Azoospermia
Azoospermia is the medical condition in which a man's semen contains no sperm. It is linked to male infertility, but many types can be treated medically. In humans, azoospermia affects about 1% of the male population and may be seen in up to 20% of male infertility cases in Canada.
In a non-pathological context, azoospermia is also the desired result of a vasectomy.
Classification
Azoospermia can be classified into three major types as listed.[3] Many of the conditions mentioned may also lead to various degrees of oligospermia instead of azoospermia. Pretesticular and testicular azoospermia are referred to as non-obstructive azoospermia, while post-testicular azoospermia is considered obstructive.
Pretesticular
Pretesticular azoospermia is characterized by insufficient stimulation of otherwise normal testicles and the genital tract. Typically, levels of follicle-stimulating hormone (FSH) are low (hypogonadotropic), consistent with the inadequate stimulation of the testes to produce sperm. Examples include hypopituitarism (due to various causes), hyperprolactinemia, and exogenous FSH suppression by testosterone. Chemotherapy can also suppress spermatogenesis. Pretesticular azoospermia affects approximately 2% of cases of azoospermia. It is a type of non-obstructive azoospermia.
Testicular
Testicular azoospermia refers to the testes being abnormal, atrophic, or absent, resulting in severely disrupted to absent sperm production. FSH levels are typically elevated (hypergonadotropic) due to an interrupted feedback loop, specifically a lack of feedback inhibition on FSH. This condition is present in 49–93% of men with azoospermia. Testicular failure encompasses both the absence of sperm production and a low level of production with maturation arrest during spermatogenesis.
Causes of testicular failure can be congenital, seen in certain genetic conditions (e.g., Klinefelter syndrome), some instances of cryptorchidism, or Sertoli cell-only syndrome. They may also be acquired through infections (orchitis), surgical interventions (trauma, cancer), radiation exposure, or other factors. Mast cells that release inflammatory mediators seem to directly inhibit sperm motility in a potentially reversible way and may represent a common pathophysiological mechanism for various inflammatory causes. Testicular azoospermia is classified as a type of non-obstructive azoospermia.
In general, men with unexplained hypergonadotropic azoospermia should undergo a chromosomal evaluation.
Post-testicular
In post-testicular azoospermia, sperm are produced but not ejaculated, a condition that affects 7–51% of azoospermic men. The primary cause is a physical obstruction (obstructive azoospermia) of the post-testicular genital tracts. The most common reason for this is a vasectomy performed to achieve contraceptive sterility. Other obstructions can be congenital, such as agenesis of the vas deferens observed in certain cases of cystic fibrosis, or acquired, like ejaculatory duct obstruction due to infection.
Ejaculatory disorders encompass retrograde ejaculation and anejaculation; in these conditions, sperm are produced but not expelled.
Unknown
Idiopathic azoospermia refers to the absence of a known cause for the condition. It may result from various risk factors, including age and weight. For instance, a 2013 review found that oligospermia and azoospermia are significantly linked to being overweight (odds ratio 1.1), obese (odds ratio 1.3), and morbidly obese (odds ratio 2.0), though the underlying cause remains unclear. The review also found no significant relationship between oligospermia and being underweight.
- More information is available at [ Wikipedia:Azoospermia ]
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