of the semen and the time it takes to liquefy. At the time of ejaculation, normal semen is a thick gel. Semen typically becomes a liquid within 20 minutes after ejaculation. This test measures the time for the semen sample to liquefy. If it takes longer than 60 minutes, this is abnormal and may be a sign of infection or other problems.

If the semen appears clumpy, this may indicate that a problem exists in the prostate gland. That's because the prostate gland is supposed to provide enzymes that cause the ejaculate to liquefy. On the other hand, if the semen appears runny, a problem may exist in the seminal vesicles. The seminal vesicles contribute proteins that cause the ejaculate to coagulate.

Quantity

One of the main components of a semen analysis is to count the number of sperm produced in the sample. The sperm count is estimated by careful analysis under a laboratory microscope. Normally, a fertile male ejaculates about 60 million or more sperm per milliliter. Although laboratory values may vary, most labs consider 20 to 150 million sperm per milliliter to be within the normal range.

There can be variations among sperm count even for the same person. Outside factors, such as a cold or flu, extreme stress, or another medical condition, may adversely affect a man's sperm count.

Upon occasion, some men may register a zero for sperm count. If this occurs, further testing is needed. Typically, the next test is checking the semen for the presence of a sugar called fructose. During normal sperm production, fructose is added to the semen by the epididymis. Therefore, if fructose is not present, there may be a blockage along the male's reproductive tract that is preventing the sperm from getting into the ejaculate. If fructose is present in the semen, this suggests that there may be a problem in the testicles' ability to manufacture sperm.

Even if the sperm count is normal, the sperm is not necessarily of good quality. For that, the semen analysis evaluates the shape and movement of the sperm.

Shape

A sperm that is shaped normally is more likely to fertilize the egg than one with a structural abnormality. It is considered a good sign of fertility to have at least 60 percent normally shaped sperm in a semen sample.

It's perfectly normal to have some abnormally shaped sperm in every semen sample. Sperm can be abnormally shaped in several ways, such as having two heads, two tails, a short tail, a tiny head (pinhead), or a round (instead of oval) shaped head. Abnormal sperm typically cannot move normally or penetrate an egg.

Movement

Another important component of the semen analysis is the study of how sperm move. The speed and direction of the sperm affect its ability to reach and then penetrate an egg. Under normal circumstances, sperm that have good motility can move through a woman's reproductive tract at the rate of two inches per hour. It is considered normal for at least 50 percent of the ejaculated sperm to demonstrate normal forward movement.

If a high percentage of sperm cannot "swim," or move forward, through the cervical mucus and female reproductive tract to reach an egg, then the man's fertility is likely impaired.

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