Andrology: Sperm Volume & Concentration
Part 2: Sperm Volume and Concentration (Sperm Count)
When the Andrologist determines the sperm count, two factors are involved, sample volume and sperm concentration. The total sperm count is the product of the sperm concentration (million/milliliter) multiplied by the sample volume (milliliters). Together, these two values tell us how many total sperm are present in the ejaculate. The World Health Organization (WHO) has determined the normal ranges for sample volume, concentration, and total sperm count.
Volume – The average volume of an ejaculate is between 1.5-5.0 milliliters (ml). Lower volumes are sometimes associated with blockage and/or retrograde ejaculation (ejaculation that refluxes into the bladder).
Concentration – The normal sperm concentration is ≥20 million sperm per milliliter of semen. Decreased counts can indicate abnormal or impaired spermatogenesis or blockage while increased counts are often found in cases of prolonged abstinence.
Total Sperm Count – The World Health Organization has determined the lower reference limit (2.5th percentile) to be 39 million sperm per ejaculate.
This total sperm count is clinically relevant due to a correlation between increasing pregnancy rates and total sperm count during assisted reproduction procedures, as demonstrated in the graph.
While it is possible to achieve pregnancy in couples below normal total sperm counts, additional procedures such as ICSI (Intra-Cytoplasmic Sperm Injection), where a single sperm is injected into the egg to facilitate fertilization, may be necessary.