Male infertility is very common. About one in twenty men is sub-fertile and a male infertility factor may be significant in half of all infertile couples. About one third of all IVF procedures are performed for male factor infertility. For most men the discovery that they are infertile comes as a total surprise.

It must be remembered that the testes has two distinct roles. The first is to produce the male sex hormone, testosterone, which is important for the bodily changes of male puberty, providing sex drive, hair growth, strong muscles and basically giving a man a general feeling of well-being. All these things can be described as 'virility'. The second function of the testes is to produce millions of sperm everyday, a process that occurs inside the approximately 150 metres of fine tubes in each testes. For most infertile men it is only this process that is at fault and a reduced number or poor quality of sperm is produced.

Most infertile men produce low numbers of sperm that may also show both limited swimming ability (called motility) and are abnormally shaped. In such men, only a small number of normally shaped motile sperm are likely to swim up the women's fallopian tube into the vicinity of the egg, and even then may be unable to fertilise the egg.

Why does this problem develop?

We now believe that most cases are genetic. In other words, these men are born without the genetic information that would allow sperm production to occur normally. Sometimes there is a family history of sub-fertility but often the problem seems to arise spontaneously. At Monash University we have been researching this issue and find that small pieces of the Y (or so-called male), chromosome are missing in 5% of men with severe infertility. Presumably these missing pieces of genetic information are the cause for poor sperm production. Clearly we need much more research before we can point to particular genes in the majority of men. Without that knowledge, treatment for men to improve sperm counts is unlikely to become available.

In the remaining one third of infertile men, likely causes for infertility include:

• Obstruction to the passage of sperm from the back of the testes to the outside, resulting from blockage or absence of the sperm duct. Common causes include vasectomy, injury, other surgery or sexually transmitted disease.
• Production of antibodies to sperm following vasectomy or other trauma or infection. These antibodies are a common cause of infertility and prevent sperm swimming or sticking to the egg. Such antibodies can only be found using a special test on fresh sperm and is available only in a few laboratories including that at Monash IVF.
• Damage to the testes by a wide number of treatments, including chemotherapy or X-ray therapy.
• Erection or ejaculation difficulties due to a wide range of problems such as diabetes, MS, or previous prostate surgery. In these cases sperm can be found and used for IVF.
• Rarely, a deficiency in the brain pituitary hormones may result in low sperm counts. Its detection is important as it is readily treated with hormone injections.

In conclusion while the cause of infertility is uncertain in many men, certain conditions can be identified and treated. These facts make it essential that all infertile men have their situation thoroughly investigated.

Investigations of Male Infertility

Often the infertile man is entirely healthy but for some reason produces sperm of a quality that does not achieve a pregnancy. However some men have serious medical problems, such as a low male sex hormone, testosterone level. It is therefore very important that men in infertile relationships see a doctor trained in reproductive medicine. Previous fertility, genital surgery or infections, undescended testes and certain systemic diseases are of importance. The adequacy of sexual development, the size and texture of the testes and normality of the tubes attached to the back of the testes are assessed.

The most important test is the semen analysis that requires a great deal of expertise to comply with the high standards prescribed by the World Health Organisation. The laboratories of Monash Reproductive Pathology and Genetics are one of only a few in Australia meeting these criteria.

Semen quality varies widely between men. Even for a particular man, a minimum of two sperm counts at least four weeks apart need to be taken to give a true indication of his sperm quality. The test is performed after two to five days of sexual abstinence. Ideally the laboratory provides an appropriate collection room so avoiding changes in sperm temperature during the transport of samples to the laboratory.

A sperm count greater than 20 million/ml is considered normal, however the average for the population is about 80 million, and some men have a sperm count of above 200 million/ml. Sperm counts between five and 20 million do not necessarily indicate a severe infertility problem.

The ability of sperm to swim is termed motility. Normally, greater than 50% of sperm shows some forward motion. Markedly reduced motility can greatly reduce fertility.

The sperm shape, termed morphology, is an important predictor of fertility and the accurate assessment of this feature requires great skill.

Sperm antibodies are an important cause of infertility as they reduce the sperm's motility and ability to stick to the egg. They can be readily detected on fresh sperm at the time of semen analysis.

Blood hormone tests are also frequently performed. Poor testicular function can reduce testosterone levels that in turn impair sex drive and energy levels. The follicle stimulating hormone (FSH) test gives an indication of the amount of sperm being produced. In men with a blockage of sperm outflow, FSH levels are normal. However, when the testicle is severely damaged, and few or any sperm are being produced, FSH levels rise progressively.

A zero sperm count (termed azoospermia) may be due to either blockage in the tubes or to the failure of sperm production. A testicular biopsy, often using a fine needle under local anaesthesia, with microscopic examination, will readily clarify whether sperm are present in the testes. In some cases of blockage, further tests such as ultrasound of the prostate and bladder region are performed.

Finally, in men who produce little sperm and are considering using the single sperm microinjection procedure, there are two genetic tests which are frequently recommended to help understand why they have this problem, and to assess the risk of transmission to their future children. One involves counting the number of chromosomes, and the other looks for whether the man is missing part of the Y chromosome, that is important in controlling sperm production.

In conclusion, thorough clinical assessment of the man and the performance of a range of specialised hormone and sperm tests are needed to fully evaluate the infertile man.

Other Reading Matter

Additional information may be obtained from the Andrology Australia website www.andrologyaustralia.org