According to the reference values established by the World Health Organization (WHO), a fertile male must have at least 15 million spermatozoa per milliliter of semen. The progressive motility of the sperm should be more than 32% and the morphology is normal (without anomalies) should be more than 4%.
The morphology of the spermatozoa is a characteristic that is studied in the spermiogram (it is the same as the seminogram) to see if there are abnormal spermatozoa in the semen, in what quantity they are found and what alterations they have.
When a seminal sample does not reach the minimum values of normality in morphology, it is said to present teratozoospermia.
It is important to bear in mind that all men produce abnormal spermatozoa and that a large part of the spermatozoa in a semen sample considered normal have an abnormal shape and this does not imply infertility.
-How do we know if it is normal?
In order to study the morphology of the male gametes (spermatozoa), it is necessary to fix a small sample of the total ejaculate on a slide, which implies the death of the spermatozoa. This prevents this sample from being used after evaluation, but it will serve as a representation of the rest of the total seminal sample.
Once fixed, a biological staining is performed, such as hematoxylin-eosin: eosin is attached to the electropositive elements of the cell and has a pink coloration and hematoxylin is attached to the electronegative molecules of the spermatozoa, obtaining a coloration in blue tones.
The staining of the different structures allows a better observation under the microscope by increasing the definition of the membrane: in order to assess the shape of a spermatozoid, its three main structures are observed: head, intermediate piece and tail.
The head of the sperm must be oval and smooth, from 5 to 6 micrometers long and from 2.5 to 3.5 micrometers wide. The acrosome (which is a small deposit located at the apical end of the head of the spermatozoid and contains hydrolytic enzymes, mainly hyaluronidase, whose mission is the progressive separation of cells from the cluster or layer surrounding the oocyte, by hydrolysis of the polymer that holds them together, hyaluronic acid.
Another of the enzymes contained in the acrosome is acrosine, a hydrolytic enzyme that breaks the zona pellucida of the oocyte and allows the entry of sperm aided by the movement of the flagellum), must comprise 40-70% of the volume of the head, and if there are vacuoles must be scarce and occupy less than half the volume of the head because if they are numerous or large can mean that the DNA is damaged.
The middle piece or neck, as its name suggests, is located between the head and the flagellum, and is an area a little wider than the base of the tail. Its function is paramount because it houses the mitochondria, considered the motor of sperm movement, as they are responsible for generating energy.
The flagellum or tail is made up of the same structural molecules responsible for the correct distribution of chromosomes in mitosis and meiosis, with which an irregular flagellum will reflect problems in the distribution of chromosomes, and above all, its movement will not be able to compete with the advance of a normal spermatozoon.
The evaluation of the stained sperm sample consists of counting the number of normal and abnormal spermatozoa. Generally, 200 sperm are valued and then the percentage of normal-shaped sperm is estimated.
The alterations in morphology can have a genetic origin, hence the importance of presenting a correct morphology. A sperm whose genetic information, half of the future embryo, is not well coded and organized will not give rise to a viable embryo.
Normally shaped sperm advance faster and more adequately. In contrast, most abnormal sperm are immobile or have slow motility. When a spermatozoid is abnormal: they may present an abnormal head, intermediate piece and/or tail. Thus, there may be the following abnormalities:
Head alterations: sperm without head, small head, amorphous, round, elongated, large head (ballozoospermia), pear-shaped (pyriform), large acrosome, small acrosome, no acrosome, many vacuoles, large vacuoles or two headed.
Tail alterations: sperm without tail, tail rolled up, short, long, bent or double tail.
Alterations of intermediate piece: sperm without intermediate piece, with a curvature, asymmetrical, thickened, thin, irregular or with a protuberance of a size greater than one third of the head area.
There are very clear alterations, such as the duplication or absence of these structures, sperm with double tail, microcephalic or macrocephalic, which can never give rise to a viable embryo in a natural way.
According to WHO criteria, a value equal to or greater than 4% of spermatozoa with normal morphology is considered to be within normal values. If the rate of abnormalities is greater than 96% we are dealing with a case of teratozoospermia.
There is another criterion for the analysis of the slightly stricter morphology, Kruger’s criterion or morphology, according to which the limit of normality is 14%, that is to say, a sample with more than 86% of its abnormal spermatozoa will be considered to have teratozoospermia.
-What treatment it has:
This will depend on the cause, whether it is genetic or acquired, caused either by hypogonadotropic or hypergonadotropic hypogonadism. A man whose sperm show a very abnormal morphology, that is, he suffers from teratozoospermia, may have greater difficulties in achieving pregnancy in a natural way, or even impossible in some cases.
Although teratozoospermia is not one of the most serious seminal problems, sometimes it will be necessary to resort to assisted reproduction to achieve a viable pregnancy, especially in the most serious cases.
Depending on the degree of affection and other factors affecting fertility, both in men and women, the specialist will determine which is the most suitable reproductive treatment, whether artificial insemination or in vitro fertilization.
-Complete seminal analysis:
It represents the most complete evaluation for ejaculated sperm. Abstinence of 2 to 5 days is required for an optimal initial evaluation. Typically 2 to 3 seminal analyses are required to obtain a true initial evaluation since sperm concentration can vary significantly.
Seminal results are a central component of male fertility testing. It is almost always the first fertility test a man is asked to take. Although useful, it should be noted that the values of a normal seminalysis are only guidelines and do not guarantee the absence of major problems with male factors.
The World Health Organization (WHO) has defined male infertility based on the concentration of sperm in semen. While concentration is useful, many other clinically important factors are measured. Most male fertility specialists believe that semen analysis is only a simple test and that future tests will allow for more extensive sperm testing.
-WHO guidelines for semen analysis:
Volume: 1.5 ml to 5.0 ml
Liquefaction: After ejaculation, the semen presents a coagulated state and needs to be liquefied in order to be studied. Under normal conditions, the semen is completely liquefied 60 minutes after ejaculation.
Viscosity: If the sample is very viscous, it may be due to prostate dysfunction.
Volume: The normal volume of an ejaculate after 3 to 5 days of abstinence is approximately 1.5 ml. A lower volume is called hypospermia.
Color: The usual color of semen is opalescent white, slightly yellowish. In cases where the colour is altered, it is advisable to study the possible causes.
pH: The value must be above 7.2. Lower values could indicate azoospermia (absence of sperm) or chronic inflammatory processes.
Concentration (number of sperm present per ml of ejaculate): more than 15 million/ml, or 39 million in the total ejaculate. Otherwise, it is called Oligozoospermia.
Vitality (percentage of sperm with movement): the percentage of live sperm must exceed 58%. If it were lower we would speak of Necrozoospermia.
Forward progression (of the movement of spermatozoa, the force of their movement forward): the percentage of mobile and progressive spermatozoa (moving motile) is evaluated. Progressive motives must exceed 32%, otherwise it is called Astenozoospermia.
Morphology (percentage of sperm with normal shape): 4% or more normal shapes (WHO criteria) or 14% or more (Kruger’s strict criteria). If it is below this value it is called Teratozoospermia.
Presence of red or white blood cells: minimal
No hyperviscosity (thickening of seminal fluid)
Leukocytes: If the concentration of leukocytes is greater than 1 million per ml of sample, it may indicate an infection (leukocytosis).
Antisperm antibodies: reflects the amount of sperm attached to other cells or particles. If more than 50% of sperm are united, it may reflect an immune problem, are antibodies on the surface of the sperm, and is clinically useful information.
The causes of antisperm antibodies are caused by rupture of the hemato-testicular barrier and this includes lesions in the testicle, infection, surgical procedures such as vasectomy, specifically, antisperm antibodies are IgA and IgG type.
The number of women who are going to produce antisperm antibodies is very low, but it can occur in the following cases: gynecological infections or inflammations of the genital tract. SSAs hinder the progressive mobility of sperm and interfere with their encounter and interaction with the egg.
-Strict morphology of Kruger’s spermiogram
This test looks at the sperm shape (morphology – shape) in a much more critical and profound way than the WHO routine method. It is considered to have clinical significance when deciding between IUI (intrauterine insemination) and IVF (in vitro fertilization). It is important to recognize that an abnormally low number of «normal spermatozoa» is not associated with a high rate of congenital malformations (abnormality in the product of gestation).
-Other studies of interest:
Retrograde seminal analysis: this test is used when patients no longer ejaculate through the tip of the penis. In some situations such as spinal cord injuries, some drugs, or after surgery, ejaculation flows backward (retrograde) into the bladder. This process involves removing sperm from the bladder that can then be washed and used for insemination or IVF.
Post-ejaculation Urine. This is a diagnostic method to detect retrograde ejaculation. This simple process is only useful in patients who are able to urinate. The patient evacuates into a sample cup after ejaculation and the sample is evaluated for the presence of sperm. Sometimes a catheter is required if the patient is unable to empty his or her bladder completely.
Viability tests: A special stain is used to determine if sperm is viable (alive) when there is an absence of motility (movement) and includes progressive and nonprogressive motility, should be greater than 40%.
XY relationship stain: A specialized process is used to determine the relationship between male (Y) and female (X) sperm. This provides useful clinical information for gender preselection (sex selection).
High-speed centrifugation: When no sperm are observed in the ejaculation, the sample is rotated in a centrifuge to observe the presence of even a few sperm. Any sperm found is potentially useful for IVF and may provide new hope for infertile men.
Sperm DNA Integrity Analysis (also called SCSA: Sperm Chromatin Structure Assay ): this test is to observe inside the sperm the degree of DNA binding after applying external forces. If the DNA fragments easily, it has been linked to recurrent abortions.
Sperm penetration assay (SPA): The SPA tests whether a man’s sperm can penetrate a female egg. Egg penetration is necessary for fertilization to occur. This test is usually ordered when low IVF (IFV) fertilization rates are found without other explanation.
The technique called ICSI (intracytoplasmic sperm injection) is an assisted reproductive practice included in the IVF treatment that has made it possible to successfully achieve pregnancy in couples diagnosed with a severe male factor.
The male must provide a semen sample or perform a testicular biopsy, if necessary, to extract and select the best sperm that will be used for the fertilization of the oocytes and consists of the microinjection of a single sperm or spermatozoon in the cytoplasm of the oocyte.
Circumstances in which ICSI may be appropriate include: When the sperm count is very low, when sperm cannot move properly or are otherwise abnormal, when sperm have been surgically removed from the epididymis or testicles, in the urine or after electroejaculation, when there are high levels of antibodies in the semen, when there has been previous fertilization failure using conventional IVF.