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Causes of infertility

Details male infertility and causes of male infertility.

What is male infertility?

Male infertility is defined as the inability of a man to father a child despite regular unprotected intercourse. It affects one in 20 men. Furthermore, the male partner has suboptimal sperm parameters in nearly half of infertile couples. Most subfertile men defer having consultations because they perceive subfertility as a threat to their musculinity. Although male infertility may be associated with impotence, many infertile men have perfectly normal and happy sexual relationships.

Male infertility can be classified into four main types:

  • No sperm (azoospermia) accounts for 3-4% of male infertility.
  • Poor sperm quantity (oligospermia) or quality such as low motility (asthenozoospermia), or a high percentage of abnormal sperm (teratozoospermia) or multiple sperm defects termed oligoasthenoteratozoospermia (OATS). Antisperm antibodies, etc. This subgroup may account for about 90% of male infertility.
  • Sperm dysfunctional, where there is a normal semen analysis but the sperm lack or have a defective fertilizing capacity, resulting in complete failure of fertilization or poor fertilization of the eggs in IVF. This accounts for 3-6% of male infertility.
  • Inability to ejaculate into the vagina. This accounts for 4-6% of male infertility.

In the majority of men suffering male infertility, physical and genital examinations reveal no cause of infertility, but in a few cases, it may reveal abnormalities such as poor facial and bodily hair, enlarged breasts, undescended testis, small testes or varicocele.




Male infertility due to no sperm in the ejaculate.

Possible causes include either failure of the testicles to make sperm, or the testicles are making sperm but because the vas deference are either blocked or congenitally did not develop, no sperm is seen in the ejaculate. Infection such as tuberculosis, sexually transmitted diseases duch as Gonorrhoea and Chlamydia may cause obstruction of the vas. In the majority of men in whom the testicles are not making sperm, there is no apparent reason. However, in a few there is history of trauma to the testicles, torsion of the testicles, undescended testis, severe mumps infection after puberty, or the pituitary gland is not producing enough gonadotrophic hormones. Chemotherapy or radiotherapy for cancer might have damaged the testicles.

Genetic defects e.g. chromosomal abnormality such as Klinefelter's syndrome, and Y chromosome micro deletions (a tiny abnormality in the area of a Y chromosome which affects fertility) may also lead to no sperm in the ejaculate. Kallman syndrome (Hypothalamus failure to produce gonadotrophin releasing hormone).

Some cases of congenital bilateral absent of vas (the tube that carries the sperm) are associated with cystic fibrosis. In some infertile men, the absence of sperm in their ejaculate is due to retro-grade ejaculation (during orgasm, sperm enter the bladder and mix with urine, rather than are ejaculated into the vagina). This is a rare condition and accounts for less than 1% of male infertility, retrograde ejaculation may follow surgeries such as the removal of prostate and can be a side effect of certain drugs etc. As the sperm are normal, they may be recovered from the urine and used for insemination or IVF.

Male infertility due to poor sperm quantity or quality

This could be due to many factors such as hormone deficiency, varicocele (abnormal swollen blood vessels around the testicles Among adult males with varicoceles, 90% are present unilaterally on the left side while 10% are present bilaterally. Not all varicoceles are related to male infertility, and men with high grade varicoceles can still father children. Varicoceles affect up to 50% of male with primary subfertility and up to 80% of men with secondary subfertility.Varicocele is associated with a decrease in sperm count, sperm motility and morphology and sperm DNA fragmentation), other causes include infection, drugs such as antidepressants, antihypertensive drugs (taken for high blood pressure), anabolic steroids used for body building and social drugs such as marijuana and cocaine, heavy smoking and excess alcohol, obesity and contact with some pesticides. Other causes include frequent hot baths and saunas. Testicular cancer is also associated with an increased risk of impaired sperm production (it occurs in middle age men, whereby the risk is increased in men who have had a history of undescended testicles). Furthermore, antibodies to sperm (antisperm antibodies) adversely affect sperm production.No identifiable cause in 25% of patients (Sharp et al, 2002)

Male infertility due to impaired sperm fertilizing capacity

This could be due to defective acrosomes, abnormal lateral head movements of sperm, inability of sperm to bind to the zona pellucida, or excess free oxygen radicals in the semen or sperm DNA fragmentation.

Male infertility due to the inability to ejaculate into the vagina

This could be due to reduced libido, failure of erection (impotency), premature ejaculation, or the inability to ejaculate etc.

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