Azoospermia is the absence of spermatozoa in ejaculated semen after centrifugal sedimentation and microscopic observation for three consecutive times. It accounts for 10%-20% of male infertility, and is currently a major diagnostic and treatment problem in male infertility. Azoospermia is divided into obstructive azoospermia and non-obstructive azoospermia.
1, pre-testicular factors
(1) Idiopathic hypogonadotropic hypogonadism (IHH) and Kallamann syndrome
Clinical manifestations of azoospermia and oligospermia are possible. Kallamann’s syndrome is characterized by loss of smell or hyposmia in addition to IHH symptoms.
(2) Hyperprolactinemia (PRL)
Pituitary adenomas are the most common cause of hyper-PRLemia. High PRL inhibits gonadotropin secretion and causes hypogonadism.
(3) Selective follicle stimulating hormone (FSH) deficiency
FSH deficiency causes reduced spermatogenesis, but LH activity and androgen levels are normal.
2.Testicular factors
(1) Primary testicular insufficiency
a. Klinefelter syndrome
The clinical manifestations of Klinefelter syndrome are small, hard testes, gynecomastia, azoospermia and hypogonadism, and degeneration of the vas deferens. The karyotype is 47, XXY. Hormonal manifestations in patients with Crohn’s syndrome are markedly reduced testosterone, which remains low into adulthood, and very low levels of serum inhibin B, accompanied by elevated FSH levels.
b. Support cell only syndrome
Clinical manifestations are.
(1) Normal male development ;
(2) Semen testing for oligospermia or azoospermia;
(3) Small testicular volume or less than the lower limit of normal, with normal or slightly hard texture;
(4) Elevated FSH, normal LH and T.
c. Cryptorchidism
Cryptorchidism is one of the most common causes of azoospermia. 85% of patients with bilateral cryptorchidism can develop azoospermia if left untreated, and even after surgical treatment, 46% of patients still develop azoospermia. With or without treatment, 13% of patients with unilateral cryptorchidism can develop azoospermia.
d.Urethral hypospadias
e. Anencephaly
This includes congenital azoospermia and acquired azoospermia, where genetic diseases, intrauterine infections, trauma, and teratogenic factors cause bilateral or unilateral testicular agenesis. Acquired anorchidism includes causes such as trauma, tumor, severe infection, and surgical accident.
f. Y chromosome microdeletion
According to statistics, the incidence of chromosomal abnormalities in male infertility patients is 2% -5%, and in azoospermia it is as high as 15%, chromosomal abnormalities are gradually being recognized as an important cause of male infertility .
(2) Secondary testicular insufficiency
a. Mumps
Some children have suffered from mumps, and 40% of post-pubertal mumps combined with post-mumps testicular epididymitis can seriously affect spermatogenesis and sperm maturation.
b. Lead poisoning
Domestic and foreign studies have shown that the incidence of libido loss, erectile and ejaculatory disorders are higher in men who work with lead, and lead has certain toxic effects on spermatogenic tubules and spermatogenesis. Lead work male sperm count, sperm viability decline, and lead to sperm malformation.
3, post-testicular factors
(1) obstruction of the vas deferens
Acquired factors leading to vas deferens obstruction include.
(1) Reproductive tract infection: severe reproductive tract infection can lead to obstructive azoospermia, with pathogenic bacteria such as gonococcus and mycobacterium tuberculosis being the most common.
(2) Trauma: trauma and surgery causing injury to the scrotum, perineum, urethra, etc. Vasectomy can also cause azoospermia. Some inappropriate diagnostic and treatment operations may lead to medically induced injuries, such as hernia repair, cryptorchidism and other surgical injuries, misligation, etc. Spermography can also lead to obstruction.
(3) Tumor: caused by tumor invasion or compression of vas deferens and ejaculatory duct.
(2) Varicocele
It is one of the most important factors causing male infertility and can lead to oligozoospermia and azoospermia. Its occurrence is related to mechanisms such as cadmium toxicity, oxidative damage, androgen deficiency, and elevated testicular temperature. Depressed blood from dilated veins in the scrotum leads to local hypoxia, increased temperature in the scrotum and increased hydrostatic pressure in the testes, as well as the effect of harmful substances such as adrenal metabolites such as 5hydroxytryptamine in the regurgitated blood, which eventually leads to testicular spermatogenesis disorders and decreased androgen production. One third of the adolescent boys with degree II and more than half of the adolescent boys with degree III VAC had decreased testicular volume on the affected side. 80% of these boys had a significant increase in testicular volume after surgical correction, with a mean follow-up of 3.3 years and 25% testicular enlargement.
(3) Bilateral vas deferens
Congenital bilateral vas deferens accounts for 1% to 2% of male infertility and 10% to 20% of obstructive azoospermia. Patients with congenital absence of vas deferens, normal testicular texture and volume, and normal spermatozoa occurrence, have no spermatozoa in semen examination because bilateral vas deferens prevents spermatozoa from running, but no abnormalities in karyotype and reproductive hormone levels are seen.
4. Other factors
There is evidence that smoking can impair sperm quality, and cotton phenol, a polyphenolic compound derived from human cotton seeds, has a male contraceptive effect and can cause azoospermia. Chemicals that cause male infertility include: bisphenol A, an important raw material for polymer synthesis materials (such as epoxy resins, polycarbonate plastics), which affects male spermatogenesis; octylphenol, a chemical widely used in the manufacture of detergents, cosmetics and oil paints and other products, can lead to apoptosis of testicular germ cells; styrene, dibutyl phthalate and methanol can cause serious effects on the male reproductive system, which It can lead to azoospermia; anti-cancer drugs such as cisplatin can also lead to a decrease in sperm count and viability.