A sperm viability test determines the percentage of live sperm in a semen sample. This test is crucial for assessing male fertility, particularly when sperm motility (movement) is low. It helps differentiate between non-motile sperm that are alive (but perhaps unable to move) and those that are dead.
Why is Sperm Viability Testing Important?
Sperm viability is a key indicator of male fertility. Even if a man has a sufficient number of sperm (sperm count) and some motility, a low viability rate suggests a problem. A low percentage of live sperm significantly reduces the chances of successful fertilization.
- Identifying potential issues: Low viability can indicate underlying health problems affecting sperm health.
- Guiding treatment decisions: The results help doctors determine the appropriate course of treatment for infertility.
- Evaluating the effectiveness of treatment: Viability tests can monitor the success of fertility treatments.
How is Sperm Viability Tested?
Two primary methods are used to assess sperm viability:
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Dye exclusion assays: Live sperm possess intact cell membranes that prevent certain dyes from entering. Dead sperm, with damaged membranes, absorb the dye, making them identifiable under a microscope. This is a common and relatively simple method. (Reference: Give Legacy fertility analysis, Sperm Motility & Viability | Male Fertility Lab | Chip Muller)
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Hypo-osmotic swelling (HOS) test: This test assesses the sperm membrane's functional integrity. Live sperm swell in a hypo-osmotic solution, showing their ability to react to changes in osmotic pressure; dead sperm do not. (Reference: The hypo-osmotic swelling test: Is it a sperm vitality or a viability ...)
When is Sperm Viability Testing Indicated?
Sperm viability testing is typically recommended when:
- Sperm motility is low: Less than 5-10% motility often prompts a viability test to determine if the non-motile sperm are alive. (Reference: Semen analysis and sperm function tests: How much to test? - PMC, Sperm viability testing is used to determine if nonmotile sperm are alive or dead and are indicated when sperm motility is less than 5%-10%)
- Diagnosing conditions like primary ciliary dyskinesia: This condition affects cilia (hair-like structures) and can lead to low sperm motility despite high viability. (Reference: Sperm viability testing is used to determine if nonmotile sperm are alive or dead and are indicated when sperm motility is less than 5%-10%. They are useful in primary ciliary dyskinesia where ultrastructural defects in sperm flagella result in absent or extremely low motility but with high viability.)
- Investigating infertility: It's a valuable component of a comprehensive semen analysis for male infertility workup. (Reference: Semen Analysis - StatPearls - NCBI Bookshelf)
Reference Ranges
A typical reference range for sperm viability is ≥50%, meaning at least 50% of the sperm in the sample are alive. However, this can vary depending on the laboratory and the specific test method used. (Reference: Sperm Motility & Viability | Male Fertility Lab | Chip Muller)
