Male infertility symptoms are the result of many diseases or factors, usually divided into pre-testicular, testicular and post-testicular segments according to the different diseases and factors that interfere with or affect the birth needle segment, but there are still up to 60-75% of patients who cannot find the cause (clinically known as idiopathic male infertility).
I. Pre-testicular factors
Pre-testicular factors: endocrine causes of male infertility, the impairment of reproductive function in these patients is secondary to the imbalance of hormones in the body.
1. Thalamic diseases
1.1 Gonadotropin deficiency
Kallmann’s syndrome is a syndrome of hypogonadotropic hypogonadism, which was reported by Kallmann in 1944. The lesion is located in the hypothalamus and is secondary to hypogonadotropic hypogonadism due to impaired secretion of hypothalamic gonadotropin-releasing hormone (GnRh), resulting in decreased gonadotropin secretion.
1.2 Selective LH deficiency
This disease, also known as reproductive azoospermia, is rare and clinically manifests as azoospermia-like signs of varying degrees of androgenesis and male-breast feminization. The patient has normal or slightly large testes, low semen volume, and occasionally a few spermatozoa. Microscopically, mature spermatogenic epithelium is visible, but interstitial cells are rare.
1.3 Selective FSH deficiency
The disease is extremely rare, with insufficient pituitary FSH secretion and normal LH. The patient clinically presents with normal male sexual characteristics and testicular volume, azoospermia or extreme oligospermia.
1.4 Congenital hypogonadotropic syndrome
Hypogonadism secondary to several syndromes, such as Prader-Willi syndrome and Laurence-Moon-Bardet-Biedl syndrome.
2. Pituitary disorders
2.1 Pituitary insufficiency
Due to tumor, infection, infarction, surgery, radiation, infiltration and granulomatous lesions affecting pituitary function. Laboratory tests suggest: low blood testosterone level with low or normal low gonadotropin, serum corticosteroids will decrease in those with total pituitary dysfunction, and blood FSH and growth hormone levels will decrease.
2.2 Hyperprolactinemia
Primary hyperprolactinemia is commonly seen in pituitary adenomas. Hyperprolactin causes a decrease in FSH, LH and testosterone, leading to loss of libido, ED, breast overflow, male breast enlargement and spermatogenic disorders, sometimes accompanied by other hormone metabolism disorders.
3. Endogenous or exogenous hormone abnormalities
3.1 Excessive estrogen and/or androgen
Exogenous androgen increase is common in oral steroid hormone, congenital adrenal hyperplasia, adrenal tumor with hormonal activity or testicular interstitial cell tumor. Excessive obesity and liver insufficiency are common causes of estrogen increase, and they are also related to some tumors that can secrete estrogen such as adrenal cortical tumors, testicular support cell (Sertolicell) tumors or mesenchymal stromal cell tumors.
3.2 Excessive glucocorticoids
Excessive glucocorticoids can inhibit LH secretion, leading to impaired spermatogenesis and maturation. This is mostly seen in Cushing’s syndrome or increased intake of medical origin.
3.3 Hyper- or hypothyroidism
The balance of thyroid function affects spermatogenesis through both the pituitary and testicular levels. hyperthyroidism or hypothyroidism can alter hypothalamic hormone secretion and the estrogen/androgen ratio. abnormal thyroid function accounts for about 0.5% of male infertility causes.
Second, testicular factors
1, congenital abnormalities
1.1 Chromosomal or genetic abnormalities
About 6% of infertile men have genetic material abnormalities, and the proportion gradually increases as the sperm count decreases. 1% of those with normal sperm count, 4% to 5% in oligospermia, and the highest proportion reaches 10% to 15% in azoospermia.
1.1.1 Creutzfeldt-Jakob syndrome. The genetics of Creutzfeldt-Jakob syndrome is characterized by sex chromosome aneuploidy abnormalities, 90% are 47, xxy, and 10% are 47 chimeric.
1.1.2 XX male syndrome (also known as sexual inversion syndrome). The disease is due to the translocation of the testicular determinant region gene (SRY) on the Y chromosome to the X chromosome during meiosis, but the gene controlling spermatogenesis (AZF) remains on the Y chromosome, thus leading to azoospermia.
1.1.3 XYY syndrome (XYY syndrome). The disease is the result of the failure to separate the Y chromosome during the second meiotic division in which the father’s spermatozoa are formed.
1.1.4 Noonan syndrome (Noonansyndrome). Also known as Turner syndrome in men, most of the karyotypes are normal 46, XY, and a few are (X/XY) chimeric.
1.1.5 Y chromosome microdeletion. About 15% of patients with azoospermia or severe oligospermia have Y chromosome microdeletions, which can be detected by PCR analysis. The common microdeletions are AZFa, AZFb, AZFc, and recently the AZFd region has been delineated on the proximal side of AZFc, and the DAZ gene, which regulates germ cell meiosis, is located in the AZFc region.
1.2 Cryptorchidism. Cryptorchidism is an extremely common congenital malformation of the genitourinary system in children. The prevalence of cryptorchidism is about 30% in premature infants, 3.4%~5.8% in newborns, 0.66% at the age of 1 year, and 0.3% in adults.
1.3 Androgen dysfunction. The former is mainly due to an abnormality in one part of the androgen signaling process, while the latter includes mainly: 5α-reductase deficiency and androgen receptor abnormalities.
1.4 Other less common syndromes: myotonic dystrophy, orchidrosis, and supportive cell only syndrome, etc.
2.Germinal gland toxins
3.Systemic diseases
Systemic diseases leading to infertility are often the result of a combination of multiple factors. Systemic diseases that often cause infertility include renal failure uremia, liver cirrhosis hepatic insufficiency, sickle cell disease, etc.
4, infection (orchitis)
Mumps after puberty 30% combined with orchitis, often unilateral, bilateral incidence of 10% to 30%, testicular atrophy is the most common serious consequences of viral orchitis, but it is less common in bacterial infections.
5. Testicular trauma and surgery
Testicular location superficial, easy to be injured, in addition to lead to testicular atrophy, but also can stimulate abnormal immune response, both can lead to infertility; testicular blood vessels, vas deferens of medical injury can also lead to infertility.
6, vascular factors.
Varicocele, testicular torsion rate of 15%, 90% is located on the left side, the incidence of nearly 40% in infertility patients. Varicocele causes infertility as a result of a combination of factors, although varicocele as a cause of infertility has been controversial and no conclusive evidence of the disease affecting fertility has been found to date.
Testicular torsion can cause ischemic damage to the testis, and the degree of damage is related to the degree and duration of ischemia, and it is now believed that torsion on one side can cause histological changes in the opposite testis.
7. Immunological factors.
Male infertility caused by positive anti-sperm antibodies.
Third, post-testicular factors
1, vas deferens obstruction
Vas deferens obstruction is one of the important causes of male infertility, and obstructive azoospermia is about 7% to 10% in male infertility patients.
1.1 Congenital obstruction. Obstruction can occur at any part of the vas deferens, from the testicular network . epididymis . vas deferens up to the opening of the ejaculatory duct.
1.1.1 Cystic fibrosis (Cysticfibrosis): an autosomal recessive disorder, almost all male patients with cystic fibrosis have congenital absence of the vas deferens (CBAVD).
1.1.2 Young’s syndrome: the main manifestation of the triad: chronic sinusitis . Bronchiectasis and obstructive azoospermia. Normal spermatogenic function, but manifests as azoospermia due to obstruction of the epididymis by concentrated material. The success rate of surgical reconstruction is low.
1.1.3 Idiopathic epididymal obstruction: the disease is rare. 1/3 patients have cystic fibrosis gene mutation, which may be related to cystic fibrosis.
1.1.4 Adult polycystic kidney disease (APKD): It is an autosomal dominant disorder in which patients have multiple cysts in their internal organs, which can lead to infertility when there are obstructive cysts in the epididymis or seminal vesicle glands.
1.1.5 Ejaculatory duct obstruction: accounts for 5% of the causes of azoospermia and can be congenital such as Mullerian duct swelling. Wolf’s duct cyst or atresia, but also acquired such as seminal vesicle stones or scars from surgical inflammation.
1.2 Acquired obstruction. Mainly reproductive system infections . Vasectomy . Accidental surgical injury to the vas deferens in the inguinal region and inflammatory reaction around the vas deferens after the application of a patch in hernia repair resulting in vas deferens obstruction.
1.3 Functional obstruction. Any factor that interferes with nerve conduction in the vas deferens and bladder neck can lead to non-ejaculation or retrograde ejaculation, with common causes such as nerve injury and drugs
2. Sperm function or motility disorders
2.1 Cilia immobility syndrome. This disorder is caused by the reduction or loss of motility of sperm due to abnormalities in their motile apparatus or axons, which leads to fertility disorders.
2.2 Maturation disorders. It is commonly seen after vasectomy recanalization. As the long-term high pressure in the epididymal duct after ligation damages the function of the epididymis, the spermatozoa do not acquire normal maturation and motility when passing through the epididymis after recanalization, so the vitality is low, but the number of spermatozoa can be normal.
3.Immune infertility
Anti-sperm antibodies (AsAb) are an important cause of immune infertility. Common causes include testicular trauma, torsion, biopsy, infection or vas deferens plugging, after anastomosis surgery, etc.
4.Infection
According to the service, 8% to 35% of infertility is related to infectious inflammation of the male reproductive tract, mainly infection leading to obstruction of the vas deferens, anti-seminal antibody formation, bacteriospermia, the role of leukocytes in semen, and abnormal seminal plasma.
5, sexual intercourse or ejaculatory dysfunction
Hypoactive sexual desire, ED, ejaculatory dysfunction is a common cause of infertility, in addition to some organic causes, most of which can be cured through sexual counseling; anatomical abnormalities such as hypospadias can lead to infertility due to ejaculation of semen too far from the cervix; diabetes, inflammation of the bladder urethra, abnormal bladder neck muscles, hypospadias, surgery or traumatic injury to the nerves can also lead to non-ejaculation or retrograde ejaculation; bad sexual habits such as sexual intercourse too frequent, application of stimulants, lubricants, etc. can also affect fertility.
IV. Idiopathic causes
Idiopathic infertility in men refers to male infertility can not find the exact cause, its interference or impact on reproductive links may involve the testes before, testes, testes after one or several links. With advances in science and technology, hereditary or environmental factors may be able to uncover most causes.