A cryoshipper — also called a dry shipper or sample shipper — is a specialist cryogenic transport vessel that maintains biological samples at approximately -190 degrees Celsius during transit without containing free liquid nitrogen. The absence of free liquid nitrogen is what makes a cryoshipper safe for air transport under IATA regulations, which prohibit the carriage of free cryogenic liquids on commercial aircraft.

A cryoshipper achieves its cryogenic performance through an absorbent material — typically a porous foam or fibre matrix — that lines the interior of the vessel neck and walls. Before use, the cryoshipper is charged by filling it with liquid nitrogen and allowing the absorbent material to saturate fully. This typically takes between four and eight hours. Once saturated, the free liquid nitrogen is poured out, leaving the vessel in a vapour phase state at approximately -190 degrees Celsius within the sample cavity. Samples are loaded immediately before transport, and the vessel is sealed and consigned.

The holding time — the period during which the cryoshipper maintains cryogenic temperatures — ranges from approximately 24 to 96 hours depending on the model, ambient temperature, and charging quality. Cryoshipper selection must consider holding time relative to the maximum anticipated transit duration including delays. A cryoshipper providing only 24 hours of holding time is not appropriate for an international shipment where delays are possible.

For inter-clinic embryo transfer in the UK and cross-border reproductive care internationally, the CryoStork V2 from Cryolab is a 2-litre compact dry shipper purpose-designed for reproductive sample transport — embryos, oocytes, and sperm straws. Its IATA compliance, reliable charging protocol, and vapour phase performance make it the standard tool for inter-clinic embryo transfer.

A temperature data logger placed inside the cryoshipper for every clinical transfer provides the documentary evidence required by the HFEA that cryogenic temperatures were maintained throughout the journey. For HFEA-licensed facilities, maintaining this temperature record for every embryo transfer is a regulatory requirement, not optional documentation.

Source: IATA Dangerous Goods Regulations, 65th Edition, 2024. HFEA Code of Practice, 9th Edition, 2023. BCGA Code of Practice 27: Transportable Vacuum Insulated Containers, 2013.

Further reading: Cryoshipper Guide | CryoStork V2 | Liquid Nitrogen Tanks