Male Infertility is responsible for 20 - 30 % of all cases of infertility. The main cause of male infertility is a low or absent sperm count in the semen. Since only a single sperm is needed for a pregnancy, it is difficult to estimate a man's infertile status - while one man may be capable of fathering children with a sperm count of less than 10 million, another may not be able to do so even with a high sperm count.
But on the whole, a sperm count of less than 20 million is considered low. In a standard semen analysis, the sperm count is considered normal when it is above 40 million per ml of semen. Of these, at least 50% must show active forwards movement for a pregnancy to occur.
The normal volume of semen in one ejaculate should be 2ml. Less than 1.5 m is considered low volume (hypospermia) and more than 5.5ml is called hyperspermia.
The commonest causes of a low sperm count in Male Infertility are:
- Low production of sperm. Low production may cause a low sperm count or Oligospermia.
- Obstruction in the male genital tract. Obstruction will cause either oligospermia or azoospermia - which is complete absence of sperm in the semen.
Causes of low production of Sperm:
The causes of oligospermia is still not clear although a large number of theories have been put forward:
- Incomplete development of the testes: Sex chromosomal abnormalities that cause defective growth of the testes, e.g. aplastic testes are often associated with oligospermia.
- Non-descent or even late descent of the testes - In embryonic life, the testes is formed inside the abdominal cavity. They later descend to their normal position in the scrotum. In some men, the testes fail to descend totally or partially. The temperature of the abdominal cavity being 2 degrees above the scrotal temperature, the effect of the excess heat on the testes causes failure of development of sperms.
- Infections like mumps or other serious infections occurring after the age of 14 years can cause oligospermia. About 25 – 50% of all cases of adult mumps affect the testes.
- Varicocele: Varicocele is a condition where there is gross dilation of the veins surrounding the testes. This causes stagnation of blood which is believed to decrease sperm production by increasing the temperature in the testes or by releasing toxic material into the blood supply of the testes.
- Injury to the testes during accidents, surgeries and X-ray exposures may cause less sperm production and low sperm count.
- High and constant heat exposure prevent sperm formation - as for example frequent hot baths; wearing tight underwear which hold the testes firmly against the body, especially non-porous synthetic underwear; long distance driving where heat from the engine falls directly on the testes, etc.
- Diseases of the testes like tumours, syphilis, tuberculous.
- Diseases of other glands like the pituitary gland may cause decreased sperm production.
- Medicines and drugs like sulphonamides can affect spermatogenesis. Nicotine is a toxic chemical which can affect the testes and cause less sperm production. Deficiencies of Folic Acid, Zinc and Vit B12 are also believed to be responsible for low sperm count.
- Age Sperm production begins to fall after the age of 40 years, but this is not always responsible for infertility. Many men continue to father children till late in life.
- Antibodies and Spermagglutinins can cause low sperm count.
Obstruction of the Male Genital tract :
- Accident or operation of the genital tract, especially herniorrhaphy.
- Infections, commonly infections by the N. gonorrhoea organism.
- Absence of any part of the tract at birth, usually as a result of sex chromosomal defects.
- Faulty development of the tract.
Failure to Deposit Sperm in the Vagina
Failure to deposit sperm in the vagina is an uncommon cause of male infertility, but is sometimes known to occur.
- Impotance or failure of erection and penetration.
- Premature Ejaculation
- Defects in the penis like hypospadias and phimosis.
- Retrograde ejaculation into the bladder which can occur after operations like prostatectomy.
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