There is not a day that goes by when I don't think about the security and safety of the embryos, sperm and eggs we have frozen in our cryopreservation or cryo tanks. I am on vacation this week and was out for a run and our tanks were on my mind. Our lab director would say an hour doesn't go by when he doesn't think about our tanks.
This past week two US clinics had problems with their cryo tanks putting hundreds of embryos, sperm and eggs at risk. A clinic in Cleveland and another in San Francisco experienced the terrible, horrifying event of tank failure. Tank failure means the tank's temperature rose or not enough liquid nitrogen was surrounding the frozen tissue. As a result the tissue could completely or partial thaw - damaging or even destroying it. It is unclear just how many of the frozen samples were damaged/destroyed - they will likely not know until the patients request they be thawed and used. The two clinics involved were reputable large clinics who presumably had good systems in place to prevent loss of tissue in (cryopreservation) tanks, but the systems just weren't good enough or are subject to failure. This is a worry for everyone.
What do we have at Olive to ensure this won't happen here? I asked our lab director, Dr. Salah to put into words our system and I quote him:
"We have multiple levels of redundancy to guard against any kind of failure at our cryo tanks. It is practically impossible for us to have this type of failure. We physically measure the level of liquid nitrogen in centimetres every morning in every cryo tank and record this level in our QC charts. We actually have the level of liquid nitrogen in every cryo tank every day for the last five years since we opened Olive. I can tell you today how many centimetres of liquid nitrogen on any tank at any day in the last five years. This is our record that nothing happened in the sort of US clinic incidents of the past week. All our tanks are topped up every few days if the liquid nitrogen falls below few centimetres from the top of the rim of the cryo tank but still well above the top of the canisters that contain the tissues. This is also documented.
All our cryo tanks are monitored 24/7 round the clock with a remote monitoring system that dials out to a dedicatedly lab cell phone held by embryologists on rotating basis. If the embryologist with the dedicated lab cell phone does not answer and acknowledge the call within five rings, the call rotated to the private cell phone of the lab director and if the lab director does not answer there is a rotation list of embryologists cell phones that our system dials out until the call is answered. These calls are answered within 10-20 minutes to investigate and correct the situation, sometimes a loose connection can trigger the alarm but we've never had a low liquid nitrogen level.
The cryo tanks are self contained, and if fully charged with liquid nitrogen can very easily last for couple of weeks without running low to the point of liquid nitrogen level falling below the top of the canisters that contain the eggs or the embryos/sperm. That is why it is astonishing to hear about these other clinic failures. We also have large cryo tanks the self fill automatically from a liquid nitrogen source. They are also subjected to the same rigorous QC and monitoring and we have the level of liquid nitrogen measured and documented every morning. "
I've had just a couple of patients ask if I had heard of the US clinic tank issues, as they were worried too. No wonder they worried. We all know how important frozen embryos, sperm and eggs are. I hope this explanation reassures you. We are doing our best with every technology and fail-safe available to keep tissues people have entrusted to us safe.