Azoospermia is defined as the absence of sperm in the ejaculated semen (WHO 1999). Clinically, the diagnosis is usually confirmed after 3 centrifugal microscopic examinations of the semen with no spermatozoa still visible and should exclude conditions such as non-ejaculation and retrograde ejaculation. The incidence of azoospermia is 5%-20% in the population of infertile men, while in the general population it is about 2%. Azoospermia is defined as the absence of sperm on three consecutive centrifugal microscopic examinations of semen and the exclusion of ejaculation and retrograde ejaculation before the diagnosis is confirmed. Azoospermia is an extreme case of male infertility, and its incidence accounts for 8% to 10% of infertile men. Azoospermia can be divided into two main categories. The first category is testicular spermatogenic dysfunction, where sperm cannot be produced, also known as true azoospermia. The second category is normal testicular spermatogenesis, but the vas deferens is blocked and sperm cannot be discharged from the body, also known as obstructive azoospermia. Causes There are many causes of azoospermia, but they are summarized in two main categories: 1. Testicular azoospermia: azoospermia caused by various causes of testicular sperm production dysfunction, such as Crohn’s syndrome, bilateral cryptorchidism, long-term consumption of crude cottonseed oil, mumps orchitis, varicose veins of the spermatic cord, radiation damage, endocrine disorders, etc. 2, obstructive azoospermia: obstructive azoospermia is caused by obstruction or absence of the vas deferens due to various reasons, so that the sperm produced by the testes cannot be discharged through the vas deferens and cause azoospermia, the most common causes are male vasectomy, congenital absence of the vas deferens gland or obstruction of the vas deferens adhesion due to inflammation, such as epididymitis or epididymal tuberculosis, etc. Symptoms of azoospermia The diagnosis of azoospermia can be confirmed if no sperm is found in the semen after centrifugation and microscopic examination of the sediment for 3 times, but further clarification of the cause is needed. During physical examination, attention should be paid to the development of secondary sexual characteristics and external genitalia development. If the testicular volume is less than 10 ml and the texture is abnormally soft, it often indicates poor testicular function, and palpation should pay attention to the epididymis and vas deformities and nodules. [1] Endocrine examination, serum FSH (follicle stimulating hormone), LH (luteinizing hormone), PRL (prolactin), T (testosterone), and DHT (dihydrotestosterone) can help to identify whether primary or secondary testicular failure is present. Testicular ultrasound can detect gross testicular lesions, and testicular biopsy can provide a more definitive basis for diagnosis and treatment. There are two types of azoospermia: true azoospermia is due to atrophy and degeneration of testicular spermatogenic cells, which cannot produce sperm, also known as “congenital azoospermia”; false azoospermia is when the testicles can produce sperm, but due to the blockage of the vas deferens, sperm cannot be discharged, so it is also known as obstructive azoospermia. Azoospermia is clinically uncommon, but they basically or completely lose their fertility. Through a combination of Chinese and Western medicine treatment, there are also those who succeed and become pregnant, but most of them are irreversible, so they belong to the category of absolute infertility. The absence of sperm in the semen and the inability to make the woman pregnant are the fundamental diseases of male infertility. The Chinese medical literature is called “childlessness” and “infertility”. This is mostly a deficiency of both kidney yin and yang. It is mostly caused by congenital deficiency or acquired testicular injury: cryptorchidism, etc. There is also obstruction to the transmission of the stasis, which is a real evidence. What are the examination methods for azoospermia? The sperm is produced by the testes, and the varicocele in the testes contains a large number of spermatogenic epithelial cells, which mature into sperm through mitosis. Once azoospermia is diagnosed, further tests should be done to determine the exact cause of the azoospermia. Some of the more common tests are testicular biopsy, which involves removing a small amount of varicocele tissue from the testicle for pathological examination to determine the sperm-producing function of the testicle. Another is vasovasography, which is suitable for patients with normal testicular sperm production function after testicular biopsy and no sperm in the semen, and it can clearly diagnose whether the vas deferens is open and the site of obstruction. Another one is the quantitative determination of endocrine hormone release. This method can clarify the specific cause of azoospermia caused by pituitary or hypothalamic or testicular or endocrine dysfunction, which plays a vital role in guiding the treatment of azoospermia. In conclusion, only when the cause is clearly identified can treatment be purposeful and have the desired therapeutic effect. Notes on the examination of obstructive azoospermia 1. Patients with general inflammatory obstruction are accompanied by a history of infection of the reproductive tract, such as orchitis and epididymitis, and for patients with a history of tuberculosis, the possibility of causing obstructive azoospermia is greater. 2. Semen examination is performed at least 2 times with an interval of 2 to 3 months, and semen is centrifuged according to WHO standards. Those with semen volume less than 1.5 ml, acidic pH and fructose negative are first considered to have obstructive azoospermia. When the semen volume is low, post-ejaculatory urine examination should also be done to discharge retrograde ejaculation. 3. Scrotal ultrasound is helpful for the detection of some obstructive signs, such as epididymal cysts, vas deferens, etc., and can also discharge testicular dysplasia. Transrectal ultrasound can also detect whether the seminal vesicles are absent, ejaculatory duct obstruction and dilated ejaculatory ducts. 4. The testicular volume of patients with obstructive azoospermia is usually within the normal range. For patients with epididymal obstruction and vas deferens obstruction, it is usually possible to palpate epididymal or vas deferens nodules, or vas deferens agenesis or partial atresia. Why is a testicular biopsy performed in patients with azoospermia? A testicular biopsy is a routine test for azoospermia. It takes only a few seconds to perform a small procedure on the testicles to get a complete picture of spermatogenic function. It plays a definitive role in guiding the next step of treatment. Testicular biopsy is performed by staining pathological sections of testicular varicocele tissue and determining the testicular spermatogenic function of that patient by direct observation of the spermatogenic function of the varicocele through a microscope. It is an important tool in the diagnosis of male azoospermia. In the past, a small amount of testicular tissue was extracted or excised using the puncture or incision method, and pathological sections were stained for microscopic observation. The puncture and aspiration method often requires multiple puncture and aspiration, and has considerable false positives and false negatives, because needle aspiration cytology examination can only obtain a few tissue cells and cannot see the overall structure of the tissue, which is of little significance for the diagnosis of azoospermia.