Semen routine
Semen examination is an important test to assess male fertility, not only for urologists but also for obstetricians and gynecologists. If the semen examination is clear that the husband is suffering from infertility, the wife can avoid a large number of tests.
Semen is the fluid that is discharged from the urethra when a man ejaculates during orgasm, and is a grayish-white, viscous liquid mixture consisting of sperm and seminal plasma. Spermatozoa are produced by the testes and mature in the epididymis. Seminal plasma is mainly a mixture of fluid secreted by accessory glands such as prostatic fluid, seminal vesicle gland and urethral bulb gland. Each component is normally in its own place and is mixed with each other during ejaculation to form semen.
Men enter puberty at the age of 9 to 12, when the testes begin to develop. At the age of 12 to 14, they are capable of discharging mature sperm, but the amount of semen is small, and at the age of 15 to 18, when genital development is complete, they can discharge mature semen.
Semen routine
1. Semen volume
The volume of semen discharged in one ejaculation is normally 2~6 ml, but less than 1.5 ml or more than 8 ml can easily lead to infertility. The reasons for low volume may include loss of part of the collection process, underdevelopment of the seminal vesicle gland or obstruction of the ejaculatory duct, low gonadal function due to reduced pituitary function, low gonadal function due to inflammation of the accessory gland, etc., which can be identified through component examination; the reasons for excessive volume include prolonged abstinence or strong secretion of the accessory gland, etc. Generally, the total amount of sperm is normal but will be diluted, resulting in reduced fertility.
2. Semen color
The normal semen is grayish white or milky white thick liquid when it is just ejected, and light yellow for those who have been abstinent for a long time. If it is yellowish green, there may be inflammation of the prostate gland or seminal vesicle gland, and if it is red, it may contain blood, which is seen in inflammation of the accessory gland and posterior urethra, and occasionally in patients with tuberculosis or tumors.
3. Semen coagulation and liquefaction
This is because semen contains semen coagulation proteins secreted by seminal vesicles. In the instant before ejaculation, the components of semen secreted by epididymis, prostate gland and urethral bulb gland mix with those secreted by seminal vesicles, and then coagulation reaction occurs quickly, which can make semen stay in the vagina for a longer time. Complete non-coagulation of semen can affect fertility and may be caused by obstruction of the ejaculatory ducts or congenital absence of the seminal vesicles.
The liquefaction of semen usually takes 5 to 20 minutes and is triggered by the liquefaction factor secreted by the prostate gland. If the liquefaction time exceeds 1 hour, it can affect the penetration of sperm into the female reproductive tract and cause infertility, usually due to low prostate function.
4. Semen odor
Semen has a special fishy odor, similar to that of chestnut blossoms, due to the oxidation of sperm ammonia, which is secreted by the prostate gland, and the lack of this odor indicates damage to prostate function, such as prostatitis.
5. Semen viscosity
The measurement is done on liquefied semen, using a semen viscosity tube (93 mm long, 0.672 mm inner diameter), the average time required to pass 0.5 ml of semen is 17 s. The simple test method is to use a dry glass rod in contact with semen and pull up the sticky wire when lifting the glass rod, the length of the sticky wire should be <2 cm. An increase in viscosity may be due to incomplete liquefaction due to prostatic lesions. Abnormal viscosity affects the motility of spermatozoa in semen.
6. Semen pH value
7.2~8.0, too high is mostly seen in acute epididymitis or epididymitis, too low is seen in chronic epididymitis, seminal vesicle gland or ejaculatory duct obstruction. pH value changes have an impact on sperm motility and metabolism, and are of some significance for disease identification.
7.Sperm density
A low sperm count or excessive sperm plasma can reduce sperm density and affect fertility. Low total sperm count may be caused by endocrine, infection, varicocele, immunity, cryptorchidism, syringomyelia, environment, genetics, etc. Excessive ejaculation may also lead to sperm reduction, while excessive sperm plasma may be caused by prolonged abstinence or strong secretion of the seminal vesicle gland.
8.Sperm motility
A level Fast linear forward motion
Class B slow or indefinite forward motion
Class C Non-forward motion
Level D inactive
Normal sperm A+B ≥ 32% or A+B+C ≥ 40%
9. Sperm viability score: Lanssa divided the sperm viability into 5 levels and multiplied by the percentage of live sperm to obtain the viability score, or viability index.
A sperm viability score of more than 150 is considered normal.
10. Sperm survival rate
The percentage of live sperm in semen is >58% in normal condition.
11.Sperm morphology
Normal morphology > 4%, less than 4% indicates testicular abnormality.
Factors affecting sperm viability, viability index, survival rate and morphology may include inflammation of the testes and each of the accessory gonads, congenital malformations, tissue cell damage due to physicochemical factors, drugs, toxins, nutritional status, etc.
12. Semen cells
Leukocytes: <5 cells/HP (high magnification view) increased in seminal vesiculitis, prostatitis and tuberculosis, etc.
Erythrocytes: 0~ Occasionally seen /HP. Increase is seen in seminal vesicle tuberculosis, prostate cancer, etc.
Seminal plasma biochemical examination
Seminal plasma is the medium of sperm, responsible for providing nutrition to sperm and assisting them to reach the site of fertilization. The various biochemical components of seminal plasma are secreted by specific accessory gonads, and quantitative testing of each component can determine whether the seminal plasma is normal and the source of the lesion. The major substances secreted by each gonad include
1. prostate.
Zinc: Zinc is a coenzyme for many enzymes in the body and is involved in a variety of metabolic activities. The prostate is one of the organs in the body that contains the most zinc, and the zinc content in normal human seminal plasma is 100 times higher than in plasma, reflecting the importance of zinc in maintaining functional sperm activity, but the specific principles of action are still not understood. The normal value of zinc in seminal plasma is ≥ 2.4 μmol in one ejaculation, below which suggests impaired prostate function.
Acid phosphatase: The role of acid phosphatase is to catalyze the hydrolysis of the phosphate bond and is present in all tissues throughout the body, with particularly high levels in the prostate. The level of acid phosphatase in seminal plasma can be used as an indicator to diagnose prostate pathology, but the relationship between its level and sperm quality is not known. The normal value of seminal plasma acid phosphatase is ≥ 200 U in one ejaculation.
Citrate: The high content of citrate in seminal plasma, almost all of which originates from the prostate, is used to regulate osmotic pressure and complex calcium ions, affecting the process of semen coagulation and liquefaction by changing the concentration of calcium ions. The normal value is ≥ 10 μmol in one ejaculation.
2. Seminal vesicles.
Fructose: fructose in seminal plasma provides energy for sperm and maintains sperm activity, while it parallels androgens and can indirectly reflect blood testosterone levels, and can be used to detect the function of seminal vesicles and testicular interstitial cells. Normal level of one ejaculation ≥ 13 μmol.
Prostaglandins: Some studies have shown that prostaglandins in seminal plasma can enhance sperm motility and inhibit immune attack in the female reproductive tract, and their levels are more difficult to detect and difficult to be used by clinical institutions.
3. Epididymis.
Neutral glycosidase: a specific marker enzyme of the epididymis, its alteration indirectly reflects changes in the function of the epididymis and also implies that sperm maturation in the epididymis is affected. Its normal value is ≥ 20mU in one ejaculation.
Post-coital test
The post-coital test can be used for suspected male infertility where no abnormality is found in the routine semen and seminal plasma biochemical examination. Infertility caused by abnormal interaction between cervical mucus and sperm in the mid-menstrual period needs to be diagnosed by post-coital test, which is manifested by low number and low activity of sperm in cervical mucus. The normal range is 5 or more sperm per high-powered field of view.
The cervical mucus is required to be taken within 1 to 6 hours after midmenstrual intercourse, and the sites of collection include the vaginal pool, the ectocervix, the middle of the cervical canal, the endocervix, and the uterine cavity. More than 5 spermatozoa in the endocervix and a cervical mucus pulling length of more than 6 cm are required to be normal.
Immunological examination
The autoimmune system may react to the antigens in semen when the blood-testis barrier is broken, and this test is to detect anti-sperm antibodies in the serum or semen.
1. Indications for the test.
(1) Unexplained infertility;
(2) Poor quality of post-coital test analysis;
(3) The patient has some kind of organic disease of the reproductive system, which is mild but may cause sperm immunity.
2, examination methods: including sperm agglutination test, sperm braking test, cervical mucus antibody test, etc. Positive results can be diagnosed as immune infertility.