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GLOSSARY

Post-thaw analysis

A post-thaw analysis is a test in which a small portion of your pre-analyzed sperm sample is frozen, thawed, and reanalyzed, to assess how well it will survive cryopreservation. Post-thaw analysis gives the best estimate of how many motile sperm you’ll have when using your frozen sperm sample in the future.

What is a post-thaw analysis?

A post-thaw analysis is a test that can assess how well your sperm will survive cryopreservation (freezing). The test involves freezing a small sample of your sperm, then thawing it to ensure that a sufficient number of healthy sperm are still present.

This evaluation is important because not every sperm cell will make it through cryopreservation and thaw, resulting in potentially fewer sperm being available for use in assisted reproductive techniques. A post-thaw analysis gives you a realistic estimate of how many sperm you’ll have after they’re thawed.

Studies have shown that between 82% and 85% of sperm generally survive thawing after up to 10 years of storage. Research has also found that freezing and thawing reduced sperm motility.

Process of a post-thaw analysis

After a semen analysis, the sample is frozen. A cryoprotectant is added to the sperm to help preserve them during the freezing process, then the mixture is placed in cryovials, cooled, then frozen in liquid nitrogen at -196ºC.

For the post-thaw analysis, a small sample of the sperm will be thawed at 37ºC, then undergo a second semen analysis to check for remaining sperm count and motility.

What a post-thaw analysis can tell us about male fertility

Fertile men typically release at least 39 million sperm per ejaculation, and a minimum of 10 million sperm is recommended to achieve a pregnancy through intrauterine insemination. It’s likely that sperm from people with normal semen parameters will be sufficient for fertility treatments, even after cryopreservation and thaw.

In people with extremely low sperm counts or poor semen parameters, however, a post-thaw analysis may reveal that very little sperm will be viable after thawing. This may occur not only because of the small initial number of sperm, but because the sperm is less healthy and well-suited to survive.

Regardless of your original semen parameters, the results of the post-thaw analysis can help you and your medical provider understand the quality of your cryopreserved sperm and prepare for fertility treatments after thawing.

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