Quick! Run the controls on this new lot V116323 of Fetalscreen II to make sure they work before the old lot expires tomorrow. We can't get the pos control to be positive and we checked it several times. We ran the pos control from the old kit with the new kit and the old control is more positive although a bit weaker than it was with its own kit. Ortho says they have no other lot to send as a replacment and they are getting quite a few calls on this lot. They will credit it. Yes, we spun the tubes for the 45 seconds.

I suspect it is the control not the kit. Anyone know how to make your own controls for rosette testing?!? Argh!

Mabel,

I just pulled Judd's Methods off the shelf and following is the information I was able to find:

Positive control RBCs:0.6% RH+ RBCs in RH- RBCs, prepared by mixing 1 drop of 3% Rh+ RBCs with 16 drops 3% Rh- RBC's and diluting 1 drop of this mixture with a further 9 drops 3% Rh- RBCs.

Hope this helps!!

Well, that is the same make-up as Ortho's pos control so we tested it and it works with the new kit. Now to try to nail down suffiently for inspectors and good medicine that this failure is due to the control not the kit and get Medical Director to approve emergency use of a homemade control and just maybe we can get by. Accepting all opinions on how to document sufficiently or whether this is a crazy idea.

Do you have any Pos proficiency test material that you can use?

Did you run the new positive control with the outdating kit? If the kit was Qc'd as working correctly using the Kit's positive control then the positive control from the new kit could be tested as an "unknown" if you will to see if it is showing as positive. If not, I would say you determined the issue by using two diferent lots of reagent with the "offending" control. As for the medical director, remember that purchasing a kit is not mandatory, just convienent. If you can show the proper response of the homemade control with the kit and explain the limitations of no other lot number available, perhaps the medical director would be in agreement. Let us know how this goes. Oh, and for the record the idea is not crazy. Being creative within the guidelines is expected when in a jam !

Edited December 13, 201113 yr by Deny Morlino

Thanks for the alert! We ran controls and the rosettes were weak to non-existent. We always run the old controls with the new kit but not the other way around.

Mabel,

I just pulled Judd's Methods off the shelf and following is the information I was able to find:

Positive control RBCs:0.6% RH+ RBCs in RH- RBCs, prepared by mixing 1 drop of 3% Rh+ RBCs with 16 drops 3% Rh- RBC's and diluting 1 drop of this mixture with a further 9 drops 3% Rh- RBCs.

Hope this helps!!

So, how long would this homemade control be good for? Would you make them fresh at each use or assign an expiration date? Thanks.

I talked to our reference lab about how long they rare store cells they thaw out for antibody testing and she said they sometimes last a week, but to observe for discoloration or contamination. I am saying a week or until there are signs of deterioration, but the recipe only makes 10 drops so it may not last that long which I think is fine. I'd rather make it up every few days than have it get "icky." The recipe above starts with washed 3% suspensions of Rh- & Rh+ cells. It says the same recipe in the Tech Manual.

Quick! Run the controls on this new lot V116323 of Fetalscreen II to make sure they work before the old lot expires tomorrow. We can't get the pos control to be positive and we checked it several times. We ran the pos control from the old kit with the new kit and the old control is more positive although a bit weaker than it was with its own kit. Ortho says they have no other lot to send as a replacment and they are getting quite a few calls on this lot. They will credit it. Yes, we spun the tubes for the 45 seconds.

I suspect it is the control not the kit. Anyone know how to make your own controls for rosette testing?!? Argh!

Ran controls from this kit today. The positive control for us gave a positive result.

Does anyone know why the various rosette kits seemed to be fine the first 20 years they were on the market, but have had nothing but trouble the last 10 years? Maybe that is when they started requiring proficiency testing so we found the problem? We have a weak control again on Lot V108381. We will repeat to make sure it is not us.

Does anyone know why the various rosette kits seemed to be fine the first 20 years they were on the market, but have had nothing but trouble the last 10 years? Maybe that is when they started requiring proficiency testing so we found the problem? We have a weak control again on Lot V108381. We will repeat to make sure it is not us.

Confession time!!!

The reason this last lot did not work is that it expired in May of 2011! This is not a problem of Ortho's and I regret having created a bad name for them on this site. Amazingly those year old cells are not lysed. How this came to happen is a classic story of error where one unusual situation led to a mistake by a person that seldom works the shift she was working which led to another mistake and a misinterpretation etc. etc. etc.

The new Ortho Fetal Screen kit arrived today and it works fine.

Mabel, I completely understand.

Mabel, I think the technical term for that is "Whoops!!!"

Donna