Causes of male infertility
Male infertility is very common, affecting about one man in twenty. Male factor is present in almost half of all infertile couples and 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 testis have 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 that occurs inside each testis. For most infertile men it is only this process that is at fault and 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 (morphology). 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 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. No treatment for men to improve sperm counts is likely to become available. IVF techniques offer hope though, 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:
1. Obstruction to the passage of sperm from the back of the testis to the outside can result from blockage or absence of the vas deferens. Common causes include, obviously, vasectomy, but any history of injury, and other surgery or sexually transmitted disease may be important.
2. 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 Barbados Fertility Centre.
3. The testis can be damaged by a wide number of treatments including chemotherapy or repeated X-Ray therapy.
4. 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.
5. 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.
Finally studies have shown that sperm counts have declined worldwide. The alleged change is quite small (about 15%) and no cause has been confidently identified, however it is believed to be an environmental factor.
In conclusion 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 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.
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 four days of sexual abstinence.
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 40% 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 our laboratory. Another indicating test is the sperm mucus interaction test, which examines the ability of sperm to swim through mucus.
Blood hormone tests are also 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. This is a standard blood test that should be performed routinely if a severe male factor is diagnosed.
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 by our embryologist, 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 can be performed by a Urologist.
In conclusion, thorough clinical assessment of the man and the performance of a range of specialized hormone and sperm tests are needed to for full evaluation.