Vapour phase storage holds cryopreserved samples above the surface of liquid nitrogen, in the nitrogen vapour column that sits above the liquid, at temperatures typically between -150°C and -190°C. Unlike liquid phase storage, where samples are submerged directly in liquid nitrogen at -195.8°C, vapour phase eliminates the cross-contamination risk that arises when samples from multiple patients share the same liquid nitrogen bath.
The cross-contamination concern is not theoretical. Published case reports have documented viral transmission between samples submerged in shared liquid nitrogen. HFEA and ESHRE guidance both acknowledge this risk. For any UK IVF clinic storing embryos from multiple patients in the same vessel — which is the norm in regulated embryo banking — vapour phase is the appropriate storage mode. The direction of practice in UK fertility clinics has been clearly towards vapour phase for embryo storage as a result.
Liquid phase storage remains appropriate for specific applications where the risk profile is different — sealed straw sperm banking in andrology units, for example, where the higher thermal mass of liquid phase provides a buffer against brief monitoring lapses. Cryolab’s CryoNest range is designed specifically for high-capacity vapour phase embryo banking. Contact Cryolab to discuss the right storage configuration for your laboratory.
