I work in the lab of a very large Boston hospital, the Blood Tansfusion Service to be particular. Apparently I guess that means that other hospitals will sometimes turn to us for reference to questions, which was the case tonight. A smaller but still urban hospital contacted us tonight to ask us a question regarding a problem with some expiration dates.
Plasma, separated from a whole blood donation, is frozen and stored in freezers until it is thawed for transfusion purposes. The expiration date of a frozen unit has always been one year (or 24 hours after thawing). The other hospital called us because they didn’t know if they were labeling their products correctly for the date of frozen expiration because next year is a leap year. So all the plasma units collected on 3/1/07, they were labeling to expire on 2/29/08, while all the units we collected on 3/1/07 are due to expire on 3/1/08.
Whenever we need to split hairs with questions like these we always turn to the Bible of the blood bank, which is the AABB Technical Manual. It states that frozen plasma expires twelve months from the date they are collected. So the only question is interpreting whether that means that once every four years our frozen plasma products have exactly one more day of life than the rest.
I actually have already decided what the answer is, but I was just curious what you guys thought and maybe if there is any debate over it. But in the end I really am looking for a factual answer.
Really? We’re worried about this? I can’t imagine that there’s a clock inside the blood that switches it off exactly at 8760 hours and 0 minutes. I say 12 months, which includes the Leap Day. In reality, it might be good for 14 months, or 15 months, 3 days and 25 minutes or 3 years. Obviously, one wants to draw the line on the conservative side, but I really don’t see where a .27% difference is going to be significant.
The lawyers might have a different factual answer, however, and one desiring to keep their job should probably check with them.
I once ran into a similar problem to this at work. We had a policy about putting in for days off - anybody could put in for a day off and then the senior person would get it. The problem was that some sections of the policy said that you could put in for a day off “one month” in advance and other sections of the same policy said “thirty days” in advance. The policy was written in such a way as to imply the two terms were interchangeable - which of course they’re not.
So on December 1, people would submit requests to have January 1 off and the senior people would get the day off. Then on December 2, some more people would submit requests for January 1 and say that the day shouldn’t have been given off yet because today was thirty days before the date.
Wow, that’s confusing. Why aren’t you using a four-digit year, at least? I thought we’d already been through all that with Y2K.
In February, I got some supplements that had an expiry date of “02/07”, and I had to inquire of the company whether they meant “February 2007” or “2 July of the current year”. Turns out it was Feb. 2007, and they were shipping them really close to the expiry date.
(A four-digit year in year-first format–2007-03-02–would be unambiguous, but having only a four-digit year would make things clearer.)
Technically, the start of the first month after 2/29 is 3/1. So 1 month is from 3/1-3/31, 2 months -> 4/1- 4/30 … down to 2/(whatever the end of february is), is the end of the 12th month. 3/1 of the next year is the start of the 13th month.
If the AABB Tech Manual is indeed the proper reference material, I’m pretty sure you’re legally covered whatever you do (within reason obviously.) You just have to argue that the manual is vague as to exactly what time is needed to be indicated.
If you’re really that paranoid over getting sued, just make the expiration date 1 day before any of your choices and keep it around for a day just for emergency cases.
And then there are people foolish enough to put “daylights savings time” into their manuals. No regulatory agency knows what that is. I have heard of “Daylight Saving Time” which is official calendar event (speaking of which, the U.S. has a different Daylight Saving Time than the rest of the world so that has to be kept in mind) but there is no way to know if that related in any way to what you are talking about here.
It seems clear to me that if the “bible” says 12 months, then it’s 12 months.
If it had said 1 year then on Leap Years it would magically acquire another day of life.
Damn people, we going to end up with having to have disclaimers, warnings, and instructions on toilet paper!!!
