Infertility can be defined as the failure to achieve pregnancy after regular unprotected sex (without the use of any contraception) for at least a year.

• Primary infertility means failure to achieve a first pregnancy
• Secondary infertility means failure to achieve a subsequent pregnancy.

Primary infertility is an extremely common problem, affecting more than one in seven (15%) couples attempting their first pregnancy. Among those experiencing difficulty with conception, a male fertility problem is considered important in around 40% of couples. In 15% of couples it will be solely a male fertility problem and in around 25%, there will be a problem in both partners.

Fertility problems should not be confused with Erectile Dysfunction or Premature Ejaculation.

• Groin surgery (including hernia repair and fixation of undescended testicles).
• Trauma to the scrotum sack covering the testicles (even fairly minor sporting injuries).
• Infection (particularly chlamydia, gonorrhoea and tuberculosis).
• Previous vasectomy (a form of contraception that involves tying the sperm-carrying tubes).

Some men have congenital (present at birth) absence of the vas deferens on one or both sides. The vas deferens is the tube that conducts the testicular component of semen to the urethra, which then carries semen through the penis to the outside world.
About 10% of men with an obstructive cause for their infertility will have this problem. The seminal vesicles, (where other semen components are made) are often absent too.

Another rare obstructive cause is Berry-Perkins-Young syndrome, in which sufferers have a chronic chest disease (bronchiectasis), chronic sinusitis and obstructive infertility.

Testicular injury and disease: A blow to the testicles, which may occur in sport or during a fight or accident, can cause swelling of the testicles, or bleeding in or around them. This probably causes the blood supply to the testicles to fail, resulting in permanent damage to the sperm production mechanism. Torsion of the testicles (twisting of a testicle on its cord) can have a similar effect if it is not treated very quickly with surgery.

Viral infections can cause inflammation of the testicles (orchitis, which usually appears as painful swelling of the testicles) and failure of sperm production. Mumps is the best-known cause, but is not the only one. Mumps will only affect fertility if it causes orchitis and, even then, only rarely.

Undescended testicles (cryptorchidism) are another common cause of failure of sperm production. Male infants and children are routinely examined to identify this problem, as future fertility can only be preserved if surgical treatment to fix the testicles in the scrotum is performed in early childhood. Even surgery in infancy does not guarantee future fertility.

Varicocele: A varicocele is a dilation of the testicular veins in the spermatic cord that leads from the testicles to the abdomen. The role of this condition in causing infertility is uncertain and highly controversial. Varicoceles occur in 15-20% of fertile men and 30-40% of men with fertility problems. They can occur on either or both sides, but are far more common on the left. They are best identified when the man is standing up and are often described as feeling like "a bag of worms". Experts suggest that the varicocele either heats up the testicles or impairs their blood supply resulting in a build-up of body waste products, thus affecting fertility. The co-existence of other risk factors, such as smoking, with varicocele seems to have a greater effect on the risk of infertility.

Sperm disorders: Disorders of sperm numbers, movement and shape are common in men with infertility. Prolonged abstinence from ejaculation can affect sperm motility. Modern techniques can identify structural and biochemical abnormalities within the individual sperm.

Genetic disorders: Problems with chromosomes (packages of genetic material) occur in about 2-20% of infertile men and can affect their fertility in two ways:

• Chromosome disorders can affect the development of the testicles. These are usually disorders of the sex chromosomes, by far the most common being Klinefelter's syndrome. In this disorder, instead of having 46 chromosomes, including one X and one Y chromosome (46XY), the man has an additional X chromosome (47XXY).
• Chromosome abnormalities can disrupt cell division and sperm production.

• Impotence (inability to attain or maintain an erection adequate for intercourse)
• Premature ejaculation.
• Failure to ejaculate.
• Inability to achieve vaginal penetration for other reasons.

• Fever: Influenza, pneumonia, or even a severe cold can cause a high fever, which will adversely affect sperm production and quality. These changes usually recover over a few weeks.
• Diabetes: In the longer term, diabetes can cause problems with erection and ejaculation through causing damage to the function of the "automatic nervous system".
• High blood pressure: High blood pressure can cause problems with erection, either directly or as a side effect of medication e.g. amlodipine.
• Coronary artery disease: Coronary artery disease can cause problems with erection. This could be due to generalised hardening of the arteries, in the penis as well as the heart, or to drugs used in the treatment of heart problems.
• Neurological disorders: Multiple sclerosis, stroke, and spinal cord injury and disease can all cause problems with erection and ejaculation.
• Kidney disease: Chronic renal failure, which results in a build up of waste products in the body, can adversely affect sperm quality and fertility. It can also cause erection problems.
• Cancer: Cancers that affect the genital tract or endocrine (hormone-producing) systems may directly reduce fertility. Otherwise, drugs and radiation used to treat cancer may severely reduce sperm production or even stop it altogether. Stress (see below) may also have an effect.
• Alcoholism: Alcohol is toxic to sperm and overuse of alcohol can reduce sperm quality and fertility.
• Stress: Stress causes several hormonal changes in the body that can affect fertility. Stress can have many causes, including anxiety over fertility problems.

There are a number of things that men can do to help preserve and promote their fertility:

• Eating a healthy, balanced diet.
• Taking regular exercise.
• Trying to maintain their weight in the ideal range.
• Not smoking.
• Keeping alcohol consumption within recommended limits
• Not use recreational drugs.
• Reducing stress.

Several other actions have been suggested. Some may improve sperm quality parameters, but evidence that they improve the successful pregnancy rate is poor or non-existent:

• Avoiding tight underwear - the evidence for benefit from this is very poor.
• Cold showers or scrotal soaks - while these might take the mind off fertility concerns for a few moments, there is no evidence of their effectiveness.

Diagnostic testing for male factor infertility often includes:

• a complete history and physical examination
• multiple semen analysis - at least two semen examples are collected on separate days to examine the semen and sperm for various factors, such as semen volume, consistency, and pH, and the sperm count, motility, and morphology (shape).
• other tests - to determine sperm abnormalities or diseases of the male reproductive system.

1..Assisted ReproductiveTechnologies (ART) - this type of treatment may include:

• Artificial insemination - this involves the placement of relatively large numbers of healthy sperm either at the entrance of the cervix or into the partner's uterus, bypassing the cervix, to have direct access to the fallopian tubes.
• IVF, GIFT and other techniques such as in vitro fertilization (IVF) or gamete intra-fallopian transfer (GIFT) have been used for the treatment of male infertility. As is the case with artificial insemination, IVF and similar techniques offer the opportunity to prepare sperm in vitro, so that oocytes are exposed to an optimal concentration of high quality, motile sperm.
• Microsurgical fertilization (microinjection techniques) - this is used to facilitate sperm penetration into the oocyte, and fertilization takes place under the microscope.

2. Drug therapy - a small percentage of infertile men have a hormonal disorder that can be treated with hormone therapy. Hormonal imbalances caused by a dysfunction in the mechanism of interaction between the hypothalamus, the pituitary gland, and the testes directly affect the development of sperm (spermatogenesis). Drug therapy may include gonadotrophin therapy, antibiotics, or another drug deemed appropriate.

3. Surgery - surgical therapy in male infertility is designed to overcome anatomical barriers that impede sperm production and maturation or ejaculation. Surgical procedures to remove varicose veins in the scrotum (varicocele) can sometimes serve to improve the quality of sperm.