Semen quality
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Semen_quality".

Semen quality is a measure of the ability of semen to accomplish fertilisation. Thus, it is a measure of fertility in a man. It is the sperm in the semen that are of importance, and therefore semen quality involves both sperm quantity and sperm quality.

Tests

Semen analysis

Main article: Semen analysis

A semen analysis typically measures the number of sperm per milliliter of ejaculate, and analyzes the morphology (shape) and motility (ability to swim forward) of the sperm. Also usually measured are the concentration of white blood cells, the level of fructose in the semen, and the volume, pH, and liquefaction time of the ejaculate.¹²

A number of factors may influence the accuracy of semen analysis results, and results for a single man may have a large amount of natural variation over time.³ For this reason, a subfertile result must be confirmed with at least two further analyses.⁴

Hamster zona-free ovum test

Main article: Hamster zona-free ovum test

A man's sperm are mixed with hamster eggs that have had the zona pellucida (outer membranes) removed, and the number of sperm penetrations per egg is measured. The human sperm does not fertilize the hamster eggs.⁵ A negative result on the hamster test correlates with a lower probability of the man's partner becoming pregnant.⁶

Sperm chromatin assay

Chromatin is the complex of DNA and protein that make up chromosomes. If a large percentage of a man's sperm (greater than 30%) have damaged chromatin, his chances of impregnating a partner are significantly reduced, and if he does impregnate his partner, she faces an increased risk of miscarriage. The portion of a man's sperm with damaged chromatin may be determined with a Sperm Chromatin Structure Assay (SCSA).⁷

Cryopreservation

When performing cryopreservation of semen, it is the sperm quality after reviving the sample that is of importance, because many sperm cells die in the process.

To be of use in assisted reproductive technology, the sample should after thawing have more than 5 million motile sperm cells per ml with a good grade of motility. If the grade of motility is poor, 10 million motile cells per ml is required.⁸

Bad freezers

In 10-20% of all men, the semen doesn't endure cryopreservation.⁸ The cause is unknown. It does not necessarily mean an otherwise bad semen quality.

Sperm Washing

When a sperm sample is prepared for intrauterine insemination, it is washed at a facility such as a fertility clinic or a sperm bank. Some sperm does not survive the washing process, as is also the case when freezing the sperm. ⁹

Factors

There are many factors that influence the sperm quality. If exposure to any of them has happened, it might take up to 3 months before the sperm quality is up to normal again, because that's how long time spermiogenesis takes.⁸

Masturbation or intercourse

Sperm samples obtained via sexual intercourse contain 70¹⁰-120¹¹% more sperm, with each sperm having a slightly higher¹² motility and slightly more normal¹² morphology, compared with sperm samples obtained via masturbation. Sexual intercourse also generates an 25-45%¹² increase in ejaculate volume, mainly by increased prostate¹³ secretion.

This intercourse advantage is even greater for men with oligospermia.¹²

However, the single factor or factors for the intercourse advantage have not yet been isolated. It can not be explained by presence of visual perception of physical attractiveness alone during stimulation,^{12 14}, although there may be a slight correlation.¹⁵ Neither does any substantial fluctuations in sex hormones explain the intercourse advantage. ¹³ It is hypothesized that sexual intercourse subdues an inhibition from the central nervous system¹², but what, in turn, is the subduing factor is still not completely known. Stress to achieve ejaculation is suggested, as a shorter duration of stimulation before ejaculation decreases semen quality.¹⁶

Heat

Sperm are heat-sensitive, and cannot endure too high temperatures. The body has compensatory mechanisms, like the cremaster muscle relaxing and letting the testicle further away from the warm body, sweating and a Countercurrent exchange of blood cooling inflowing blood. However, despite the compensation of the body, there are activities that should not be performed too often, in order of preventing infertility due to heat;

• sauna sessions⁸
• bathing long time in hot water⁸
• Long-time tanning bed sessions⁸
• Tight⁸ and airtight trousers and underwear, since it hampers the sweating mechanism.

Fever also raises the body temperature, which can strike sperm quality.

In the same way, sperm quality can be lower in the summer.⁸

Physical trauma

A blow from outside doesn't affect the sperm quality of already produced sperm cells. Furthermore, the testes are well protected in the scrotum, for example by the tunica vaginalis, making the testes slide away from external pressure rather than being malformed from it. However a hard enough hit can close or crush the capilliaries that produce sperm, resulting in permanent or temporary partial or total inability to produce sperm in the affected testicle.

Chemicals

There is suspicion that many toxic substances, including several types of medication and hormones, and also constitutents of the diet, influence sperm quality⁸. While a few chemicals with known effects on fertility have been excluded from human consumption, we cannot know if others remain undiscovered.

Medication

• Depo-Provera, Adjudin, and gossypol are examples of substances used as male contraceptives or in chemical castration. Recent studies have found that THC present in marijuana can confuse the movements of intact sperm, reducing their ability to achieve fertilization.¹⁷¹⁸

• Selective serotonin reuptake inhibitors (SSRI) may cause low sperm count.¹⁹

Hormones

• Anabolic steroids abuse and abuse of other hormones can reduce sperm quality. Changes in hormone homeostasis affect the spermatogenesis.

The body also has natural variations in hormone concentrations, giving sperm quality natural fluctuations as well.⁸

Diet

• Coffee and alcohol lowers the sperm quality. However, the influence is probably minor.⁸

• Red wine and soy sauce may theoretically decrease sperm quality due to content of isoflavones, a type of phytoestrogens.²⁰ In theory, exposure to high levels of phytoestrogen in men could alter their hypothalamic-pituitary-gonadal axis. However, studies have shown that such a hormonal effect is minor. Isoflavones supplementation has no effect in sperm concentration, count or mobility and show no changes in testicular or ejaculate volume.²¹²²

Other chemicals

• Gossypol present in crude cottonseed oil (and potentially the organ meats from animals poisoned with it²³) has been associated with reduced sperm production. Misuse of anabolic steroids can cause testicular atrophy and reduced fertility.

Last ejaculation

How long the man has abstained prior to providing a semen sample correlates with the results of semen analysis and also with success rates in assisted reproductive technology (ART).

Both a too short period of time since last ejaculation and a too long one reduces semen quality.

• A period of time of less than one day reduces sperm count by at least 20%. ²⁴

• Longer periods of abstinence correlate with poorer results - one study ²⁵ found that men with repeated normal results from semen analysis produced abnormal samples if they abstained for more than 10 days. Another study²⁵ found that couples where the man had abstained for more than 10 days before an intrauterine insemination (IUI) had only a 3% pregnancy rate.

Environment

For semen that has been ejaculated, the quality deteriorates with time. However, this lifetime can be shortened or prolonged, depending on the environment.

Outside body

Sperm outside of the body generally has a life expectancy which is considered to depend on pH, temperature, presence of air and other factors, and is unpredictable but smaller than the life expectancy inside the human body.^{citation needed} For instance, sperm donors who collect the sample outside the clinic are advised to have handed in the sample before one hour from collection, and to keep them in, if not at body temperature, then at least at room temperature.²⁶

In a non-harmful environment outside the body, such as in a sterile glass container¹² the number of motile sperm decreases with approximately 5-10%¹² per hour. In contrast, in a latex condom, the quality decreases with 60-80%¹² per hour, rendering the sample unusable in not too long time.

In female

The environment in the uterus and fallopian tubes are advantageous. A pregnancy resulting from sperm life of eight days has been documented.²⁷²⁸²⁹

Home or in clinic

The sperm quality is better if the sample is collected at home than in the booths in the clinics ³⁰. Collecting the sperm at home gives a higher sperm concentration, sperm count and motility particularly if the sperm is collected via sexual intercourse.³⁰

Others

Smoking lowers the sperm quality. However, the influence is probably minor.⁸ Long-term stress is also suggested.⁸

Regarding diet, malnutrition or an unhealthy diet can lead to e.g. Zinc deficiency, lowering sperm quality. Theoretically, a diet with low glycemic index would increase semen quality by providing an even supply of blood sugar, which is the major energy source for sperm cells. However, no trials have yet investigated the role of glycemic index on semen quality.³¹

Sperm quality is better in the afternoon than in the morning.³²

Lack of exercise, as well as excessive exercise, are minor factors.

A longer duration of sexual stimulation before ejaculation slightly increases sperm quality.³³

Dehydration, especially long term, will result in lower sperm count, quality and mobility^{citation needed}. The body needs to choose between "slowing down" reproductive organs as they are not necessary for daily life, or being able to reproduce.

Having a mobile phone in talk mode in the pocket, like when using handsfree, has been suggested to be a risk if often used in the long-term,³⁴ but the subject is disputed.

References