Sperm freezing (semen cryopreservation or sperm banking) stores sperm at very low temperature for future fertility treatment. Men should strongly consider it before chemotherapy, radiotherapy or other treatments that may damage sperm production. It may also be useful before testicular surgery, when sperm counts are extremely low or fluctuating, before gender-affirming or fertility-suppressing hormone therapy, and when retrieved sperm are obtained during PESA/TESA/TESE/micro-TESE. Freezing does not guarantee a future pregnancy, but even small numbers of viable stored sperm can be valuable because ICSI can use very limited sperm quantities.

What is sperm freezing?

A semen sample is collected, analysed, mixed with cryoprotectant, divided into labelled storage vials and cooled using controlled laboratory methods before long-term storage in liquid nitrogen. If sperm cannot be ejaculated, surgically retrieved epididymal or testicular sperm can also be cryopreserved.

When sperm freezing is strongly recommended

When sperm freezing may be sensible even without cancer

• Cryptozoospermia or extremely low sperm counts that fluctuate between samples.
• Progressive decline in sperm concentration when future biological paternity is important.
• Before vasectomy when a man wants an additional fertility backup, after informed counselling.
• Before major surgery that may impair ejaculation or damage the reproductive tract.
• Before starting exogenous testosterone when future fertility may be desired—although the first question should be whether testosterone is truly indicated and whether fertility-preserving treatment is preferable.

How many samples should be stored?

More samples provide more flexibility, but the number depends on urgency, sperm quality and planned future treatment. ASCO 2025 advises collecting as many ejaculates as feasible before cancer therapy and notes that even one compromised sample can be valuable because ICSI uses very few sperm. A cancer treatment should not be dangerously delayed simply to achieve an arbitrary number of samples.

What if sperm count is already very low?

Do not assume the sample is “too poor to freeze.” With ICSI, even small numbers of viable sperm can matter. In cryptozoospermia, the embryology laboratory may need extended sperm search and specialised freezing methods. In azoospermia, the cause should be evaluated and surgical retrieval may be considered when appropriate.

Does freezing damage sperm?

Some sperm do not survive freeze-thaw, and motility may decrease after thawing. Modern cryopreservation is nevertheless an established fertility-preservation technique. The laboratory usually performs a test-thaw or assesses post-thaw survival according to its protocol.

How long can sperm remain frozen?

At liquid-nitrogen temperatures, biological activity is effectively halted. Successful pregnancies have been reported after many years of storage. Practical storage duration is determined mainly by consent, local law, laboratory policy and continued storage arrangements rather than a short biological expiry date.

Using frozen sperm later

The choice between IUI, IVF and ICSI depends on how much motile sperm is available after thawing and on the female partner’s fertility. Surgically retrieved sperm and very low-count frozen samples are usually used with ICSI.

Cancer: timing is especially important

ASCO recommends discussing sperm banking with pubertal and post-pubertal males before cancer-directed therapy whenever possible. Sperm collected before treatment is preferred because treatment can impair sperm quantity and DNA integrity even after the first exposure. Fertility preservation should therefore be discussed early, at the same time the oncology plan is being made.

Before cancer treatment, do not wait for a perfect sample

When chemotherapy, radiotherapy or fertility-threatening surgery is planned, sperm banking should be discussed before treatment whenever possible. Even a low-count or otherwise abnormal sample can be worth freezing because ICSI can use very small numbers of sperm. If time allows, more than one collection may increase the stored reserve, but fertility preservation should be coordinated so that urgent cancer treatment is not unnecessarily delayed.

Men should tell both the oncology team and fertility laboratory when treatment is due to start, because the timing of sperm collection matters more than trying to obtain an ideal semen report.

What to bring for consultation

Bring these if available:

• Current semen analysis.
• Cancer diagnosis/treatment plan or upcoming surgery details if relevant.
• Previous sperm-freezing inventory/report.
• Current testosterone or fertility-suppressing medicines.
• ID/consent documents requested by the fertility laboratory.
• Partner’s fertility plan if sperm will be used soon.

FAQs

Related reading

• Cryptozoospermia Explained
• Azoospermia: No Sperm in Semen
• Micro-TESE Surgery Explained
• TESA and PESA Explained
• Low Testosterone and Male Infertility
• Urologist in Latur

References

• American Society of Clinical Oncology. Fertility Preservation in People With Cancer: ASCO Guideline Update. J Clin Oncol. 2025 https://ascopubs.org/doi/10.1200/JCO-24-02782
• World Health Organization. WHO laboratory manual for the examination and processing of human semen, 6th ed https://www.who.int/publications/i/item/9789240030787
• European Association of Urology. EAU Guidelines on Sexual and Reproductive Health: Male Infertility. 2026 https://uroweb.org/guidelines/sexual-and-reproductive-health/chapter/male-infertility
• American Urological Association/American Society for Reproductive Medicine. Diagnosis and Treatment of Infertility in Men: AUA/ASRM Guideline (2020; Amended 2024) https://www.auanet.org/documents/Guidelines/PDF/2024%20Guidelines/Male%20Infertility%20Unabridged%20Final.pdf