Definition - What does Sperm Concentration mean?
Sperm concentration indicates how many sperm cells are present in a unit volume of semen. It is usually expressed as the number of sperm per milliliter. According to 2010 World Health Organization (WHO) reference values for human semen characteristics, a sperm concentration of more than 15 million sperm per milliliter is considered normal. Having a low sperm concentration is a well-known cause of male factor infertility. A semen analysis is routinely performed to evaluate the sperm concentration in the semen of the male partner when a couple is evaluated for infertility.
Sperm concentration is also called sperm density.
FertilitySmarts explains Sperm Concentration
Sperm cells, after being deposited inside the vagina after sexual intercourse, need to swim a long way through the vagina, uterus and the fallopian tube to fertilize the egg. Although millions of sperm start this journey, many of the cells die on their way and only a few of them are able to reach the egg for fertilization. For this reason, the concentration of sperm in semen is very important for natural conception. If the sperm concentration is insufficient, the chances of a sperm making its way to the egg are lower, which can lead to male infertility.
A sperm count in a normal person can range from 40 - 300 million sperm per milliliter of semen. It is considered abnormal only if the levels fall below 15 million per milliliter, but men can still experience fertility issues with a higher sperm concentration if there are other abnormalities in the semen such as low semen volume or sperm quality.
An improper technique used to collect or store sperm that is used for analysis can give rise to a false low concentration, so a test that shows a low concentration of sperm is typically repeated to make sure there is no collection error.
Sperm concentration should not be confused with the sperm count, which means the number of total sperm cells in the semen sample collected. Sperm count is calculated by multiplying the sperm concentration by the volume of semen. The sperm count varies depending on the volume of the sample, but the sperm concentration always remains the same within the sample.