Factors relating to male infertility include:
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 those that affect spermatogenesis such as chemotherapy, anabolic steroids, cimetidine, spironolactone; those that decrease FSH levels such as phenytoin; those that decrease sperm motility such as sulfasalazine and nitrofurantoin
- Genetic abnormalities such as a Robertsonian translocation
Testicular factors
Testicular factors refer to conditions where the testes produce semen of low quantity and/or poor quality despite adequate hormonal support and include:
- Age
- See also: Paternal age effect
- Genetic defects on the Y chromosome
- Y chromosome microdeletions
- Abnormal set of chromosomes
- Klinefelter syndrome
- Neoplasm, e.g. seminoma
- Idiopathic failure
- Cryptorchidism
- Varicocele (14% in one study)
- Trauma
- Hydrocele
- Mumps
- Malaria
- Testicular cancer
- Defects in USP26 in some cases
- Acrosomal defects affecting egg penetration
- Idiopathic oligospermia - unexplained sperm deficiencies account for 30 % of male infertility.
Post-testicular causes
Post-testicular factors decrease male fertility due to conditions that affect the male genital system after testicular sperm production and include defects of the genital tract as well as problems in ejaculation:
- Vas deferens obstruction
- Lack of Vas deferens, often related to genetic markers for Cystic Fibrosis
- Infection, e.g. prostatitis
- Retrograde ejaculation
- Ejaculatory duct obstruction
- Hypospadias
- Impotence
