The semen analysis or seminogram is a complementary test used to assess seminal quality. The parameters that must be taken into account when doing it and their normal values have been defined by the World Health Organization (WHO). This is really important because every correctly performed semen analysis or seminogram will have the same parameters, measured in the same way. In this way, the different semen analysis or seminograms that a man may have performed in different centres throughout the world can be evaluated and compared with each other.
The parameters that are measured in the semen analysis or seminogram are the following:
- Macroscopic parameters the appearance of the semen, the volume of the ejaculate, the pH and the time it takes for the semen to liquefy (go from its usual dense white appearance to being a liquid similar to water).
- Sperm concentration the number of sperm per ml of semen. This value must be at least 15 mill/ml. If the sperm concentration is less than this limit, it is called oligospermia.
- Sperm motility number of motile sperm in the semen sample. Sperm motility is usually expressed as a percentage of total sperm. We speak of progressively motile spermatozoa (that progress, that moves forward, non-progressive (that move, but do not progress) and immobile (that can be alive or dead). The union of spermatozoa is used as a reference value progressive and non-progressive (a + b). The sum of these percentages must be at least 40%. In addition, progressive motility must be at least 32%. Those samples that present motility below the established parameters are diagnosed with Asthenospermia.
- Percentage of normal shapes It is very common for men to be surprised to see that in their ejaculate very few sperm are considered normal. Actually, this is a normal fact, typical of the human semen sample, in which values of 5-10% of normal sperm are absolutely normal. In fact, the WHO considers semen to be normal when it has at least 4% of its sperm are normal. The low number of normal sperm is called teratozoospermia.
In recent times, different technology has been developed to assess other parameters in the seminal sample, so that it has been possible to determine that samples that we would have diagnosed as normal are not actually normal. For this reason, some centres have generated advanced, extended semen analysis, where other parameters are measured. Some of them are discussed below:
- Apoptosis In any sperm sample, it is possible to find spermatozoa that are not useful for fertilizing the ovum, so they enter apoptosis. Thus, a sperm destined to die, indistinguishable for a biologist from another in full activity, could be selected to microinject an oocyte, the result of this fertilization being at least suboptimal. At present, it is possible to detect apoptotic sperm by flow cytometry, and if their number is excessive, there are also techniques to separate these sperm from the rest, so that they cannot be selected during fertilization in the laboratory.
- Sperm DNA fragmentation the main function of a sperm is to deliver its genetic load, its DNA, to the oocyte. To do so, you must go through many difficulties and in the process, this DNA could be damaged. Also, to avoid this damage as much as possible, the DNA of a sperm travels packed by different proteins. A failure in their function would make the DNA more exposed and damage it. In general, the oocyte tends to repair sperm DNA damage, although the efficiency of the process will depend on the age of this oocyte. In any case, this can only occur when there is a basis for the repair of DNA strands, that is, when the fragmentation is “single-stranded”, and when the damage is not excessive.
Nowadays it is possible to measure the percentage of Esperam with fragmented DNA in a sample and there are treatments to improve this percentage if necessary or to select non-fragmented sperm.