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The semen liquefaction
Semen analysis should begin with a simple inspection soon after liquefaction. This is done preferably at 30 minutes after ejaculation but no longer than one hour to prevent dehydration or changes in temperature from affecting semen quality. Normal liquefied semen samples may contain jelly-like granules (gelatinous bodies) which do not liquefy. These do not appear to have any clinical significance. Poor liquefaction means the sperm may not be released to fertilize the egg.
The following are the normal settings
- Immediately after ejaculation into the collection vessel, semen is typically a semisolid coagulated mass.
- After a few minutes at room temperature, the semen begins to become thinner (liquefy) with some heterogeneous forms of coagulation
- As liquefaction continues, the semen becomes more homogeneous and quite watery
- The final stages present with small areas of coagulation and complete liquefaction takes about 15 minutes at room temperature in a normal setting. Some may take 1 hour to liquefy.
- If the semen appears clumpy, this may indicate a prostate problem of the prostate gland. The prostate gland is supposed to provide enzymes that cause the ejaculate to liquefy.
- If the semen appears runny, a problem may exist in the seminal vesicles. The seminal vesicles contribute proteins that cause the ejaculate to coagulate.
- Semen samples collected at home or by condom will normally have liquefied by the time they are delivered to the laboratory.
- The total volume of semen per ejaculate is about one-half to one teaspoon which is about 2ml (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.
- Some men have low ejaculate volumes but high sperm count, which does not affect the fertility. Others may have high ejaculate volumes and low sperm count. Low volume counts may indicate a low testosterone level. A very high volume count may indicate an infection.
- Conditions that may lead to low count or no count include retrograde ejaculation, where the sperm go backward into the bladder due to diabetes, prior surgery, or certain medications.
The sperm count is performed by careful analysis under a microscope. In a normal setting, a fertile male ejaculates about 60 million or more sperm per milliliter. How ever, there is a range of 20 to 150 million sperm per milliliter to be within the normal.
Fructose is present in large quantities in semen and is the main energy source for sperm. Fructose is produced only by the seminal vesicles. In conditions such as bilateral congenital absence of the vas, where there is absent seminal vesicles, the fructose in the ejaculate will be absent or very low. When there are no sperm counts in the ejaculate, this may indicate a problem. 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.
The pH of semen
The pH of seminal fluid lies between 7.2 and 8.0 and is measured in fresh samples of semen. It tends to fall as the sample ages. The pH of semen can occasionally be of value diagnostically to the doctor. Because of its high protein content, semen is a very effective buffer and it is difficult to alter its pH. However, severe infection particularly that of the prostate and seminal vesicles can increase the acidity of semen and a low pH may be helpful in making such a diagnosis. In men with bilateral congenital absence of the vas deferens where there is little production of and the pH is often reduced.
The Shape of sperm
A sperm that is shaped normally is more likely to fertilize the egg than one with a structural abnormality. In a normal setting, one must have at least 60 percent normally shaped sperm in a semen sample to be fertile. Abnormal sperm typically cannot move normally or penetrate an egg. An oval head is deemed to be normal but many shape and size variations can be seen in an ejaculate, and these include large, small or tapering heads.
- Amorphous heads are now known to be associated with chromosomal abnormalities
- Double heads are abnormal.
- Globozoospermia is when the sperm head lacks an acrosome and, as a consequence, the head becomes rounded
- When the mid piece is absent or not inserted into the head forming a so-called ‘broken neck’ it affects the shape.
- In others, a condition known as fibrous sheath dysplasia may also be present.
- Other abnormalities include tails that are short stubby, hairpin and angulated that affect the shape
- Double tails are also frequently seen in infertile samples. It’s perfectly normal to have some abnormally shaped sperm in every semen sample.
For the sperm to reach and penetrate the eggs, the speed and direction of the sperm is important. In the normal setting, when the sperm that have good motility, they can move through a woman’s reproductive tract at the rate of two inches per hour. At least 50 percent of the ejaculated sperm should have forward movement.
The Hamster egg penetration test (HEPT)
This is the test of the sperm’s ability to penetrate hamster eggs and is recommended when the male partner has a normal semen analysis and the woman has no obvious fertility problem, but pregnancy is still not occurring. In 1976, Yanagamachi and colleagues discovered that zona free hamster eggs could be penetrated by human sperm (Yanagamachi et al.1976), and Rogers and colleagues went on to develop this phenomenon as a test to predict the ability of a human sperm to fertilize an egg (Rogers et al.1979).This test is also performed prior to IVF to see if that technology will be successful for the couple. Essentially, the hamster test is a trial run of IVF but uses hamster eggs instead of a woman’s. The test is 90 % accurate.
Antisperm Antibody (ASA) test
Anti-sperm antibodies (ASAs) in semen belong almost exclusively to two immunoglobulin classes: IgA and IgG. IgM antibodies, because of their larger size, are rarely found in semen. Both classes can be detected on sperm cells or in biological fluids in related screening tests. When a man develops such antibodies against his own sperm, the antibodies attach themselves to the sperm’s surface and adversely affect the sperm’s movement and ability to fertilize an egg. It has been theorized that the antibodies occur when their sperm come into contact with their own blood such as during injuries or vasectomy. The body then develops the antibodies since sperm in blood are identified as foreign proteins which must be eliminated.