Issues with Immucor Fetal Screen?

[yolis76]

We have had more than a few instances in which the fetal screen is obviously positive on a maternal post delivery sample (NOT weak D), but the KB is reported as completely negative. Has anyone else seen this? What could cause this? I have worked with this Fetal Screen kit for about 6 years and I have only seen this in the last 2 years or so.

[CPSHAN56]

Hello,

We have had the same issues within the last approx. 8 months. We switched to immucore when Ortho had their product issues a few years back. I do not remember having as many positive reaction as we have had lately.

[Mabel Adams]

I will tell a story if it could help someone else.

We used to wash our cell suspensions for fetalscreens (and for everything else for that matter). I would decant the washings by holding more than one patient's tubes in my hand--usually some prenatals I was doing along with the fetalscreen. On several occasions I got similar results to what you are finding.

I figured out that the other tube in my hand was always an Rh pos patient. When I flicked my wrist at the end of the decant, I must have splashed a miniscule amount of Rh pos cells into the fetascreen cell suspension. This was never enough to show up in any other kind of testing I did on it, but it did cause some rosettes to form. When I would repeat the fetalscreen on a new cell suspension, it would be neg.

This might not be your problem. What do you find when you repeat the same and new cell suspensions on your fetalscreens?

I have another theory since many of us use EDTA for ab screens now. Fact: reticulocytes will end up on the top layer if you spin a sample down in a capillary tube. Fetal blood is more likely to have retics (and bigger cells that are somewhat like retics), so if we don't do fetalscreens and Kleihauers on well-mixed samples, could we pull the fetal cells off first? We draw our fetalscreens in purple tops instead of the pink tops we use for gel testing just so we don't spin them down out of habit, then sample only from the top layer of cells when we make the suspension.

[babsglab]

I had both samples positive on my last CAP survey, one of them was supposed to be negative. The result did not count because so many people had the same positive result. I also use the Immucor Fetal Screen.

Babs in Maine

[Marcia Marchese]

We have also had a problem recently. I spoke with Immucor today. They are aware of the problem. They are looking at the indicator cells, the anti-D, etc. The next kit to be shipped will have a "different" anti-D so we will see if the problem is resolved.

Edited July 16, 2008 by Marcia Marchese
misspelling

[LCoronado]

We have also had false positives and I don't think it is likely to be due to contamination of the specimen. We also had an issue on the last CAP survey although I didn't make the connection with the kit until I read this thread. Prior to these recent developments we had no issues since making the switch from Ortho so I don't feel it behooves us to jump through hoops, or to change our collection requirements or our processes to accomodate something that is obviously a manufacturing issue. And, I called Immucor two days ago after finding four false positives in a week. I was told they have had 12-13 calls for the current lot number and also heard that the next lot will have a new Anti-D. Since we have no alternative to the Immucor Kit (other than performing a K-B on every postpartum patient) lets collectively pray for a speedy resolution to this problem!

[SANDRA CORBETT]

Call immucor Technical services. They will acknowledge the problem over the phone but not by written letter yet. They think it may be some problem with their detector cells in the kit. See the results of the last CAP survey, in which 2/3 of the participants got the Negative sample wrong. They found it positive with a neg KB. Unfortunately, Immucor seems to be the only vendor around, since Ortho pulled out due to their own problems with their Fetalscreen kit two years ago. We are now running in house KB testing with the Simmler stain kit on all positive Fetalscreens. We are taking Negatives, as the company does not see any problem with false negatives, only false positives. Sandy Corbett Blood Bank Manager Jordan Hospital

PLymouth, Mass.

[yolis76]

Thank you everyone for your replies! I don't think our washing technique is an issue, although it would make sense that if you manually wash an Rh pos with an Rh neg you could cross contaminate. We use cell washers for everything. I don't think the washer is the source of contamination either, because we have used 3 different ones, and tried washing manually, with the same results.

Again, thank you everyone for your insightful replies!

[krichards]

I spoke with Immucor about this today. We have had 5 false-positive fetal screens this month. (Our only other patient had a positive KB). Immucor stated that they have only had 20 calls regarding this problem, out of 4000 kits shipped. Just by reading this, though, it sounds like the problem is much larger than they realize/admit to.

The rep I spoke with suggested that some customers were having better luck when they washed their patient red cells prior to testing (which we do not do). The theory is that this will remove any RhIg in the plasma before it can bind to the anti D reagent. We're going to try this and see if it works.

[Ann Viernes]

Immucor's Fetal Screen is no longer the only kid on the block. Here's a link to another kit available in the US. It uses flow cytometry. This is not an endorsement, I just received fax information and when I read about the problems, thought I'd pass this on to those of you with access to flow. http://www.albabioscience.co.uk/Quant-RhoFAQ.aspx

[ffriesen]

We have also seen false positives in the last month. I'm so glad to know they are acknowledging the problem now. I called them back in March because we saw an in increase in false positives and they investigated and told me there couldn't find any problems. I will give them a call today and log another complaint!

[Mer]

We haven't had a problem with the Fetal Screen Kit, but we have had a problem with Ortho Panel Cells...we switch our main gel panel cells once a week (large hospital/many panels) and at the beginning of the week we noticed that all our patients had a 1+ on cells 4 & 6...we usually then go to a separate Peg panel and everything turned up negative for id'ing those positives...we called Ortho, but they weren't able to provide us with another full panel set until the next week.