What are the normal values of sperm parameters?
The WHO (World Health Organization) haspublished a series of guidelines as regards the sperm parameters that should beexamined in a semen analysis, and has established the normal referencevalues to determine if the results are normal or not.
Sperm parameters can be examinedmacroscopically and microscopically.
A macroscopic examination allows thespecialist to evaluate the basic characteristics of the sperm sample, that is,the ones that can be seen by the naked eye, without using a microscope. Thefollowing are key values:
Measured in milliliters (ml). Samples areconsidered normal if the volume is above 1.5 ml.
The sample needs to be liquefied for 20minutes prior to doing the analysis until it becomes totally liquid.
The normal color of the semen is yellowishto greyish. If the sample is too transparent, it may indicate the presence ofwhite blood cells (leukocytospermia). If it is too opaque, it is likely thatthe sperm count is high.
The specialist measures the length of thethreads formed by drops. Threads must break so that the sample can be examinedaccurately. A sample that is too viscose can indicate prostate problems.
The normal pH of semen ranges between 7 and8. Variations under or above this range are associated with infections.
If a macroscopic examination is moreassociated with the external traits of the semen and the fluids it is composedof, a microscopic examination focuses on all aspects related to the spermcells.
1. Sperm count
The total sperm count must be higher than15 million sperm per milliliter or 39 million per ejaculate in order to beconsidered normal.
2. Sperm motility
It is used to examine the percent of motilesperms in the sample, as well as the ones that are able to “swim” in terms ofrapidly progressive, slowly progressive, or non progressive. A sperm sample isconsidered normal when more than 40% of sperm are able to move and over 32% areable to make forward progress.
3. Sperm vitality
There exist many tests to determine whetherthere are dead sperm cells in the ejaculate: eosin Y dye test, hypo-osmoticswelling test, etc. For a semen sample to be considered normal, the percentageof live sperm should be above 58%.
4. Sperm morphology
Hematoxylin and Eosin stain is used toevaluate the morphology of a drop of semen. The sperms are examined one by oneto detect the presence of anomalies. Normal forms must be present in at least4% to consider that the sample is normal.
5. Presence of WBCs
In case white blood cells (WBCs) arepresent in the sample, the amount is examined under the microscope. If thepresence of WBCs or leukocytes is above 1 million/ml, it is an indicator ofinfections. This condition is knownas leukocytospermia or pyospermia.