Semen Analysis | An Important Guide To Semen Analysis

The topic of infertility can be a sensitive matter. It’s important to get to grips with the basics, however, so you can feel prepared for what might lie ahead of you, if you’ve been referred to a specialist in reproductive medicine.

There are many male factors that can affect fertility.

Although it can feel embarrassing for many men, semen analysis is an important diagnostic test in the initial investigation of male infertility.

Related reading: Investigating Infertility – Preliminary Tests.

Are semen and sperm the same?

Semen is not the same as sperm. Sperm are the microscopic reproductive cells required to fertilize a female egg. The sperm carry the male’s genetic material, which will be passed on to the next generation during human development.

Sperm cells are carried in a mixture of fluid that is produced during sexual activity, or when a man is sexually stimulated. The fluid helps the sperm reach the egg after they’ve been ejaculated. This fluid is known as semen, or seminal fluid. Human semen is composed of a mixture of secretions from several components of the male reproductive tract.

To read more interesting sperm facts, read our article Sperm Facts – 8 Things You Won’t Read About On Wikipedia.

What is semen made of?

Semen analysis shows us that this thick fluid is made up of mostly water, with plasma and mucus, which is a lubricating substance.

Seminal fluid also contains a number of essential nutrients including:

• Calcium
• Zinc
• Fructose
• Glucose
• Lactic acid
• Magnesium
• Potassium
• Protein
• White blood cells.

These nutrients are needed to keep the sperm alive, provide energy and protect them from the harsh environment of the vagina as they make their journey to the female egg.

Related reading: Can You Get Pregnant From Precum?

Where does semen come from?

Surprisingly, the testes contribute only 5% of the volume of semen but, naturally, all of the sperm.

During ejaculation, the seminal fluid moves up through the epididymis and vas. Most of the fluid is produced by glands at the base of the bladder, particularly the seminal vesicles (about 70%) and the prostate (about 25%).

The first part of the ejaculate contains the highest sperm count with the best motility. In a semen analysis, the proper assessment of semen quality is essential in the diagnosis of several treatable disorders of male fertility. In many male factor infertility patients, however, no specific treatment is available to improve semen quality. In this case, semen analysis provides important information about the prospects for natural pregnancy and the use of assisted reproduction.

Is semen analysis an accurate test for fertility?

The semen analysis provides an indication of male fertility but is not an absolute test for fertility. It does not assess some important aspects of sperm function – for example, the ability of the sperm to locate and penetrate an egg. The finding of poor semen quality or abnormal sperm points to a reduced chance of pregnancy but natural conception might still occur in some cases. However, the more severe the semen defects, the lower the chances.

Routine semen analysis

For the semen sample result to be most valuable, proper collection of the specimen is essential. The semen analysis is performed on a fresh specimen, within 2 hours of collection. Before testing, a period of 2 to 5 days of abstinence from ejaculation is recommended. Feelings of anxiety about producing a specimen are common and should be discussed with the doctor or nurse.

Semen collection methods

The specimen is best collected by masturbation into a sterile container. This is most conveniently performed in the facility provided at the laboratory; collecting a sample at home, however, is acceptable, provided the sample is rapidly transported (within 1 hour) and kept at body temperature.

Semen collected by interrupted intercourse is not favored, as it risks the loss of the sample, particularly the first fraction of the ejaculate that might contain the highest number of sperm.

You should never collect semen in an ordinary condom, as condoms contain substances that kill sperm and will therefore affect the semen analysis results.

If religious or personal practices prohibit masturbation, a special condom (SCD), which does not affect the sperm quality, can be used instead.

The semen analysis

Laboratories vary widely in their ability to provide high quality analyses. Semen analyses are best performed in a specialised laboratory by staff with extensive experience, using the approved methods of the World Health Organization. Semen analysis test results are usually available within about a week after testing and, therefore, can provide useful information on reproductive health relatively quickly.

Analysis of the sperm sample includes the characteristics of the seminal fluid (semen pH and volume) and the characteristics of the sperm themselves, including the number of sperm (total sperm count or concentration), their movement (motility) and shape (sperm morphology).

Normal values of semen variables

The normal ranges for various parameters of semen quality and healthy sperm are shown below:

• Standard Tests Volume >2.0 ml.
• Sperm Concentration  >20 million sperm/ml.
• Sperm Motility  >50% with forward movement
• Sperm Morphology  >15% normal forms
• White Blood Cells  <1 million cells/ml.
• Sperm Antibodies (Immunobead Tests) <50% sperm with adherent particles.

Sperm count

It is important to recognize that an individual’s semen quality can vary considerably between samples – even in men with normal semen parameters. As a result, at least two, and occasionally three, semen analyses are needed, each several weeks apart, in order to get a good idea of an individual’s average semen quality.

It is well recognised that sperm concentration (the number of sperm present in a semen sample) can be adversely affected by illness, especially fevers, which might temporarily suppress sperm count in normal men for several months. In this case, the semen analysis should be delayed for several months.

A low sperm production is also referred to as oligozoospermia. Low sperm count is diagnosed when the number of sperm per millilitre of semen is fewer than 15 million, and can be the cause of male infertility. Low sperm counts can make it difficult, or less likely, for natural pregnancy to occur; conception, however, is still possible.

There can be a number of causes for a low sperm count, including:

• Hormonal imbalance
• Testicular surgery
• A genetic problem
• A structural problem – for example, the tubes that carry the sperm are blocked
• Genital infections, such as chlamydia or gonorrhoea
• Excessive alcohol or drug consumption or smoking
• Being overweight or obese.

The finding of no sperm within semen samples (known as ‘azoospermia’) suggests either an absence of sperm production or an obstruction to sperm outflow. It is most important that an azoospermic semen sample is spun down, to examine carefully whether the ejaculate contains even a few sperm. If a few sperm can be found (this is called ‘virtual azoospermia’), the technique of single sperm microinjection, also called IntraCytoplasmic Sperm Injection (ICSI), might be successful. In these severely infertile men, sperm might appear only intermittently, underlining the need for several semen analyses.

Sperm motility (movement)

Along with tests for low sperm count, samples collected can be tested for sperm motility, which is often impaired in men with ‘idiopathic’ (meaning the cause is unknown) poor sperm production. However, there are other important conditions that predominantly affect sperm motility, such as sperm autoimmunity – a condition that accounts for about 6% of male infertility. Semen analysis can show sperm with no movement (immotile sperm), which might be due to structural problems in the sperm tail or due to death of the sperm (necrospermia). Couples who experience this have an exceedingly low chance of natural fertility but ICSI can provide an alternative.

Sperm auto-immunity

The immune system produces antibodies, as part of the normal defense against foreign substances and organisms. Sperm are normally protected from exposure to the immune system. Some men, however, produce sperm antibodies, following surgery (eg vasectomy) or trauma to the testicles. In other men, there is no apparent cause for antibody development. The antibodies attach to the surface of the sperm and reduce their life span, impair sperm motility and ability to penetrate the partner’s cervical mucus. Finally, antibodies located on the sperm head might prevent the sperm fertilizing the egg.

Assessment for sperm antibodies is an essential initial test in infertility evaluation. The immunobead technique is a simple test that can be used to detect antispam antibodies in blood or semen.

Sperm morphology (shape)

Sperm shape is an important predictive indicator of sperm fertilizing ability. Compared with other species, the human male has a relatively small percentage of sperm showing a ‘normal’ morphology (actually defined as being ideally shaped), with as few as 15% normal forms being regarded as the lower limit of normal. Fertility declines as this percentage falls, particularly in men with ejaculates with less than 5% normal shaped sperm.

A normal sperm contain 3 distinct parts:

• Head, which contains the genetic material
• Mid piece, containing mitochondria, which generate the energy required for moving the sperm
• Tail, which propels the sperm forward, helping it to swim towards the egg.

Human sperm cells are definitely too small to be visible to the human eye; they measure about 0.0002 inches in length, or 0.005mm.

Sperm analysis requires great skill and experience. Sperm are specially stained and viewed under a microscope, with assessment of the head, middle and tail regions. Abnormally shaped sperm might have many defects, which can affect all regions of the sperm.

Other semen assessments

The percentage of sperm that are alive (sperm vitality) is also noted, because this declines in association with genital infections and disorders of sperm transport through the reproductive tract.

The white blood cell count is also a marker of possible genital tract infections. Even in the absence of a relevant history or symptoms, abnormal results might prompt an investigation of infection and could warrant a course of appropriate antibiotic therapy. Such infections can contribute to sperm damage and are easily treatable.

Home sperm test results

Home sperm test kits are available if you don’t feel comfortable going to see your GP; however, they have a number of limitations, compared with traditional laboratory tests; it is important to recognise this.

Semen testing at home might have some benefits, but it might not provide a complete semen analysis. For example, home tests might measure sperm count or semen volume, but might not measure sperm motility.

Sperm freezing

Sperm freezing is the most successful method of preserving a male’s fertility if he is not yet ready to have children. Men can freeze their sperm for future IVF treatment, or samples can be collected and frozen, to be donated for someone else’s treatment.

The freezing of sperm samples preserves the quality of the sperm and is just as successful in IVF treatment as freshly ejaculated sperm.

You might wish to consider freezing your sperm if you have various health conditions or if you’re undergoing treatment for health conditions that could affect your fertility.

There are no known risks of sperm freezing to patients’ or to future children’s health. However, not all sperm cells will survive the freezing and thawing process.

Semen analysis – conclusion

It is important to note that, even though normal ranges are given for various sperm parameters, they do not distinguish clearly between infertile and fertile semen. Couples with male factor infertility have a reduced chance of pregnancy. Nonetheless, even where couples have a sperm count of less than 5 million per millilitre, approximately 25% achieve a pregnancy within a two-year period. Such data shows that sperm count is only an imprecise measure of male fertility.

A man cannot generally be said to be sterile when moving sperm are present in the ejaculate. Factors including the duration of infertility, the frequency and timing of intercourse and the age and health of his partner are all important factors in the equation when couples are struggling to get pregnant.

Despite its deceptive simplicity, routine semen analysis requires attention to detail to maximise its diagnostic evaluation. It is a valuable tool in checking fertility and in discussing the likelihood of spontaneous pregnancy over a given period of time or the possible need for assisted reproduction.

Related reading: How To Increase Fertility After 40.