Everything you need to know about cryo transport

Pamela Matthews, a passionate Clinical Embryologist with nearly 30 years experience caring for embryos, eggs and sperm, now runs a courier service for frozen eggs, embryos and sperm and explains what’s involved and what you need to know.

So what is cryo transport?

Cryo transport is a unique service in that the viability of the reproductive material prior to transportation cannot be guaranteed.  Nor is it possible to assess if the service you provide has in any way compromised the viability unless a catastrophic event has occurred.  It is only when a third party stores and thaws the material that the condition of the material can be assessed.  Due to the chain of transfer between parties it is impossible to assign liability for any damage.  Added to this is the fact that even if the chain of storage is faultless, survival post cryopreservation is still not guaranteed.  Aside from the actual cost of the transport and treatment there is an enormous emotional investment in the reproductive material.

These unique circumstances confer a great responsibility on the courier to be vigilant about risk management and quality assurance and control.

All cryopreserved reproductive tissue is stored either directly in large tanks of liquid nitrogen which has a consistent temperature below -190°C, or in liquid nitrogen vapor which varies between -160°C and -190°C.

Most eggs and embryos are stored in liquid nitrogen as the current cryo-preservation technique of vitrification requires them to be in as little as 2μl of media, the average volume of a drop of water from an eye dropper is 30μl. 2 μl of media would thaw at room temperature in 10 seconds, destroying the tissue. Sperm is frozen in anything from ½ ml in a straw up to 2 ml in a vial making it far more robust.

At this point l will declare my hand and state that l have just launched my own courier company.  After nearly 30 years in an IVF lab l was looking for a new challenge and life as a courier was a good match for my expertise and love of travel.  I have applied the principles of risk management, accountability and ethical practice demanded in an IVF laboratory to my operating procedures as an IVF courier.  Cryo-transport is still unregulated despite the risks it carries.

All cryo-preserved reproductive tissue is transported in a dry shipper, approved by the International Air transport Association (IATA) to be carried on aircraft. 

However, there is an array of services offered.  The most basic transports the dry shipper as cargo.  The other end of the spectrum is an exclusive hand carry service, where a dedicated courier carries only your tissue from door to door.  The shipper is sealed at collection and the seal broken by the receiving clinic, the shipper is not x-rayed or opened during security screening.  Clearly the price between the levels of service will also vary significantly.  As there are no industry standards and the companies are not regulated and audited, only the client and the service provider can determine the level of service provided.

Dry shippers come in varied sizes, each size will maintain the temperature for a specified length of time.  Dry shippers are very similar in construction to the storage tanks used in an IVF laboratory except they are lined with a foam, which absorbs the nitrogen.  There must be no liquid nitrogen in the shipper when it is transported on an aircraft.  The nitrogen evaporates over time until a critical volume is reached, at this point the temperature will start to rise at quite a rapid rate.  Each tank is certified to maintain the temperature at the requisite -190°C for a specified period of time, however, there can be a significant variation in the performance of shippers even in comparison to the same model and make.  Additionally the performance of any shipper can drift overtime.

The performance of the shipper can be compromised in two ways, by the breakdown of the foam or a build up of moisture from condensation. Both result in a reduced volume of liquid nitrogen being absorbed and a consequent reduction in the hold time or the period of time the shipper will maintain the temperature at  -190°C.  This can be easily managed by verifying the performance of the shippers at regular intervals, generally every 6 months.

A temperature data logger should accompany all consignments and the data downloaded and provided to all parties, the client, the dispatch clinic and the receiving clinic.  This is the only method of quality control.  As a proprietor and courier l want to assure myself that l have maintained the temperature throughout the journey, it is my conscience and only insurance policy and it allows me to sleep at night. The data must be stored in a secure manner that allows it to be accessed and matched to any consignment.  If you are transporting perishable food you must monitor and record the temperature but there is no such requirement for human gametes/embryos.

Sometimes there is more than one consignment in a tank, which is a safe way of minimizing what is a costly service, however it usually involves opening the tank a number of times to add or remove samples.  This is the most vulnerable time for tissue in the tank and it is critical that the data logger remains with the samples recording the temperature of the samples throughout this vulnerable period.   You must be able to show a continuous temperature log for every sample for the entire period they are in your care.

In an ideal world l would like to have security declare that the shipper was not x-rayed.  Unfortunately, we do not inhabit Utopia and l think this would be very difficult to achieve.  People in authority are often very reluctant to take responsibility in this situation even though they are following protocol.  Australia and South Korea are unique in that they require you to obtain an exemption from a Government Department prior to clearing security.  I personally like this system as it provides you and your client with surety.

If you are transporting sperm well in advance of a treatment cycle and if a replacement sample is readily available then the basic service is a viable option.  There is usually a number of vials/straws from a single ejaculate and only one required for a treatment cycle.  The receiving clinic can thaw a vial/straw on receipt and assess the quality. A second sample can be dispatched if necessary.

Eggs and embryos are a very different proposition. 

Generally, they are very precious and only when they are to be used for treatment are they thawed and evaluated.  There are no second chances; the viability can be compromised with any deviation in temperature.  Only the consumer can decide how far their resources can be stretched and the value they place on this reproductive tissue.

The greatest concern with an unaccompanied consignment is the handling of the shipper by unknown individuals.  For the shipper to perform optimally it must always remain up right.  The temperature hold time can be halved if the tank is on its side.

A data logger is a valuable tool for monitoring the temperature but it only informs you when you already have a problem, giving you a very small window of opportunity to manage it.  In the recent validation l did on my small tank, when the critical weight was reached it took only 12 hours for the temp to rise from -185°C to -135°C, from safe to significant comprise of the tissue.  In the following 12 hours the temperature rose to +11°C, which would result in total destruction of the tissue.

Graph of temperature over time, for my dry shipper.  The change in weight is linear throughout.

As an additional monitoring tool l weigh the shipper, which acts as a fuel gauge.  There is a dry weight, a fully charged weight and a critical weight when the temperature begins rise.  It is essential that you know what each one of these is for each shipper as there is significant individual variation.    When the critical weight is reached, the change in weight over time is the same but the rise in temperature is dramatic.

Weight is also a useful parameter for verification and troubleshooting.  You must record these parameters when the shipper is purchased; any shift is an indication that there is either a moisture build up or a break down of the foam.  I can calculate how long the shipper can maintain the optimum temperature from its weight.  If I am unfortunate enough to be delayed in transit I can easily determine how long l have before l would require an emergency recharge of liquid nitrogen and plan accordingly.

When the appropriate level of service has been decided upon a service provider must be contracted.  The following questions may be informative during this process.

Does the service provider use a data logger?

Does the service provider supply a copy of the data?

How often are the shippers verified?

Is there evidence that the shipper has not been x-rayed?

Is it a hand carry service under the control of a courier at all times?

How many clients will be carried during the consignment?

How often will the shipper be opened during the consignment?

Will the courier be overseeing the loading and unloading of samples?

Will the temperature of the samples be monitored if the shipper is opened?

How long will the journey take from collection to delivery?

There is a large variation in service provision and price. However, the level of service provision and the cost is not always proportionate.

If you would like to discuss any of these issues further please feel free to contact me via my website here.

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