Oligospermia
semen with abnormally low concentration of sperm
Terms oligospermia, oligozoospermia, and low sperm count refer to semen with a low concentration of sperm and is a common finding in male infertility. Often, semen with a decreased sperm concentration may also show significant abnormalities in sperm morphology and motility (technically oligoasthenoteratozoospermia). There has been interest in replacing the descriptive terms used in semen analysis with more quantitative information.
Diagnosis
The diagnosis of oligozoospermia is based on one low count in a semen analysis performed on two occasions. For many decades sperm concentrations of less than 20 million sperm/ml were considered low or oligospermic, recently, however, the WHO reassessed sperm criteria and established a lower reference point, less than 15 million sperm/ml, consistent with the 5th percentile for fertile men. Sperm concentrations fluctuate daily, and oligozoospermia may be temporary or permanent.
The diagnosis of oligozoospermia requires a work-up via semen analysis (listed in Male infertility).
Causes
There are many causes for oligospermia, including:
Pre-testicular causes
Pre-testicular factors refer to conditions that impede adequate support of the testes and include situations of poor hormonal support and poor general health, including:
Hypogonadism due to various causes
Drugs, alcohol, smoking
Strenuous riding (bicycle riding, horseback riding)
Medications, including androgens.
Testicular factors
Testicular factors refer to conditions where the testes produce semen of poor quality despite adequate hormonal support and include:
Age
Genetic defects on the Y chromosome
Y chromosome microdeletions
Abnormal set of chromosomes
Klinefelter syndrome
Neoplasm, e.g. seminoma
Cryptorchidism
Varicocele (14% in one study)
Trauma
Hydrocele
Mumps
Malaria
Defects in USP26 enzyme in some cases
Mast cells releasing inflammatory mediators appear to directly suppress sperm motility in a potentially reversible manner, and may be a common pathophysiological mechanism for several of the factors mentioned above.
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