In approximately 30% of couples attending for infertility investigations, ‘a male factor’ is thought to be the likely cause of the infertility. In a further 20% of couples, factors in both the man and the woman are thought to be relevant. It is very important therefore for the doctor to evaluate both partners when considering the reasons for, and the most appropriate treatment for a couples’ infertility.
After an appropriate history has been taken by the consultant, the main component of the investigation of the male is a semen analysis.
This involves a laboratory assessment of a man’s ejaculated semen sample.
Where and when should a sample for semen analysis be produced?
So that we can ensure that samples reach the laboratory in optimum condition, gentlemen are asked to attend the clinic and produce a sample for analysis in a private, designated room adjacent to the laboratory. In some circumstances it can be arranged for samples to be brought into the clinic for analysis, providing that they are presented within 1 ½ hours of production.
Samples are generally produced by masturbation or on occasion by intercourse using a special condom without a spermicide (provided by the clinic).
A semen analysis should be carried out following 2-3 days of abstinence from intercourse or masturbation. Shorter or longer periods of abstinence could result in a mis-representative result.
What is assessed in a semen analysis?
Various parameters are assessed on a semen analysis and these are compared with World Health Organisation standards (WHO, 1999). The main features of a semen sample that are assessed are outlined below.
- The volume of the sample The WHO (1999) quotes 2 millilitres (about half a teaspoon) or more as the normal volume for an ejaculate.
- The number of sperm that are present in the sample. This figure is often described as the ‘count’, although it is actually the ‘concentration’ of sperm, i.e. the number of sperm in each millilitre of the sample. The WHO (1999) quotes 20 million sperm per millilitre or more as a normal count.
- The percentage of the sperm in the sample that are swimming (the motility) and how well the sperm are swimming (the progression).
The WHO (1999) states that in a normal sample, 50% of sperm or more should be actively swimming.
- The proportion of sperm that have a normal size and shape (the morphology).
Morphology can be assessed by different methods and our routine semen analysis involves examining a fresh sample. By this test, in a normal sample, 35% or more of the sperm would be expected to show a normal morphology.
- The presence of anti-sperm antibodies on the sperm. The WHO (1999) quotes binding of anti-sperm antibodies to 50% of sperm as clinically significant, that is, of potential impact on fertility.
Semen DNA Fragmentation
Sperm DNA is by nature packaged in a different way to that of other cells in the body. In sperm cells, DNA is arranged in very tight organised loops so that it can be carried safely to its final destination – the egg. Semen protects sperm from several hazards along the journey. Oxidative stress is related to the integrity of the packaging of the DNA of the sperm. Certain reactive oxygen species can "nick" the sperm DNA under certain circumastances and cause dNA fragmentation. Sperm DNA can be damaged in this way.
If such a sperm is accepted into an egg for fertilisation, errors in DNA transcription and synthesis can occur when maternal and paternal DNA join.
To assess this this problem we employ the Sperm DNA fragmentation test. This test may reveal high susceptibility toward DNA damage, or actual DNA fragmentation already present in sperm. If this index is elevated (generally above 30%), the fertility of that specimen is reduced.
This testing identifies DNA strands in sperm that are susceptible to fragmentation. Also detected is highly stainable DNA, which may indicate altered packaging of sperm DNA. Again, this is important to know because sperm with fragmented DNA are more likely to casue a problem in the resulting embryos, compared to those with normally packaged DNA.
Treatment includes maintaining appropriate temperature for the scrotum, giving up smoking, reducing your weight and ensuring that any medication that you are on does not cause DNA fragmentation.