I get questions from non-lab people as to why we can't refreeze thawed plasma.  Does anyone have an answer about the science behind the regulations?  Did they test it once or did they just extrapolate from not refreezing thawed meat?  Or is it because you couldn't ( or wouldn't want to) control how many times it was thawed and refrozen?  Or just blood banker paranoia?  They've got me curious now.

Mabel, are you referring to large bags of plasma that are intended for infusion or are you asking about small tubes of plasma used for testing?

In either case - specimens or units - I am pretty sure that even one freeze/thaw cycle degrades some fibrinogen, and possible other coagulation factors.  So doing it over and over is not a great idea.

 

Scott

What Scott said; plus there is the practical side of documenting in the Blood Bank Information System.  I know our system wouldnever let us thaw a frozen plasma more than once. 

I meant plasma units.  I know that regs don't allow refreezing but I don't know what science the regs are based on.  I agree that Scott surely has it right, but how do we know this fact?  Did someone publish a study in 1942?

http://www.ncbi.nlm.nih.gov/pubmed/2505413

 

http://www.ncbi.nlm.nih.gov/pubmed/12823746

 

http://www.ajts.org/article.asp?issn=0973-6247;year=2013;volume=7;issue=1;spage=11;epage=15;aulast=Philip

 

That's an interesting question. A google search pulled out some relevant articles but it looks like they're saying refreezing isn't terrible.

From a pure common sense standpoint; the same reason you can't refreeze thawed meat, cooked or not. 

Specimens frozen for various coagulation tests are not to be refrozen once thawed per manufacturer's recomendations. 

 

As for refrozen and thawed meat or plasma, I am sure that the flavor is somewhat degraded in either case.

 

Scott

Refreezing meat causes the tissue to break down do the the intracellular ice crystal formation so the freeze - thaw - freeze - thaw cycle will cause additional tissue destruction with each cycle.  Not a lot of tissue in plasma but I can under stand the concern for fibrin.  I have no idea how the cycle would effect coagulation factors.  I'm not sure what the problem with re-freezing specimen plasma would be.  I haven't read the above referenced articles so I don't know if they address the issue or not.

Edited July 10, 201411 yr by John C. Staley

I once left my freezer door partially cracked at home while full of food.  It was that way for almost a week before I noticed.  By the time I opened the door to get some steaks out to cook for dinner I noticed everthing had thawed completely but was still cold to the touch so I took out the steaks and closed the door hoping for the best for everything else.  I cooked the steaks and they were fine.  A few days later I took out some ground turkey and let it thaw in my refrigerator over night.  When I opened the package to cook it the next day it smelled horrible, as did the rest of the meat that was previously defrosted and refrozen.  I lost the entire freezer full of food.  That's what my earlier comment was referring to.

So refrozen cow OK, refrozen turkey, not so OK. 

 

I imagine refrozen fish would be even worse!

 

Scott

 

Specimens frozen for various coagulation tests are not to be refrozen once thawed per manufacturer's recomendations. 

 

As for refrozen and thawed meat or plasma, I am sure that the flavor is somewhat degraded in either case.

 

Scott

 

I hate it when my plasma tastes yucky. LOL. Really though, this is a very interesting thread.

So refrozen cow OK, refrozen turkey, not so OK. 

 

I imagine refrozen fish would be even worse!

 

Scott

Well, the cow was not really "re-frozen".  I took it out and cooked it when I noticed the door partially cracked and the food defrosted.  The other stuff was later after I refroze it.

The issue is that you face two separate problems. 1) Sufficiently describing the effects of repeated freeze/thaw cycles on the product and demonstrating that it maintains the clinical utility that is expected. This would lead to defining an expiration based on cumulative thawed time and number of freeze/thaw cycles. 2) you need to identify a tracking mechanism that can ensure that the defined limit on cumulative thawed time/number of freeze/thaw cycles is not exceeded.

Which brings us to the 3rd and biggest obstacle: Who has time for all that and does the investment of resources deliver a payoff that is worth it??

Edited July 15, 201411 yr by JEMarti