Jump to content

Echo Issue


ackkap

Recommended Posts

We are in the process of validating our new ECHO.  Our current method is manual Ortho Gel.  We have a 28 week pregnant O negative female with a 4+ antibody screen in gel.  Her antibody was identified as Anti-D (4+ reaction strength) in Gel and titered out to 8 at 37 degrees and 8 at IgG using Immucor screening cells in tube testing.  My question/problem is when we ran it on the ECHO, the screen and all panels available to us were negative.  I've seen many posts where the ECHO is too sensitive an instrument, but no posts where a 4+ antibody in Gel produced a negative reaction in Solid Phase (ECHO).  Has anyone had similiar results or an explanation why the ECHO results are not coming up?   According to the patient and the hospital she transfered from, she has not received Rhogam and had a negative antibody screen at the start of this pregnancy. 

Link to comment
Share on other sites

We also usually have the "more sensitive" issue with the Echo versus the backup tube method but coincidentally, we just had a problem with API proficiency testing samples where the Echo results were negative or equivocal, when repeated where the same or maybe 1+. .  The tech doing the PT exercise instinctively decided to check the results against the tube and got very strong positives for the Anti -D samples. I alerted Immucor about this because the last survey had a similar problem. They asked me if the samples in question were possibly weak D's but we don't check for weak D except on cord bloods so I didn't run any weak Ds.

Link to comment
Share on other sites

I also called Immucor to report my findings and they asked me about the possible weak D as well.  We did run the weak-D and it was negative.  I'm starting to have doubts about my ECHO especially if its missing 4+ Anti-D's!  Has anyone else had this same issue??

Link to comment
Share on other sites

My sister hospital also uses API for their surveys and has had the same problems with their Anti-Ds.  The new Policy is to replace the reagents after two weeks.  They have also instituted a policy to test all new D negative patients/samples on the bench.  They are using the exact same reagents on the bench and getting the expected reactivity, while on the Echo it was negative...weird

Link to comment
Share on other sites

This is not happy news. I don't want to go tossing reagents after two weeks especially when we use the same Series 4 Anti-D in tube and on the Echo and daily QC always  is very acceptable with both methods. If its something to do with the Echo CMT plates, well I sure as heck don't want to go tossing those every two weeks- the expense would be ridiculous. Weird is a great word and what bothers me is that after blaming the API samples or the patient samples, eventually we will receive some kind of bulletin from Immucor about this problem??? I do like working with them and find them very responsive but it is always, always "a problem with your samples". I don't buy it.

Link to comment
Share on other sites

I may be confused but it sounds like we are talking 2 different scenarios.

If I am reading the original post correctly the poster is concerned about an POS Antibody Screen ID'd as Anti-D (titered to 8) identified in Gel but when performed on Echo the Antibody Screen is NEG.

Later posts seem to be referring to Rh typing of patients with Anti-D4 and D5 missing Rh+ patients, typing them as Rh-.

 

We have been running with Echos for about 18 months (before that we had a Galileo) and I have not see this similar scenario. Like the first response, we tend to see the opposite, ABSC Pos on Echo and not by backup. We used to use Gel as our backup method and we did have some antibodies identified by Echo that were negative in Gel. Usually these were Anti-Kidds or Duffys. I don't think I've ever seen a discrepancy with an Anti-D.

 

How long between the pos results in Gel and the neg result on Echo. Was this a fresh sample or an old sample that had been saved for performing validation? If it was saved, how long and was it frozen?

 

I'm sure all of the usual clerical errors were excluded i.e. the same specimen was used for both the Gel and Echo testing. For Gel, there were no identification errors between specimen and gel card.

 

Was the Echo Antibody Screen performed using the primary specimen or was an aliquot removed an run on he instrument. If it was a specimen that was saved for validation, there was not a labeling error. When it was performed on the Echo there were no bubbles at the top of the specimen causing it to pipet incorrectly (when we first started running our Echos the techs had a couple of times where they forgot to check and then came up with unexpected results) .

 

Also, does the patient history indicate any trauma or procedure that could have resulted in bleeding. Is it possible she received RhIg-D and doesn't equate that to "Rhogam"? I had a patient in the not too distant past with Anti-D identified in her plasma at 28 wks who was asked if she had "received Rhogam"  and stated no. Upon further investigation we found out she had fallen a month or so earlier and received RhIg-D (Rhophylac) in the ED at another facility but either didn't remember (not sure if she didn't get the card or lost it) or did not equate that to Rhogam. This doesn't explain the negative on the Echo but might explain the positive in gel with no history.

Link to comment
Share on other sites

We have seen Anti-D being ruled out when there is also an Anti-E or Anti-C present. We now test Rh neg patients by Gel if they are shown to have Anti-E or Anti-C by Echo. But usually our Anti-Ds show up ok on Echo.As for the weak reactivity vs Anti-D reagent on Echo, we do see a 1+ or 2+ lower reactivity of the Anti-D vs tube. At one point, we had even weaker reactivity on one of our Echos with the Anti-D reagent (we have 2 of them) and Immucor replaced the camera and reactivity increased. I also know "tweaking" the belt on the strip carrier arm can also change reactivity

Link to comment
Share on other sites

Jalomache - to answer your questions, the samples were run the same day fresh, not frozen, from the primary tube, using manual Gel and then immediately placed on the ECHO.  We drained the sample and asked for a redraw and saw the exact same results (4+ D in Gel; Negative Screen, Negative ID on the ECHO).  No clerical errors and according to the transfer hospital and the patient, she had not received Rhogam.  I agree with you, though, you can't always believe the patient!  Immucor was telling me it may have been a newly developing IgM Anti-D so gel would find it, but not the ECHO because according to their literature, ECHO's only pick up IgG antibodies.  I'm not sure I believe that response.

Link to comment
Share on other sites

We have seen Anti-D being ruled out when there is also an Anti-E or Anti-C present. We now test Rh neg patients by Gel if they are shown to have Anti-E or Anti-C by Echo.

 

Wow!  All of your Rh Neg Anti-E and Anti-C's need additional testing in Gel to rule out an Anti-D.  It seems like the ECHO has a history of missing Anti-D's yet nothing has been done by Immucor about it.

Link to comment
Share on other sites

I  disagree as well that it is not picking it up b/c its IgM. If it  titers out to 1:8 in tube with IgG-I would absolutely expect it to be picked up by a system that is purported to be more sensitive then tube.  Hopefully you get another redraw in 3-4 weeks (or pt. delivers at your facility) so you can follow the titer and reactivity.

Link to comment
Share on other sites

Folks,

 

You are forgetting a few points about anti-D and dealing with it in the IgM form or as RhIg.

 

1. A product called Saline anti-D (and saline versions of -C, -E and -c) was manufactured 40 years ago from donors who made only IgM anti-D and never converted to IgG. As soon as chemically-modified reagents were available for DAT positive samples, the saline product came off the market. The donors were dying of old age (and not easily replaced) and the cost of the reagent was sky high.

 

2. If the titer at 37C was 8 and then again at IAT, the titer was still 8, there is no additional IgG activity. The binding seen at 37C is most likely due to the IgM and it is not un-binding through the wash process. If there was more antibody bound that could only react when anti-IgG is added, the titer would most likely go up. If the 37C and IAT testing was run in parallel sets of tubes, all you saw at IAT was the IgM causing direct agglutination.

 

3. Antibodies with a preference for colder temps or those with a low binding co-efficient will probably not stay bound through the washing process. Those are the only IgM antibodies likely to show a higher titer at 37C and a lower titer at IAT. Most examples of anti-D have very good binding co-efficients which is why they can do so much damage in circulation.

 

4. RhIg, while being an excellent protective measure for D negative women, is just an artifact in pre-transfusion testing. The patient will always be given D negative products anyway!  The biggest issue with RhIg, is that while being manufactured from large pools of plasma with all sorts of RBC antibodies, the final product is also a little different depending on individual manufacturer's recipe. The delivery can be IM or IV and that impacts how much and when it will impact the patient's circulation. Given the sensitivity of Capture, it only makes sense that the manufacturer would acknowledge the impossibility of detecting this artificial antibody 100% of the time. Missing it would almost be preferred as it adds no relevant information for crossmatch testing or the fetus. We would like to see the real alloantibodies that could attack any D negative component transfused in our pre-transfusion testing.

 

That all said, I do believe the manufacturer should support their product and be given a chance to investigate this sample to see how or why their products are not reacting as expected. It would be very educational for all of us to hear the outcome of the investigation. Since the FDA inspects all of our manufacturers' customer complaints and product investigations this has to be performed according to SOP, just like any other blood bank procedure. We can't be given a Marketing spiel.

Link to comment
Share on other sites

Pony - Thanks for your comments.  I think they are right on.   We have sent Immucor a sample yesterday so I will let you know of their findings.  Our patient delivered yesterday and the baby had a negative DAT and negative antibody screen, so I do believe our patient only made IgM Anti-D.  Immucor all along was telling me it must be IgM because the ECHO didn't pick it up and I didn't believe.  I just couldn't get past a 4+ positive Ortho Gel result that yielded a negative ECHO result.  I believe now!

Link to comment
Share on other sites

ackkap - Thanks so much for the follow up! I'm so glad to hear the baby is safe. I haven't seen a case like yours in years so it would be very worthwhile to write it up as a case study. ARC's Immunohematology journal would be a good spot to place it. They still publish practical topics for us serologists.

 

Even better, following this woman could be really interesting. Any chance she might get pregnant again? Technically she isn't a candidate for RhIg but in practical terms - might it prevent her converting to IgG? A shot won't hurt her or the baby. Afterall we give it to D+ ITP patients to help boost their platelet count using the competitive binding theory.

 

You will have to keep an eye out to see if this delivery prompts her to convert to IgG. I've never seen one of these past a single pregnancy. Best of Luck!!

Link to comment
Share on other sites

We have seen this phenomenon also, usually with early anti-E that is still IgM.  We have seen several OB patients with 4+gel  anti-E that, in tube testing, may be picked up at 37C reading and may be negative or at best wealy positive at the antiglobulin phase.  These usually seem to progress to IgG as the pregnacy progresses.  

Link to comment
Share on other sites

I have a different issue with the Echos and NEO. Since we went live with the Echos and NEO in April, we have had MANY pregnant Rh pos females that react (3+ to 4+) with ALL 3 screen cells, ALL ready ID panel cells, and ALL extend panel cells, DAT is neg.

When we perform the antibody screen by gel card, all cells are neg.

I asked Immucor Germany about these patients, and they stated that pregnant females will react like that after receiving Rhogam.

BUT these patients are Rh pos, and the Rh neg patients that have received Rhogam show only the anti-D reaction.

Does anybody else have this?

Link to comment
Share on other sites

Yes we have had the same issue exactly as you are describing.  There was mention that it might be a latex allergy in the patient reacting with solid phase system.  

 

Another time they said it was the Capture R-RS lot of strips that were nearing expiration.  Upon using the new lot, the patient antibody screens were negative.

Link to comment
Share on other sites

We see this from time to time with Prenatal panels. If the PeG antibody screen is negative w/ a negative auto, we report the antibody screen as negative. We also included a note in the patient's record - solid phase reactive antibody of no apparent specificity and that PeG (or LISS) was used to resolve.

Link to comment
Share on other sites

Thank you, I am so glad I am not alone. Immucor and the vendor here are not very helpful. I also comment in the patient's file to test with gel card if required. (Will go back to PeG when I can get the vendor to deliver minor things like PeG, screen cells,anti-IgG, coombs control cells!)

Sorry! It has been a hard month here!

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Advertisement

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.