Definition - What does Semen Volume mean?
Semen volume is the amount of fluid in the ejaculate that is mainly comprised of seminal plasma, the fluid medium in semen that suspends the sperm cells. Normal semen volume is 2-6 milliliters per ejaculate. Semen is the transport medium for sperm that provides the nutrition to the sperms while protecting it from the outside environment as sperm travel through the vagina and uterus to the fallopian tubes to fertilize an egg. Inadequate semen volume can hinder the ability of sperm to fertilize an egg leading to male infertility.
FertilitySmarts explains Semen Volume
Seminal plasma primarily makes up the semen volume with a minor contribution from the sperm cells. About 75% of seminal plasma is produced by the seminal vesicles, which are 2 glands located behind the bladder. Nearly 20% of the seminal plasma is produced by the prostate gland while the testis and bulbourethral glands, another pair of glands in the male reproductive tract, also have a minor contribution to seminal plasma.
The volume of semen can affect the overall quality of sperm cells. When the sperm cells are present in the semen in normal amounts while having a low semen volume, it will make the sperm concentration high leading to a competition for nutrients. If sperm cells receive suboptimal nutrition, they can lose their motility and thus the ability to swim.
The alkaline medium in the semen helps to neutralize the acidity in the vagina to make the environment suitable for sperm cells to survive. If the semen volume is low, the alkaline content may be inadequate to neutralize the acidity of the vagina, which can kill or impair the activity of sperm cells making them unable to start their journey towards the fallopian tubes to fertilize the egg.
Abnormalities in the male genital tract causing reduced production, blockage to the flow of the ejaculate or retrograde ejaculation (the reversed flow of semen towards the bladder), can give rise to a low semen volume. Other abnormal conditions that can lead to a low semen volume include vitamin deficiencies (eg; selenium and zinc), low testosterone levels and obesity. However, it is normal for the semen volume to be low if a person ejaculates frequently.
A routine semen analysis evaluates semen volume and is a standard component when evaluating a male with infertility.