Male Infertility – What Causes Male Infertility?

Male Infertility - What Causes Male Infertility?

Male infertility is very common. About one in twenty men is sub-fertile and a male factor is present 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.

The Roles Of The Testis

It must be remembered that the testis has two distinct roles. The first is to produce the male sex hormone, testosterone, which is important for providing sex drive, erections, 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 testis is to produce millions of sperm everyday, a process which occurs inside the approximately 150 metres of fine tubes in each testis. For most infertile men it is only this process which is at fault and as a result, a reduced number or poor quality of sperm are produced.

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

Why Does Low Sperm Count Develop?

We now believe that most cases are genetic. In other words, these men are born without the genetic information which would allow sperm production to occur normally. Monash University have been researching this issue and find that small pieces of the Y, or so called male chromosome, missing in men with severe infertility. Presumably these missing pieces of genetic information are the cause for the poor sperm production. But we need much more research before we can point to particular genes. Without that knowledge no treatment for men to improve sperm counts is likely to become available. IVF techniques offer hope now as they require very much fewer normal sperm than does nature.

In the remaining one third of infertile men, we can find a likely cause for their infertility, including an obstruction to the passage of sperm from the back of the testis to the outside, which can result from blockage or absence of the vas deferens. Other common causes include, obviously, vasectomy, but any history of injury, and other surgery or sexually transmitted disease may be important.

Men can make antibodies to their 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 Monash IVF.

The testis can be damaged by a wide number of treatments including chemotherapy or X-Ray therapy.

Some men have difficulties obtaining an erection, or in ejaculating 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.

Is It True That There Has Been A Worldwide Decline In Sperm Count?

There remains great controversy as to whether sperm counts have declined worldwide. The alleged change is quite small (about 15%) and no cause has been confidently identified.

While the causes of infertility are 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 poor quality sperm. However some men have serious medical problems such as a low male sex hormone level (testosterone). 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 which requires a great deal of expertise to comply with the high standards prescribed by the World Health Organisation. The laboratories of Monash IVF in Melbourne and Queensland are two of only a few meeting these criteria.

Semen quality varies widely between men. Even for a particular man a minimum of two sperm counts at least three 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 temperature during the transport of samples to the laboratory.

What Is A Normal Sperm Count?

A sperm count greater than 20 million/ml is considered normal, however the average for the population is about 60 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 fifty per cent of sperm show some motility. Markedly reduced motility problems 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 and are an essential initial test performed in the better laboratory. A complementary test is the sperm mucus interaction test which examines the ability of sperm to swim through mucus.

Blood hormone tests are also frequently performed. Poor testicular function can reduce testosterone levels which in turn impairs sex drive and energy levels. The FSH (Follicle Stimulating Hormone) test gives an indication of the amount of sperm being produced. In normal men or those 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 level rises progressively.

A zero sperm count 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 readily clarifies whether sperm are present in the testis. In some cases of blockage, further tests such as ultrasound of the prostate and bladder region is performed.

Finally in men with very poor sperm production who are considering using the new 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 to their future children. One involves counting the number of chromosomes and the other looks for damage to the male, or Y, chromosome, which 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.



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