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How Do You Examine Sperm?

Jun. 25, 2024

Basic items of semen examination


Routine examination of semen includes semen volume, appearance, liquefaction time, pH, viscosity, density, vitality, survival rate and morphological analysis. These items are most directly related to male fertility.


1. Semen volume

Due to individual differences, the amount of semen ejaculated by men is different, but it is normal for men to ejaculate 2-6 ml each time. Less than 1.5 ml and more than 8 ml are abnormal.


Usually, less than 0.5 ml is azoospermia; 0.5-1.5 is oligospermia; more than 6 ml is polyspermia.


(1) Azoospermia


It is common in patients with anejaculation or retrograde ejaculation, and is mainly manifested as male infertility;


(2) Oligospermia


There are many influencing factors. It is necessary to exclude human factors such as high frequency of sexual life and incomplete semen collection before suspecting disease problems, such as infection of accessory glands (prostate, seminal vesicles), incomplete retrograde ejaculation and incomplete development of seminal vesicles;


(3) Polyspermia


It is common in hyperfunction of accessory glands.

2. Appearance


Normal semen color is milky white or light yellow, which is related to the frequency of ejaculation. If a man does not ejaculate for a long time, the color of semen will turn yellow or light yellow. If he masturbates regularly or ejaculates during sex every week, the color of semen will turn white. If he masturbates excessively or has an uncontrolled sex life and ejaculates multiple times a day, the semen will become thin and transparent. Therefore, the color of semen is not only fixed, but is usually related to the frequency of ejaculation.


Abnormal semen has two types: clear and transparent and red.


(1) Clear and transparent semen


Generally contains a small number of sperm, which is common in men with azoospermia or oligospermia;


(2) Semen is brown-red or bloody


Commonly known as bloody semen, it is common in a variety of reproductive system diseases, such as seminal vesiculitis, prostatitis, stones, vas deferens damage and tumors, such as prostate cancer.


3. Liquefaction time


Sperm liquefaction refers to the fact that the semen just ejaculated is jelly-like. Usually, under the action of proteolytic enzymes and fibrinolytic enzymes secreted by the prostate, it will turn into a thin liquid in about 10-20 minutes. This process is called sperm liquefaction.


At room temperature, it will generally liquefy within 15 minutes. If it exceeds 30 minutes, it is called delayed liquefaction; if it exceeds 60 minutes, it is called non-liquefaction.


There are many reasons for semen non-liquefaction, such as prostate dysplasia, inflammation, resulting in increased coagulase secretion by the seminal vesicles or reduced fibrinolytic enzyme secretion by the prostate, zinc and magnesium deficiency, unhealthy lifestyle, etc.


4. pH


pH refers to the pH of semen. Normal semen pH7.2 is the lower limit and is an important indicator for semen quality analysis.


Semen is a mixture of accessory gland secretions, with 65% of seminal vesicle secretion and pH 7.8; 34% of prostatic fluid and pH 6.2; and 1% from the epididymis and bulbourethral glands. The final pH after the three are mixed is 7.4.


pH reflects the external environment of sperm and the balance of these three fluids. Too high or too low will affect the quality of semen, such as sperm motility and capacitation: sperm vitality and motility parameters are best at pH7.2-8.0, and decrease at 5.2-6.2.


Many factors can cause changes in pH. There are many factors that affect the pH of sperm, such as inflammation in men, urinary tract infection, or malnutrition, long-term sitting, and special occupations, which will affect the pH of semen.


5. Viscosity


Viscosity refers to the high viscosity of semen fluid after liquefaction.


Compared with sperm in high-viscosity semen and normal semen, only the swing amplitude of the sperm tail is significantly different, and there is no significant difference in other movement parameters.


In addition, the viscosity of semen has little effect on fertility and is not one of the major influencing factors.


6. Sperm density


The normal value of sperm density is: greater than 15x10^6 /ml. If it is lower than this value, it is oligospermia. Sperm density ≥250×10^6/mL is defined as polyspermia.


The indicator of sperm density needs to be combined with semen volume and other indicators.


When looking at some semen parameters, such as deformity rate, vitality, etc., it is necessary to calculate based on the total amount of sperm. Sometimes, even if the vitality is low and the deformity rate is high, but the total amount of sperm is large, the total number of normal sperm is not small.


Common causes of low sperm density include testicular spermatogenesis and endocrine factors.


(1) Low testicular spermatogenesis


Congenital testicular spermatogenesis disorders, chromosomal abnormalities, AZF microdeletions, and acquired testicular function damage can all lead to low sperm density.


(2) Endocrine factors


Insufficient testosterone secretion caused by various factors can also lead to low sperm density. In addition, obstructive factors can also cause it.


Of course, the higher the sperm density, the better. If the sperm density is too high, the nutrient fructose in the semen will be quickly depleted, resulting in poor sperm motility and low survival rate.


7. Sperm motility


Motile type (PR): active sperm, linear or large range movement;


Non-motile type (NP): inactive sperm;


Completely immobile type (IM): completely immobile sperm.


In some reports, you will also see grading indicators such as a, b, c, and d:


Grade a: fast forward movement or large circular movement;


Grade b: slow or sluggish forward movement or small circular movement;


Grade c: non-forward movement;


Grade d: no movement;


The two grades have a corresponding relationship: PR is a+b, NP is c, and IM is d.


The PR of normal fertile men is ≥32%, and PR+NP is ≥40%.


If the sperm motility is reduced, the a-grade sperm should be <32%, and a+b <50%, which is asthenozoospermia. The cause of this disease is complex and is most likely related to inflammation of the accessory glands or epididymis.


8. Sperm survival rate


The sperm survival rate is expressed as the percentage of live sperm, including active and inactive sperm.


The sperm survival rate of normal men should be ≥58%.


Sperm survival rate is not equal to sperm activity rate. Some sperms are still alive without moving, which generally indicates that the tail of the sperm is defective. Its own genetic material may not have changed. Such sperms can still be used for single sperm oocyte injection.


Causes of low sperm survival rate


Low sperm survival rate is mainly caused by bad living habits, endocrine disorders or orchitis.


(1) Bad living habits: If you often stay up late or smoke and drink, it may lead to a decrease in sperm survival rate.


(2) Endocrine disorders: Endocrine disorders may cause a decrease in androgen levels in the body, which will affect sperm formation and thus cause a low sperm survival rate.


(3) Orchitis: Orchitis is generally caused by bacterial infection, which may cause pain in the testicles and also lead to a decrease in sperm survival rate.


9. Sperm malformation rate


Malformed sperm will not cause fetal malformation. Teratozoospermia is mainly related to the probability of pregnancy, but has little to do with the nature of sperm (genetic material). This is just like the fact that a person's appearance has no direct relationship with his or her essence. Whether a person is good-looking or not cannot indicate whether he or she is healthy, and it cannot be said that a person with an unattractive appearance has poor health.


Sperm deformity rate refers to the ratio of abnormal sperm morphology. Normal sperm morphology ≥ 4% is considered normal.


Factors that cause increased sperm deformity rate


(1) Unhealthy lifestyle: Long-term smoking, drinking, etc. can affect the morphology of sperm and lead to a high sperm deformity rate.


(2) Environmental factors: Frequent contact with heavy metals such as lead and manganese, and contact with pesticides such as organic mercury pesticides and organic phosphorus pesticides can lead to a high sperm deformity rate.


(3) Physical factors: If the testicles and epididymis are exposed to external radiation for a long time, it can lead to a decrease in sperm count, decreased activity, and a high deformity rate.


(4) Drug factors: Long-term or high-dose use of glucocorticoids, androgens and estrogens, and the use of alkylating agents (such as cyclophosphamide), antimetabolites (such as cytarabine) and alkaloids (such as vincristine) by cancer patients may lead to low sperm count and high sperm deformity rate.


(5) Disease factors: Reproductive tract infection, varicocele and other diseases can also lead to high sperm deformity rate. For example, genital tract pathogenic microbial infection (such as mycoplasma and chlamydia infection) can affect the morphology of sperm, resulting in high sperm deformity rate; varicocele can cause venous blood reflux obstruction, metabolic toxins accumulation, local scrotal temperature rise, etc., thereby affecting testicular function and leading to high sperm deformity rate.


However, a high deformity rate does not mean that there is no possibility of fertility, because the morphology of deformed sperm varies, some are severely deformed, and some are at the critical level. Moreover, this analysis is subjective, and different people or different laboratories may report different results. It is normal for the results to fluctuate within a certain range.

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