What Is Testicular Sperm Extraction and How Are TESE Samples Cryopreserved?

Testicular sperm extraction (TESE) is a surgical procedure used to retrieve sperm directly from testicular tissue in men who cannot produce sperm in their ejaculate. The cryopreservation of TESE samples presents specific challenges that differ from routine ejaculated sperm freezing, and the consumable and equipment requirements reflect those differences.

What makes TESE cryopreservation different

TESE samples typically contain very low numbers of sperm – sometimes only a handful of viable sperm within a larger volume of testicular tissue. The sperm retrieved are often immature and may have lower inherent cryotolerance than ejaculated sperm. This means the margin for error in the cryopreservation process is smaller, and post-thaw sperm recovery can be highly variable between samples and between patients.

The cryoprotectant preparation must be performed carefully given the low sperm numbers. In some cases, andrology laboratories opt to cryopreserve TESE sperm in very small volumes – including individual straws containing a single viable sperm or a very small number – to maximise the chance of recovering at least some viable sperm at thaw for each ICSI cycle.

Slow freezing vs vitrification for TESE

Most UK andrology laboratories use slow freezing with a controlled rate freezer for TESE samples, following the same validated protocols used for ejaculated sperm. There is growing published evidence that vitrification may produce better post-thaw recovery in very low sperm number samples, but validated clinical protocols for routine TESE vitrification are not yet widely adopted in UK practice.

The TESE cryopreservation decision is one of the highest-stakes consumable and protocol choices in andrology. When there are only a few viable sperm available and the patient cannot easily undergo a repeat surgical procedure, the quality of every step from sample preparation to storage to thaw directly affects whether the cycle can proceed.

Equipment and consumables

The CBS DigitCool controlled rate freezer supports the validated slow freezing protocols used for TESE samples in UK andrology laboratories. CBS High Security Straws provide the sealed, identifiable storage format appropriate for these high-value samples. For protocol and equipment advice, contact Cryolab or use CryoGPT.