Apheresis Platelet Collections - Platelet Counts for Yield Calculation

[n.peters]

We are currently doing platelet counts on our full products as well as our spilts. How many places are just doing a platelet count on the full and using that number to calculate the splits yield with the volume? Thanks

[velliott]

When we do our initial count, to see what it qualifies for we just use the sample from the parent bag. Then we pull off for the bacterial detection, we use BacTech Alert, and then split. Then at the "storage" count we do volume, PH and platelet count. When we did our validation we did the parent and then counted the splits and then counted all again at "storage".

[goodchild]

I had been doing platelet yield testing for a number of years with the army with counts done on the full product and determining the yield for your splits with that number. It was maybe late 2007 or early 2008 when they decided to switch to testing the full product and if it was good enough for a split, individually testing each split for yield. I think it was our military inspecting agency who got us to start doing that (MEDCOM) and I think they said something or other about the FDA pushing for it, but I never really corroborated that with anything I saw/read - what MEDCOM wanted they got.

[Deb]

We only count the parent bag and then calculate for the splits. We validated the splitting process by testing each split from "X" number of collections and demonstrating the split yields were accurate whether calculated from the parent sample or individual sample. You just have be be sure your process for splitting the products is strictly adhered to. Letting too much time elapse while you wait for the products to equilibrate can result in an unequal distribution of platelets.

You can also apply for a variance to do away with the "end of storage" QC count/yield.

[heathervaught]

We do this, as well! We collect an EDTA tube at the time that we sample for BacT/ALERT testing, weigh the "main" bag, determine if it is eligible to be split (by weight), then equilibrate the product and weigh the potential "daughter" products. If at least one of the "daughter" products has a yield >3 x 10^11, we cut them apart and label them with the yield calculated using the "Main" bag concentration. We also have the variance that Deb mentioned -- we only test for pH at end of storage, but our FDA CSO required that we re-calculate the platelet yield using the weight after the pH sample is removed (2-5 grams).