O neg 70 y/o , M trauma case. Antibody screen neg.

Crossmatched 12 O pos PRBCs , all showing 1+ to 2+ in gel

Then cross matched O neg units, compatible.

What could be the reason? Why did the antibody screen not show up any thing?

We are using Bio rad antibody screening panels

Did you do an abid? . . . result?

Positive DAT?? What, if any, additional testing have you done?

:coffeecup

Why were you doing gel crossmatches if the antibody screen was neg? Was there antibody history? Did you run a panel? Did you try other enhancement media such as PEG?

Was there any pathological condition, underlying the major trauma? Like John, I am wondering about a weak positive DAT, with an antibody that may be mimicking an anti-D, such as a weak auto-anti-LW.

Edited June 19, 201213 yr by Malcolm Needs
Couldn't spell John!!!!!!!!!!!!!

You said crossmatches were done in gel. What method did you use for your antibody screen?

You said crossmatches were done in gel. What method did you use for your antibody screen?

Good point - I hadn't noticed that bit - or ignored it - one of the two!!!!!!!!!!

Good point - I hadn't noticed that bit - or ignored it - one of the two!!!!!!!!!!

I hear you....I have been guilty of that myself.

We'll get to the bottom of this once we have all the information.

Positive Cxms and neg AbSc reasons:

1. low incidence antigen on donor cells.

2. Donors are (all) DAT positive

3. Homozygous expression on donor cells and hetero on screening cells for a given Ag

4. Delay between Cxm pos and neg, the interfereing "stuff" settled.

5. AbSc done in tube while gel Cxms more sensitive

6. Patient is weak D with a weak anti-D

7. Patient has excess proteins causing pos result in gel, these are washed away in the tube method.

8. Patient has antibodies against stuff in gel (cxm).

>>> more??

I shall await your reply to the questions about what you did asked by the posters.

I have my doubts about 1 and 2 Liz!

I agree, I was considering if just one crossmatch was positive

Just out of my own curiousity, it looks like everyone else has this covered, when you say crossmatches were performed in gel: did you mean a simple buffered gel card to mimic immediate-spin technique or an IgG gel card? If IgG, why were you doing extended crossmatches on a person with (presumably) no history of antibodies, especially since it was a massive trauma?

O neg 70 y/o , M trauma case. Antibody screen neg.

Crossmatched 12 O pos PRBCs , all showing 1+ to 2+ in gel

Then cross matched O neg units, compatible. What could be the reason? Why did the antibody screen not show up any thing? We are using Bio rad antibody screening panels

Read all responses previous to mine before replying, but I am wondering why not the obvious: Patient is Oneg. Antibody Screen Negative. You wanted to give him Positive units. Perhaps he had a previous exposure and had a weak Anti D? So crossmatches were positive? Like everyone else wonder if ABS done on tube instead of gel (less sensitive). Regardless I think its an Anti D.

Verify with enhanced ABS and ABID... But that would be my first thought. That and maybe Biorad D cells not strong? (Unlikely).

Read all responses previous to mine before replying, but I am wondering why not the obvious: Patient is Oneg. Antibody Screen Negative. You wanted to give him Positive units. Perhaps he had a previous exposure and had a weak Anti D? So crossmatches were positive? Like everyone else wonder if ABS done on tube instead of gel (less sensitive). Regardless I think its an Anti D.

Verify with enhanced ABS and ABID... But that would be my first thought. That and maybe Biorad D cells not strong? (Unlikely).

Good point Barbarakym! Seems like we blood bankers like to overlook the obvious.

Agreed, but I am sure Liz was just being thorough!

I have my doubts about 1 and 2 Liz!

1. As others questioned, why perform GEL Crossmatches with Negative Screen?

2. 70 yr old Rh NEG woman; would not be "uncommon" for her to have Anti-D, Anti-C and

possibly Anti-E if she has ever been pregnant (pre-Rhogam days).

3. Scenario 1 place I worked: Patient with history of "unidentified;" which usually translated to

"possible Low Incidence." But not sure; the initial work-up was performed before I started

working there. So, fast forward many years...due to history, AHG Crossmatches were

performed (but current Antibody Screen in GEL was Negative). Tech. came to me saying 2

of 3 crossmatches were incompatible. Obviously, this would not "make sense" if possible Low

Incidence. So, had him perform a Panel. GEL Panel showed a clear-cut Anti-Fyb. Why??

Not sure why Negative Antibody Screen (repeat Negative); but have heard of problems with

Fyb and Jka in GEL (have seen it a LOT with Jka).

Brenda Hutson, CLS(ASCP)SBB

My first thought is, nothing was dripped into the screen. I don't know if you repeated the testing to check that, but it sounds like a good candidate for an anti-D, so I would probably check that the screen had serum/plasma in it.

O neg 70 y/o , M trauma case. Antibody screen neg.

Crossmatched 12 O pos PRBCs , all showing 1+ to 2+ in gel

Then cross matched O neg units, compatible.

What could be the reason? Why did the antibody screen not show up any thing?

We are using Bio rad antibody screening panels

What I also see is that they are using BioRad, which is Tube, but they are doing gel crossmatched.... do the ABS is Gel, but then this message is over a month old so they should have already gotten their answer.... I bet an antiD missed in the tube antibody screen.

My first thought is, nothing was dripped into the screen. I don't know if you repeated the testing to check that, but it sounds like a good candidate for an anti-D, so I would probably check that the screen had serum/plasma in it.

Another good basic point. Look for a horse in a herd of horses before you look for a zebra. Though finding zebras are much more interesting, I agree.

Bio-Rad in Europe (and other parts of the world, I assume) is essentially the same gel as Ortho's MTS gel in the US. Bio-Rad will be marketing it in the US end of 2013 or early 2014.