A
semen analysis evaluates certain characteristics of a male's
semenSemen is an organic fluid, also known as seminal fluid, that usually contains spermatozoa. It is secreted by the gonads and other sexual organs of male or hermaphroditic animals and can fertilize female ova...
and the
spermA sperm, from the ancient Greek word σπέρμα and and more commonly known as a sperm cell, is the haploid cell that is the male gamete. It joins an ovum to form a zygote. A zygote is a single cell, with a complete set of chromosomes, that normally develops into an embryo.Sperm cells contribute...
contained in the semen. It may be done while investigating a couple's
infertilityInfertility primarily refers to the biological inability of a person to contribute to conception. Infertility may also refer to the state of a woman who is unable to carry a pregnancy to full term...
or after a
vasectomyVasectomy is a minor surgical procedure wherein the vasa deferentia of a man are severed, and then tied or sealed in a manner such to prevent sperm from entering the seminal stream .-Types:...
to verify that the procedure was successful. It is also used in stud farming,
dog breedingDog breeding is the practice of mating selected specimens with the intent to maintain or produce specific qualities and characteristics.Dogs reproduce without human interference, so their offsprings' characteristics are determined by natural selection. Domestic dogs may be intentionally bred by...
and farm
animal breedingAnimal breeding is a branch of animal science that addresses the evaluation of the genetic value of domestic livestock...
.
Relation to fertility
The characteristics measured by semen analysis are only some of the factors in
semen qualitySemen quality is a measure of the ability of semen to accomplish fertilization. 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....
. One source states that 30% of men with a normal semen analysis actually have abnormal sperm function. Conversely, men with poor semen analysis results may go on to father children.
Collection methods
The most common way to collect a semen sample is through
masturbationMasturbation refers to sexual stimulation, especially of one's own genitals , often to the point of orgasm. The stimulation can be performed manually, by other types of bodily contact , by use of objects or tools, or by some combination of these methods...
, directing the sample into a clean cup.
A sample may also be collected during intercourse in a special type of
condomA condom is a barrier device most commonly used during sexual intercourse to reduce the likelihood of pregnancy and spreading sexually transmitted diseases . It is put on a man's erect penis and physically blocks ejaculated semen from entering the body of a sexual partner...
known as a
collection condom. Collection condoms are made from silicone or polyurethane, as
latexLatex refers generically to a stable dispersion of polymer microparticles in an aqueous medium. Latexes may be natural or synthetic. Latex as found in nature is a milky sap-like fluid within many plants that coagulates on exposure to air. It is a complex emulsion in which proteins, alkaloids,...
is somewhat harmful to sperm. Many men prefer collection condoms to masturbation, and some religions prohibit masturbation entirely. Adherents of religions that prohibit contraception, such as
CatholicThe word Catholic is derived from the Greek adjective , meaning "universal". In the context of Christian ecclesiology, it has a rich history and several usages. For some, the term "Catholic Church" refers to the church in full communion with the Bishop of Rome, made up of the Latin Rite and the 22...
ism, may use collection condoms with holes pricked in them.
A third option for collecting a sample is through
coitus interruptusCoitus interruptus, also known as withdrawal or the pull-out method, is a technique in which a man withdraws his penis prior to ejaculation during sexual intercourse, with the semen being ejaculated outside of and away from the vagina....
(withdrawal). With this technique, the man removes his penis from his partner near the end of intercourse and ejaculates into a cup.
Finally, if a blockage in the
vas deferensThe vas deferens , also called ductus deferens, , is part of the male anatomy of some species; they transport sperm from the epididymis in anticipation of ejaculation.-Structure:...
is suspected to impede fertility, semen can be taken directly from the
epididymisThe epididymis is part of the male reproductive system and is present in all male mammals. It is a narrow, tightly-coiled tube connecting the efferent ducts from the rear of each testicle to its vas deferens.-Regions:...
. Such a collection is called
per cutaneous epididymal sperm aspiration Percutaneous epididymal sperm aspiration is a technique used to determine sperm counts in the event of a possible blockage of the vas deferens. A small needle is inserted through the skin of the scrotum to collect sperm from the epididymis, where sperm are usually stored after production in the...
(PESA). Alternatively, the testicular tissue itself, instead of the sperm produced can be investigated. Then, the collecting method is called
TESE.
Tested characteristics
Examples of parameters measured in a semen analysis are: sperm count, motility, morphology, volume, fructose level and pH.
Sperm count
Sperm count, or
sperm concentration to avoid mixup, measures the concentration of sperm in a man's ejaculate, distinguished from
total sperm count, which is the sperm count multiplied with volume. Anything over 20 million sperm per milliliter is considered normal. Anything less is considered
oligospermiaOligospermia stands for low semen volume and is often mistaken for oligozoospermia, which means few "animals" in semen - a medical symptom of low sperm count affecting men. Oligozoospermia is now related to samples with less than 20 million spermatozoa per ml of ejaculate...
. A vasectomy is considered successful if the sample is
azoospermicAzoospermia is the medical condition of a male not having any measurable level of sperm in his semen. It is associated with very low levels of fertility.Azoospermia has two forms:...
. Some define success with rare non-motile sperm are observed (fewer than 100,000 per millilitre). Others advocate obtaining a second semen analysis to verify the counts are not increasing (as can happen with re-canalization) and others still may perform a repeat vasectomy for this situation.
The average sperm count today is around 60 million per milliliter in the Western world, having decreased by 1-2% per year from a substantially higher number decades ago.
Motility
The
motilityMotility is a biological term which refers to the ability to move spontaneously and actively, consuming energy in the process. It can apply to either single-celled or multicellular organisms. Motile marine animals are commonly called free-swimming...
of the sperm is evaluated.
WebMDWebMD Health Corporation is an American provider of health information services. It is primarily known for its public Internet site, which has information regarding health and health care, including a symptom checklist, pharmacy information, blogs of physicians with specific topics and a place to...
defines normal motility as 60% of observed sperm, or at least 8 million per millilitre, showing good forward movement. The
World Health OrganizationThe World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health...
has a similar value of 50% and this must be measured within 60 minutes of collection. A man can have a total number of sperm far over the limit of 20 million sperm cells per milliliter, but still have bad quality because too few of them are motile. However, if the sperm count is very high, then a motility of less than 60% might not matter, because the fraction might still be more than 8 million per millilitre. The other way around, a man can have a sperm count far less than 20 million sperm cells per millilitre and still have good motility, if more than 60% of those observed sperm cells show good forward movement.
A more specified measure is
motility grade, where the motility of sperm are divided into four different grades:
- Grade 4: Sperm with progressive motility. These are the strongest and swim fast in a straight line. Sometimes it is also denoted motility a.
- Grade 3: (non-linear motility): These also move forward but tend to travel in a curved or crooked motion. Sometimes also denoted motility b.
- Grade 2: These have non-progressive motility because they do not move forward despite the fact that they move their tails.
- Grade 1: These are immotile and fail to move at all.
Morphology
The
morphologyIn biology morphology is the form, structure and configuration of an organism.This includes aspects of the outward appearance as well as the form and structure of the internal parts like bones and organs...
of the sperm is also evaluated. With WHO criteria as described in the old manual of 1989, a sample is normal if 30% or more of the observed sperm have normal morphology. If morphology is evaluated using the Tygerberg strict criteria developed by Dr. Roelof Menkveld, Tygerberg Hospital, South Africa, and disseminated by Dr. Thinus Kruger from the same hospital, a sample is normal if 14% or more of the observed sperm have normal morphology.. The Tygerberg strict criteria for morpology assessment are recommended in the most recent WHO manual on semen analysis (WHO 1999).
According to the above references, morphology was developed as a predictor of success in fertilizing oocytes during invitro fertilization.
Volume
The volume of the sample is measured. WebMD advises that volumes between 1.0 mL and 6.5 mL are normal; WHO criteria specify that any volume greater than 2.0 mL is normal. Low volume may indicate partial or complete blockage of the
seminal vesicleThe seminal vesicles are a pair of simple tubular glands posteroinferior to the urinary bladder of males.-Anatomy:...
s, or that the man was born without seminal vesicles. In clinical practice, a volume of less than 2 mL in the setting of infertility and absent sperm should prompt an evaluation for obstructive
azoospermiaAzoospermia is the medical condition of a male not having any measurable level of sperm in his semen. It is associated with very low levels of fertility.Azoospermia has two forms:...
. A caveat to this is be sure it has been at least 48 hours since the last ejaculation to time of sample collection.
Fructose level
The level of
fructoseFructose is a simple monosaccharide found in many foods. It is a white solid that dissolves readily in water. Honey, tree fruits, berries, melons, and some root vegetables, contain significant amounts of the fructose derivative sucrose...
in the semen is measured. WebMD lists normal as at least 3
mg/
mL. WHO specifies a normal level of 13 μ
molThe mole is a unit of amount of substance: it is an SI base unit, and one of the few units used to measure this physical quantity. The name "mole" was coined in German by Wilhelm Ostwald in 1893, although the related concept of equivalent mass had been in use at least a century earlier...
per sample. Absence of fructose may indicate a problem with the seminal vesicles.
pH
The
pHpH is a measure of the acidity or basicity of a solution. It is defined as the cologarithm of the activity of dissolved hydrogen ions . Hydrogen ion activity coefficients cannot be measured experimentally, so they are based on theoretical calculations...
of the sample is measured. WebMD lists a normal range of 7.1-8.0; WHO criteria specify normal as 7.2-7.8. Acidic ejaculate (lower pH value) may indicate one or both of the seminal vesicles are blocked. A basic ejaculate (higher pH value) may indicate an
infectionAn infection is the detrimental colonization of a host organism by a foreign species. In an infection, the infecting organism seeks to utilize the host's resources to multiply, usually at the expense of the host. The infecting organism, or pathogen, interferes with the normal functioning of the...
. A pH value outside of the normal range is harmful to sperm.
Liquefaction
The
liquefactionIn physics, to liquefy means to turn something into the liquid state.Liquification can be a change from a gas to a liquid through condensation, usually by cooling, or a change from a solid to a liquid through melting, usually by heating or by grinding and blending with another liquid to induce...
is the process when the gel formed by proteins from the seminal vesicles is broken up and the semen becomes more liquid. It normally takes less than 20 minutes for the sample to change from a thick
gelA gel is a solid, jelly-like material that can have properties ranging from soft and weak to hard and tough. Gels are defined as a substantially dilute crosslinked system, which exhibits no flow when in the steady-state...
into a
liquidLiquid is one of the principal states of matter. A liquid is a fluid that has the particles loose and can freely form a distinct surface at the boundaries of its bulk material. The surface is a free surface where the liquid is not constrained by a container....
. An abnormally long liquefaction (more than 30 minutes at 37 24°C) time may indicate an infection.
MOT
MOT is a measure of how many million sperm cells per ml are highly motile, that is, approximately of grade 4, or sometimes also taking grade 3 into account. Thus, it is a combination of sperm count and motility.
With a straw volume of 0.5 milliliter per straw, the general guideline is that, for intracervical insemination (ICI), straws making a total of MOT40 is recommended. This is equal to 8 straws with MOT5, or 2 straws of MOT20. For intrauterine insemination (IUI), straws making a total of MOT10 is regarded sufficient. In WHO terms, it is thus recommended to use approximately 20 million grade 3+4 sperm in ICI, and 5 million ones in IUI.
Total motile spermatozoa
Total motile spermatozoa (TMS) or
total motile sperm count (TMSC) is a combination of sperm count, motility and volume, measuring how many million sperm cells in an entire ejaculate are motile.
Use of approximately 20 million grade 3+4 sperm in ICI, and 5 million ones in IUI may be an approximate recommendation.
Others
The sample is tested for
white blood cellWhite blood cells , or leukocytes , are cells of the immune system defending the body against both infectious disease and foreign materials. Five different and diverse types of leukocytes exist, but they are all produced and derived from a multipotent cell in the bone marrow known as a...
s. A high level of white blood cells (over 1 million per milliliter) may indicate an infection.
Abnormalities
- Aspermia
Aspermia is the complete lack of semen . Naturally, it is associated with infertility....
: absence of semen
- Azoospermia
Azoospermia is the medical condition of a male not having any measurable level of sperm in his semen. It is associated with very low levels of fertility.Azoospermia has two forms:...
: absence of sperm
- Oligospermia
Oligospermia stands for low semen volume and is often mistaken for oligozoospermia, which means few "animals" in semen - a medical symptom of low sperm count affecting men. Oligozoospermia is now related to samples with less than 20 million spermatozoa per ml of ejaculate...
: low number of sperm
- Asthenozoospermia
Asthenozoospermia is the medical term for reduced sperm motility.It decreases the sperm quality and is therefore one of the major causes of infertility or reduced fertility in men.-External links:* *...
: poor sperm motility
- Teratozoospermia: sperm carry more morphological defects than usual
Factors that influence results
Compared to samples obtained from masturbation, semen samples from collection condoms have higher total sperm counts, sperm motility, and percentage of sperm with normal morphology. For this reason, they are believed to give more accurate results when used for semen analysis.
How long the man has
abstainedSexual abstinence is the practice of voluntarily refraining from some or all aspects of sexual activity.Common reasons for practicing sexual abstinence include:*religious or philosophical reasons...
prior to providing the sample for analysis affects the results. Longer periods of abstinence correlate with poorer results - one study found that men with repeated normal results produced abnormal samples if they abstained for more than 10 days. It is recommended not to abstain for more than one or two days before providing the semen sample for analysis.
If the results from a man's first sample are subfertile, they must be verified with at least two more analyses. At least 2 to 4 weeks must be allowed between each analysis. Results for a single man may have a large amount of natural variation over time, meaning a single sample may not be representative of a man's average semen characteristics. In addition, sperm physiologist Joanna Ellington believes that the stress of producing an ejaculate sample for examination, often in an unfamiliar setting and without any lubrication (most lubricants are somewhat harmful to sperm), may explain why men's first samples often show poor results while later samples show normal results.
A man may prefer to produce his sample at home rather than at the clinic. The site of semen collection does
not affect the results of a semen analysis.
Measurement methods
Volume can be determined by measuring the weight of the sample container, knowing the mass of the empty container. Sperm count and morphology can be calculated by microscopy. Sperm count can also be estimated by kits that measure the amount of a sperm-associated protein, and are suitable for home use.
Computer Assisted Semen Analysis (CASA) is a catch-all phrase for automatic or semi-automatic semen analysis techniques. Most systems are based on
image analysisImage analysis is the extraction of meaningful information from images; mainly from digital images by means of digital image processing techniques...
, but alternative methods exist such as tracking cell movement on a digitizing tablet. Computer-assisted techniques are most-often used for the assessment of sperm concentration and mobility characteristics, such as
velocityIn physics, velocity is the rate of change of position. It is a vector physical quantity; both speed and direction are required to define it. In the SI system, it is measured in meters per second: or ms-1. The scalar absolute value of velocity is speed...
and linear velocity. Although many systems can give very accurate information about motility patterns of motile sperm, immotile sperm cannot accurately be distinguished from other cells, particles or debris without addition of staining. The first CASA systems in general cannot give reliable results for sperm concentration and proportions of sperm with different grades of motility, at least not in semen samples, where there are many other particles, cells and debris. Even when it comes to motility, most systems cannot give reliable results when the concentration of motile sperm leads to significant "crossed paths" - due to difficulties to decide if there were two sperm crossing each others way, or if there were for instance four sperm moving close to each other. Nowadays, there are CASA systems, based on image analysis and using new techniques, with near perfect results, and doing full analysis in a few seconds.
CASA Systems
SQA-V - The SQA-V, also known as the 'Sperm Quality Analyzer or Spermalite, is a high performance sperm analysis instrument used to test male fertility. It combines electro-optics, computer algorithms and video microscopy to provide a precise and accurate 75 second automated semen analysis. This device is manufactured by Medical Electronic Systems , who specializes in rapid, automated semen analysis. The main reason the SQA-V is a growing instrument among the semen analysis community is due to the speed, accuracy, and precision to run a semen sample. In addition, the SQA-V semen analysis eliminates inter-operator variables from the manual method, and still provides 16 clinical parameters including: Sperm Concentration, Rapid Progressive motility, Slow Progressive motility, Non-progressive motility, Immotility, %Normal Morphology, and more.
A study was conducted by the world renowned Cleveland Clinic comparing the SQA-V to the Manual method and the CASA device, presenting results favoring the SQA-V.
ISAS -
Integrated Semen Analysis System is a CASA system based on image analysis from the company
Projects i Serveis R+D S.L., also known as
PROISER.
PROISER was founded on 2004 by a team of CASA developers (
SCA 96,
SCA 98 and
SCA 2002) with more than 15 years in experience of seminal analysis by computer image analysis.
ISAS can be considered as the most complete and easiest-to-use system in market which, furthermore, works in different hardware and operating-system conditions, in order to adapt as much as possible to the needs of our users. Current computers and
AAVT technology allows a very good matching of spermatozoon, thanks to the tail and morphology analysis made at the same time as motility analysis. Only motility and concentration analysis give to the customers more tan 17 sperm parameters, but also
ISAS analyzes automatically stained morphometry, giving 15 parameters and DNA fragmentation analysis.
ISAS has been developed to be used in several species, from classical species like human, boar or bull to new research species like cod or some small rodents. There are a lot of publications and works in progress with
ISAS like . A list of last publications with this CASA system can be found on
publications with ISAS
Sperm Class Analyzer - The Sperm Class Analyzer, also known as 'SCA' from the company
Microptic S.L., provides fast, accurate and objectively repeatable results. This would be impossible to attain using traditional (subjective) methods. This CASA system has the following modules:
SCA Motility & Concentration: The system provides immediately and objectively detailed results of motility and concentration in a complete report.
SCA Morphology: Following a manual or automatic image capture, a precise morphological and morphometric analysis of each spermatozoid is provided in real time.
SCA DNA Fragmentation: Analysis of halo formation of the samples prepared for study of the DNA fragmentation provides detailed numerical data for each of the cells.
SCA Vitality: Automatically analyze the vitality of a sperm sample.
All this modules can be used with a motorized stage or link the database with any hospital system.
IVOS Sperm Analyzer - The Integrated Visual Optical System (IVOS) was developed by
Hamilton Thorne, the leading manufacturer of CASA systems since 1986. The IVOS is found in hospitals, universities, IVF clinics, pharmaceutical companies, contract labs, reproductive toxicology labs, veterinary clinics and animal breeding facilities around the world. The standard IVOS software may be used to analyze sperm of multiple species, with a specific program geared toward analysis of rat sperm. The IVOS is unique in that it is the only CASA system that integrates the optical system within the unit, so that an external microscope is not needed. The light source of the IVOS produces stroboscopic illumination to provide blur free sperm images. This stroboscopic light source is especially beneficial when utilizing the
IDENT fluorescent option on the IVOS as it allows the analysis of motile sperm under fluorescent illumination without adverse affect on sperm motility or velocity (this is not possible with continuous light fluorescent microscopes). Analysis using the IVOS IDENT provides highest accuracy of sperm counts in samples with a high degree of detritus, such as occurs in egg yolk extended samples or naturally in some species, such as rabbits. Samples are placed on a computer-controlled, heated stage which maintains samples at the proper analysis temperature and automatically moves to selected fields for analysis. A field of sperm are analyzed in just 0.5 second with a level of accuracy and repeatability unobtainable by visual assessment. Results calculated include count, concentration, motility, progressive motility, curvilinear velocity (VCL), straight line velocity (VSL), average path velocity (VAP), linearity (LIN), straightness (STR), amplitude of lateral head displacement (ALH) and beat cross frequency (BCF).
Custom software packages are available, such as Animal Breeder, Equine Breeder and Animal Motility, which provide additional features specific to the target industries. In addition, the
TOX IVOS is a complete system configured specifically for the inticacies of rat sperm analysis. Two automated morphology options,
Dimesnisons Strict Morphology (developed and validated by Dr. Thinus Kruger) and
Metrix user defined morphology are available. Another fluorescent option is
VIADENT, which permits the analysis of motility and viability on the same live sample.
"Our results suggest that the VIADENT option of the IVOS system is capable of a rapid, accurate and objective evaluation of both viability and motility parameters using large numbers of spermatozoa. Application of this technique in the industry may prove useful in the clinical assessment of fertilizing potential of equine spermatozoa."
CEROS Sperm Analyzer - Also from
Hamilton Thorne and built upon the same analysis algorithms and software interface as the IVOS, the
CEROS offers the same level of accuracy and reliability for sperm analysis. The CEROS uses an external negative phase contrast microscope for image visulaization and analysis. The system comes complete with motility analysis software, microscope, camera, computer and monitor. The CEROS is also compatible with both the Dimensions and Metrix morphology options and can be used for to analyze sperm from all species except rat. Both systems offer 4 levels of quality control as well as high-level security and audit trail for data inetgrity. A searacble list of publications featuring the Hamilton Thorne IVOS and CEROS CASA systems is found on
Connotea.
See also
- Semen quality
Semen quality is a measure of the ability of semen to accomplish fertilization. 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....
- Artificial insemination
Artificial insemination is the process by which sperm is placed into the reproductive tract of a female for the purpose of impregnating the female by using means other than sexual intercourse...
for more details of how semen parameters affects pregnancy rate
External links