Andrological Diagnostic Tests

Male infertility may be caused by a number of factors including:

• Problems with sperm production
• Blockage of the sperm delivery system
• Antibodies against sperm
• Injury to the testicle
• Problems relating to hormone production
• Anatomical problems
• Presence of a varicose vein around the testicle (varicocele)

all of which may affect sperm quality and quantity. Past illnesses, infections, various diseases and medications can also cause infertility.

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Male Infertility Tests

• Sperm Development
• Semen analysis
• White blood cells
• Sperm penetration assay (SPA)
• Antisperm antibody measurement
• Cryopreservation

Sperm Development

The development of normal, mature sperm is key in establishing male fertility and involves an interplay of several factors:

• An exchange of hormonal messages between the brain and the testicles
• A secretion of necessary reproductive hormones (testosterone) by Leydig cells and normal sperm development within Sertoli cells
• Normal transport of developing sperm from testicles to epididymis to vas deferens

The production of sperm is primarily regulated by three hormones:

• FSH
• LH
• Testosterone

In the male, pituitary hormones are responsible for maintaining the sperm production process. The pituitary gland, which is located at the base of the brain, secretes FSH and LH, the same hormones necessary for regulating the female's reproductive functions. FSH is responsible for stimulating sperm production in the testicles. LH stimulates the production of testosterone. Under the influence of Sertoli cells and specific hormones, immature sperm cells develop through several stages and eventually become mature sperm cells, called spermatozoa. Spermatozoa are not yet motile. They must pass through the epididymis, where after 18–24 hours, they gain motility (movement). After acquiring the ability to move, mature sperm are stored in the vas deferens until ejaculation.

One of the most important parts of an infertility work-up for men is to identify if a sperm problem exists. This may influence further testing of the woman or may indicate the need for the man to undergo treatment while the woman undergoes further testing.

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Semen Analysis

The semen analysis is the single most important test in the evaluation of a man's fertility. It provides information about a number of issues related to male fertility.

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What affects the ability of sperm to fertilize an egg?

A semen analysis is the study of a freshly ejaculated semen sample. This analysis measures the number of sperm present in the ejaculate (sperm count) and checks the shape and size (morphology) of sperm and their motility. The semen analysis is not an absolute test for fertility because it does not test certain important aspects of sperm function, such as whether sperm can actually penetrate the egg; however, it is very useful in initially determining if the cause of infertility is an obvious male factor.

Semen testing is performed using a fresh semen specimen within two hours of collection. This test is done in the physician's office or by a certified laboratory. The specimen is obtained through masturbation and is collected in a container provided by the physician. Semen for this analysis should not be obtained by interrupted intercourse or by use of an ordinary condom. Ordinary condoms contain substances that are toxic to sperm. If religious or personal practices prohibit masturbation or if the patient feels uncomfortable, the physician may suggest using a special condom designed for specimen collection that does not damage sperm. Feeling anxious about producing a specimen is common. Any questions or concerns should be discussed with a physician.

The information gathered during the semen analysis depends on proper collection of the specimen, as well as the skill of the technician or physician performing the test. Before testing, a standard period of sexual abstinence is recommended. Often, this is two to three days or the "usual" number of days between intercourse for the couple. This helps the physician obtain an idea of what the normal seminal fluid exposure is for the female partner. Because sperm counts and quality can vary, at least two or three samples will usually be obtained to establish a baseline.

Evaluation of semen is based on standards established for fertile males. When a patient has values below these limits, a male factor does not necessarily exist, but the probability is significantly increased. It is important to remember that, despite an overall low sperm count, men with high-quality sperm may still be fertile. High quality sperm is defined as having a high percentage of motile sperm with good forward movement. Sperm motility appears to be one of the most important factors in determining the fertilizing capability of sperm.

The following standard parameters are commonly used to define a normal semen analysis:

If the results of a semen analysis warrant additional testing, there are several diagnostic tests that may be used to establish a diagnosis.

In addition to standard semen analysis, there are other tests of semen and sperm. These can help your doctor discover whether there is an infection, determine the size and shape of sperm and measure the ability of sperm to penetrate an egg.

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White Blood Cells

During the semen evaluation, the presence of round cells will be assessed. Although difficult to distinguish by routine microscopy, these cells can be either early sperm forms or inflammatory cells known as white blood cells (WBCs). Special stains or antibodies can be used to differentiate early sperm from white blood cells in the semen. If pyospermia (an excess of these cells) is found, an evaluation for possible genital tract infections is undertaken because these cells can be associated with infection and/or inflammation. These infections may contribute to sperm damage but are often easily treated.

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Sperm Penetration Assay (SPA)

As previously mentioned, the semen analysis cannot determine if sperm are able to penetrate and fertilize an egg. One test that can provide important information about what happens when sperm reach the egg is the sperm penetration assay (also called the SPA or Hamster test). The SPA actually uses a specially prepared hamster egg. Usually, if a man has healthy sperm, his sperm will be able to penetrate, although not fertilize, this egg.

This test is commonly used in the following circumstances:

• For seemingly normal men with unexplained infertility
• In oligospermic men (men with very low sperm counts)
• As a screen for patients entering an in vitro fertilization or assisted reproductive program

Much of the reliability of the SPA depends on the techniques used to run the test. Since it was originally described for clinical use in 1979, the assay has undergone numerous changes to improve its accuracy. A positive result is generally reliable, but some false negatives do exist (for example, when the test shows a penetration defect, yet fertilization of the human egg occurs). Also, the correlation between failure to penetrate hamster eggs and failure to penetrate human eggs is not always exact.

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Antisperm Antibody Measurement

In some cases, the immune system may play a role in infertility. Normally, the immune system produces antibodies, or protein molecules that rid the body of foreign substances and diseases. Sometimes, the immune system fails to recognize what is a foreign substance, and it begins to attack or neutralize its own tissues. Antisperm antibodies (antibodies that attach to the surface of the sperm) may interfere with the ability of sperm to move, penetrate the woman's cervical secretions (mucus) or to fertilize an egg, depending on where the antibodies attach themselves. For example, when antibodies attach to the sperm's head, the sperm may be unable to fertilize an egg.

Men produce antisperm antibodies only when sperm come in contact with their blood (for example, after surgery or trauma to the testicles). This is because sperm develop in the testicles and are protected from exposure to the normal circulation of blood. If contact occurs, the body recognizes sperm as an invading substance and develops antibodies against them.

Antisperm antibodies can be measured in semen or blood by a variety of tests. The most widely used test to measure the presence of antibodies directly on sperm is known as the immunobead assay.

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