Male factors contribute to infertility in approximately 40% of those couples that are having difficulty conceiving a pregnancy. Therefore, despite its well known limitations a detailed semen analysis is an appropriate starting point of investigation for a couple who have not achieved a pregnancy within a reasonable time period.
Normally men produce approximately 1,000 spermatozoa every second, but the sperm count can vary markedly in both fertile and sub-fertile individuals. To make an accurate assessment of sperm quality scientists take a semen sample and analyse it under a microscope. From these samples they can then estimate the following:
| ||The concentration of spermatozoa and the total sperm count|
The percentage of motile (moving) spermatozoa and the total motile sperm count
The percentage of spermatozoa able to move quickly in a forward direction
How normal the shape of each sperm head and each sperm tail is
Whether the spermatozoa stick together and to what extent
The concentration of round cells (immune system cells, immature sperm cells without tails, and other cells of the genital tract that are found in the seminal fluid).
It is generally recommended that a man have at least two semen analyses collected two months or more apart to assist the doctor to recommend the best treatment option. The interpretation of a semem analysis varies. For instance, a single semen analysis can be affected by recent ejaculation or viral infection. Conversely a semen analysis which appears normal may be overestimating the quality of the semen in a man who has an abnormality of semen contributing to a couple’s infertility. Each case needs to be considered in the context of the couple and decisions are made according to the treatment preferences of the couple, the duration of infertility, the age of the female and other factors. Even with less than 5% normal spermatozoa in a semen sample, it is still possible to achieve a pregnancy.