Article 72: Semen Biochemical and Microbiological Examinations and Testicular Volume Measurement

◇A Guide to Caring for Your Husband's Health as a Good Wife◇

Next chapter: CHANG JIAN BING DE ZHI LIAO YU TIAO YANG

Treatment and recuperation of common diseases

What does a semen biochemical test include?

The most commonly performed biochemical tests on semen are fructose, acid phosphatase, citric acid, protein, trace elements, and lactate dehydrogenase X.

When performing biochemical tests on semen, the semen sample should be placed in a water bath at 35-37℃. After liquefaction, take 12-15 ml and centrifuge for 15 minutes. Take the upper seminal plasma for biochemical analysis.

1. Fructose determination: Generally, the resorcinol method is used, and the normal value is (256±104) mg/dL. Fructose is mainly secreted by the seminal vesicles and is the main source of energy metabolism for sperm, and is related to sperm motility. Zero fructose should raise suspicion of seminal vesicle absence. Fructose content decreases when there is inflammation of the seminal vesicles. In addition, fructose content decreases in cases of androgen deficiency and old age, while it is higher in seminal plasma in diabetic patients.

2. Acid phosphatase: Measured using the β-glycerophosphate method. The normal value is (882±412) Brunner units/mL. This enzyme mainly originates from the prostate gland. It is related to sperm motility and metabolism. In prostatitis, the acid phosphatase content in seminal plasma decreases; in early prostate cancer or benign prostatic hyperplasia, the acid phosphatase content is often increased.

3. Citric acid: The normal value is (56±20) mg/dL. It mainly comes from the prostate and regulates the concentration of calcium ions in semen, affecting semen liquefaction. It also acts as an activator of prostatic acid phosphatase, thus affecting sperm motility. When there is inflammation of the prostate, the citric acid content is significantly reduced.

4. Protein: Measured using the biuret method. The normal range is (36±0.8) g/dL. The proteins in semen mainly originate from the seminal vesicles and prostate gland, and can promote sperm motility and protect sperm from harmful environmental effects.

5. Trace elements: These play an important role in male reproduction and reproductive endocrine function. Normal semen contains (130±56) micrograms/mL of zinc, (185±0.15) micrograms/mL of copper, and (0.81±0.04) micrograms/mL of iron. Zinc in semen affects sperm metabolism and is directly proportional to sperm motility and density. It can also indirectly affect the gonads by influencing the pituitary gland. When zinc is insufficient, the secretion of pituitary gonadotropins decreases, leading to poor gonadal development or impaired reproductive and endocrine functions. Copper affects sperm survival rate and motility; high copper concentrations in semen result in poor sperm motility, and vice versa. Iron is significantly related to sperm density in semen; higher iron content in seminal plasma leads to higher sperm density, and vice versa.

Microbiological examination of semen

Microbiological examination of semen helps identify the pathogens causing inflammation and provides a basis for the rational use of antibiotics.

The method for collecting semen is the same as the conventional method. The collected semen is spread evenly on a glass slide, briefly fixed with a flame, and then subjected to Gram staining and acid-fast staining, followed by microscopic examination. Sometimes, general bacterial culture is also performed to observe colony growth. Based on the morphology and colony characteristics observed during staining and microscopic examination of the smear, biochemical tests are performed to identify the bacterial species. The main pathogenic bacteria in semen include Neisseria gonorrhoeae, Escherichia coli, Staphylococcus, Streptococcus, anaerobic bacteria, and Mycobacterium tuberculosis.

Bacteria associated with prostatitis include Staphylococcus, Streptococcus, anaerobic bacteria, Escherichia coli, and Corynebacterium diphtheriae. Pathogens associated with urethral infections include Neisseria gonorrhoeae, Escherichia coli, and Staphylococcus. Pathogens associated with epididymitis include Mycobacterium tuberculosis, Escherichia coli, Staphylococcus, and Streptococcus. Infections caused by these pathogens can affect semen liquefaction and lead to secondary azoospermia.

How to measure testicular volume

To understand testicular development, it is sometimes necessary to measure testicular volume. Currently, the commonly used measurement methods include:

1. Caliper measurement method: When measuring, use calipers to measure the length, width, and thickness of the testis, and then calculate the testis volume according to the formula: Testis volume (cm3) = length (cm) × width (cm) × thickness (cm) × π/6.

2. Testicle Comparison Method: Based on a pre-calculated volume, oval-shaped hard objects resembling testicles are made with different volumes, numbered 1 to 25 according to size. During measurement, the testicle to be measured is pulled up, the scrotal skin is tightened, and the testicle model (testicle) is compared one by one next to the testicle. The volume of the model that is similar in size to the testicle can be regarded as the testicle volume.

3. Displacement Measurement Method: During measurement, the testis to be measured is lowered, and warm water (around 25℃) is placed in a graduated container, ensuring the lowered testis is completely submerged. The increase in water volume in milliliters after immersion is taken as the testis volume. This method is now rarely used.

There is considerable individual variation in the volume of testicles in normal men, and there are also certain differences in the volume of the two testicles in the same individual. To determine the development status of the testicles and fertility, it is necessary to combine the results of other examinations and conduct a comprehensive analysis in order to draw a more scientific conclusion.

According to reports, the average testicular volume of adult men in my country is as follows: 19-23 years old: left testicle 13.1 cm ± 3.6 cm, right testicle 13.6 cm ± 4.2 cm; 24-45 years old: left testicle 13.6 cm ± 4.2 cm, right testicle 14.4 cm ± 4.5 cm (caliper measurement). The above data are for reference only.

Significance of testicular biopsy

Testicular biopsy is an important diagnostic method for male infertility. Through observation of the testes, the spermatogenic function and degree of spermatogenic impairment of the testes, as well as the testes' ability to synthesize steroid hormones, can be directly estimated, fertility can be assessed, and intuitive data can be provided. It is also an important basis for the selection of treatment and the judgment of prognosis.

Testicular biopsy can be performed in patients with unexplained azoospermia who have normal testicular volume and serum follicle-stimulating hormone (FSH) levels, or when testicular tumors are suspected. In patients with generalized Sertoli cell-only syndrome or seminiferous tubule hyalinization, the lesions are difficult to detect, and their serum FSH levels are elevated, so testicular biopsy is unnecessary.