Expert's Perspective

Is it safe to ship cryopreserved eggs (and embryos)?

This is becoming a popular question as more patients relocate and want to ship their eggs to a new clinic, use eggs donated from out-of-state and as clinics change their preferred freezing methods, which in some ways shrink the margin of error – we’ll get to that in a second.

Back to the original question, let’s have a look at the data within our own clinic. The below table shows patient (recipient) outcomes when vitrified donor oocytes were used either from an “in house” donor (“Non-Shipped Eggs”) or from an “outside” donor (“Shipped Eggs)”. All the main outcome parameters demonstrate that shipping is safe. Unfortunately, there is no national data to pull from and so this is the best we have for now.

Why Vitrification Matters & The Transportation Process

Vitrification is a far more efficient method to cryopreserve oocytes/embryos than slow-freezing, and there is a good chance your fertility clinic will use it. However, vitrification is a demanding process and requires that eggs/embryos be handled with a lot of care. One has to ensure that their temperature stays below -120 Celsius otherwise those eggs/embryos become damaged. In comparison, slow-frozen cells are able to tolerate a brief temperature rise up to -20 Celsius degree.

For long term storage, cryopreserved oocytes/embryos are typically kept in cryo-storage tanks that are filled with liquid nitrogen (LN). The temperature of liquid nitrogen is -196 Celsius. At that very low temperature all biological processes of a cell are suspended, and consequently, oocytes and embryos can be kept for years or decades, and still be used. However, it’s critical that during this period the temperature is kept stable which is why clinics have to constantly refill their storage tanks with liquid nitrogen.

So how do we ship eggs/embryos that need to be constantly kept well below of -120 degrees to another county, state or continent? At least down here in Atlanta we don’t have too many -120 degree days and when it comes to shipping eggs/embryos, the elements are always working against us.

First, we remove the eggs/embryos from the tank and place them in a “shipping dewar” to keep them cold. Unfortunately, we can’t fill that dewar with liquid nitrogen because the FAA refuses to let planes fly with it onboard. To get around this, the inner surface of the dry shipper contains “retention foam” that acts like a sponge, and is able to absorb some liquid nitrogen, releasing only vapor (but not the liquid of the nitrogen). If properly prepared (emphasis on the “properly”), this dry shipper can maintain a low temperature between -150 and -190 Celsius for several days (or even over a week), which should be sufficient for transporting the eggs/embryos.

Most clinics entrust FedEx or UPS to pick up the container and deliver it to the recipient clinic. Both companies do a lot of this type of work and have an excellent track record. Finally, the receiving clinic unpacks the container and places the eggs/embryos in their own storage tanks (with liquid nitrogen) until the patient is ready to use them.

How common this is?

I haven’t seen figures but I’d estimate that every year there are about 1,500 - 2,500 samples shipped between clinics. Most of this are vitrified donor eggs sent from egg banks to clinics. And for historical context, we’ve been shipping slow-frozen embryos since the late eighties. In short, our field has a ton of experience doing this.

Do all clinics accept eggs/embryos from all other clinics?

Usually, every clinic will accept cryopreserved eggs/embryos from any other clinic. In my 20 years doing this, I’ve never heard of a clinic refusing to accept embryos/eggs from another clinic. The only exceptions I can think of have been when the shipping clinic’s “documentation” was not in order.

How do I know if my clinic is good at shipping or receiving eggs/embryos?

Shipping and receiving eggs/embryos is kind of a commodity and all clinics should be able to do it correctly. It’s probably unrealistic to expect clinics to provide you with data on how well their sent, or received, eggs/embryos performed because most don’t have the volume for real comparison.

What does this cost roughly and is there any way to save money?

If the distance between the two clinics is short (for instance, if both clinics are located in the same city), then one can consider “hand delivery” by the patient who owns the eggs/embryos, which might cost almost nothing.

The cost to ship eggs/embryos longer distances within the U.S. is around $200 - 400 which really equates to the UPS or FedEx charge. But this varies depending on the arrangement the shipping clinic has with the shipping companies. And yes, some clinics will charge beyond what they pay Fedex or UPS. Then there are the clinics that simply won’t ship, period. In this case the patient has to contract directly with a shipping company (for instance Cryoport) that will oversee all of the shipping logistics (providing a well-prepared dry shipper, etc.), however, and as you might expect, this is more expensive.

Shipping internationally can cost a $1,000 or more depending on the destination. Shipping internationally involves all sorts regulations and customs paperwork and so there are only a handful of companies experienced enough to do this efficiently.

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