Good Morning Everyone! New member here 

I have a silly question. I've been a tech for 9 years, and still debate this with myself all the time. When you are interpreting a screen or panel using MTS cards, at what point do you call a "weak" reaction a positive or negative? I've looked through the interpretation guide provided but I still struggle with this sometimes. Occasionally you will have a cell that appears mostly negative, but has a few small agglutinates, much less than what the images in the guide calls "weak" (Usually gives a ? if using the Provue). I wish I had a photo of what type of reaction I am talking about, but I'm sure those using ID-MTS know what I'm talking about 

 

Thanks!

SweetieShellie,

I guess I understand what you mean. Whenever I have such reaction in my gel cards, I look for other factors before I call it positive or negative. Firstly, I look for my negative controls, which will give me an idea of negative reaction. I also look for patient diagnosis, pregnancy hx, transfusion hx or any thing that has potential to cause positive reaction. I am very conservative about grading my reaction.

 

I have this issue also. The guide doesn't give a weak reaction as a result. I always go by if it's a pellet with a few "specks" it's negative....why search for zebras.

Similar practice here.  There are thinbgs that can cause gel interference that look like they may be junk, including a dried speck of 0.8% cells that hangs above and otherwise negative bunch of cells at the bottom of the tube.  

However, if it is an artifact, somehow it must be proven to be only that.  If it is due to the gel, then we do a tube screen to see if we can get a clean negative.  Likewise, for really weak gel screening reactions (Ortho says to report as 1+), we may do a panel to make sure there is no pattern that would match an emerging alloantibody (a young zebra--but still important!).

Scott

On ‎3‎/‎7‎/‎2017 at 9:02 AM, SweetieShellie said:

Good Morning Everyone! New member here 

I have a silly question. I've been a tech for 9 years, and still debate this with myself all the time. When you are interpreting a screen or panel using MTS cards, at what point do you call a "weak" reaction a positive or negative? I've looked through the interpretation guide provided but I still struggle with this sometimes. Occasionally you will have a cell that appears mostly negative, but has a few small agglutinates, much less than what the images in the guide calls "weak" (Usually gives a ? if using the Provue). I wish I had a photo of what type of reaction I am talking about, but I'm sure those using ID-MTS know what I'm talking about 

 

Thanks!

I think that after you use them for a long time.....running panels and seeing which "positive" reactions pan out to be something, and which do not; you start to get an "eye" for what is a true positive vs. a few red dots that are not going to give you anything (or, you learn the "look" of a cold agglutinin; rouleaux; warm auto; vs. clinically significant antibodies).  I think it just takes time and experience (going after the questionable reactions long enough to know "when" to go after them)  to feel comfortable (and in the end, you could still be wrong; but there is also a good chance that if it is so weak that you can't decide whether to call it Positive or not, you probably won't find anything anyway).  Just my opinion.

Brenda Hutson, MT(ASCP)SBB

We centrifuge the plasma again and repeat testing with a 30 minute incubation time.  For most samples, this seems to clarify things one way or another.