Though the exact details remain unclear, the recent events highlighted in the news have certainly raised concerns regarding the management and safety of cryopreserved specimens. After cryopreservation, oocytes or embryos are stored in tanks which must be kept filled with liquid nitrogen in order to maintain proper storage temperature and conditions. All liquid nitrogen storage vessels have a natural/normal rate of liquid nitrogen loss, and thus have to be monitored and replenished with liquid nitrogen regularly. At FCNE, we monitor ALL of our liquid nitrogen storage tanks daily, 7 days a week, without exception. This is part of our daily quality control and assurance routine in the laboratory.
In addition to this daily assessment, all tanks are replenished with liquid nitrogen twice a week. This ensures tanks have maximal levels of liquid nitrogen at all times. Keep in mind these tanks can maintain proper temperature with much lower liquid nitrogen volumes, but our laboratory protocol is to have the tanks full at all times. In the rare event that a tank may fail, this would ensure longest duration of maintaining temperature and time to relocate any specimens to a new tank. A tank failure, if it occurs, is likely the loss of the vacuum insulated core vessel. Loss of insulation greatly accelerates the usage of liquid nitrogen. With our daily monitoring however, we would be aware of such an event immediately.
Terms such as “freezers” that have been used in the news reports, are incorrect regarding oocyte and embryo storage. This suggests or implies a system that utilizes electricity to create proper storage temperature and conditions. Only liquid nitrogen can achieve the proper conditions necessary. There is no “backup” like a generator or battery, but a spare tank is always available if ever needed.
We are very confident in our system of maintaining cryopreserved inventory. We feel our standard operating procedures error on the side of excessive caution and vigilance. We do not rely on automatic filling systems or alarms to initiate action as these can lead to complacency and false sense of security.
We are currently researching the latest technology in tank monitoring systems to add an additional layer of safety and confidence. Your precious eggs and embryos are always safe and protected with the Fertility Centers of New England. If there are any further questions or concerns regarding cryopreserved storage, please do not hesitate to reach out to me.
Peter Wieckowski, Ph.D.
Fertility Centers of New England