cbaldwin

The following is an abstract that was presented at the October 2013 AABB meeting in Denver.  I thought it was interesting and remembered this subject had been discussed here, so I dug up this thread and am posting this....
 
SP219 Detection of ABO Incompatibility in the Extended IgG Gel CrossmatchR M Barrett1,2(Rachelle.Barrett@salemhospital.org), T Kasper1. 1Blood Bank, Salem Health Laboratory, Salem, OR, United States; 2SBB Program, University of Texas Medical Branch, Galveston, TX, United States
Background/Case Studies: AABB Standard 5.15.1 states: “The crossmatch shall use methods that demonstrate ABO incompatibility and clinically significant antibodies to red cell antigens and shall include an antiglobulin test.” When a clinically significant antibody other than ABO is detected during pretransfusion testing, the crossmatch is performed using the same method used in detection. Many extended crossmatch methods do not have an immediate spin reaction. The testing facility for this study uses MTS IgG Gel cards for detection of clinically significant antibodies other than ABO in extended crossmatch. To meet this standard, an immediate spin crossmatch is required in addition to this extended crossmatch. If it could be proven ABO incompatibility is detectable even by methods not designed for such purposes, the extra step of completing an immediate spin crossmatch in the case of the extended crossmatch could be eliminated for the sake of efficiency. Study Design/Methods: Twenty randomly selected samples of each ABO blood type were crossmatched with known ABO incompatible donors at tube immediate spin and on MTS IgG gel cards. Known ABO compatible crossmatch donors were used as controls. Randomly selected samples were also tested for complement activity using commercial anti-c3b-c3d in tube. Results/Findings: ABO incompatible crossmatch was apparent 100% of the time at immediate spin for all samples tested. Type O and A samples demonstrated incompatibility in 100% of samples tested on MTS IgG gel. Type B samples gave negative reactions on IgG gel in 15% of samples tested. Furthermore, type B samples had significantly lower grade reactions on gel as compared with Type O and A samples. Samples that were negative on gel were also negative for complement activity. Positive gel reactions correlated with positive complement in the few samples tested. Conclusion: The clinical significance of the ABO antibodies made by the % of patients testing negative in gel is questionable. If the ability to fix complement is diminished for these antibodies, are these patients then protected from hemolytic transfusion reactions when exposed to type incompatible blood? Until further study determines the clinical significance of these differences in antibody activity, this study suggests completing an immediate spin crossmatch in addition to extended crossmatch methods when extended crossmatch testing methods do not already include an immediate spin reaction.
Disclosure of Commercial Conflict of Interest
R. M. Barrett: Nothing to disclose; T. Kasper: Nothing to disclose
Disclosure of Grants Conflict of Interest
R. M. Barrett: Nothing to disclose; T. Kasper: Nothing to disclose

4.  Or possibly another antibody that reacts with the expected screening cells, but is a different specificity, that is not detected in the IAT cross-match because, unlike the screening cells, which are in a preservative that is designed to "keep antigenicity", but not "oxygen carrying capacity", the unit's red cells are kept in a preservative that is designed to "keep oxygen carrying capacity", but not "antigenicity", and, in any case, may only have heterozygous expression of an antigen, whilst the screening cells have homozygous expression of an antigen.  Why take the risk with a patient's life, and your own future in the profession?

Yes we go by our package insert as well which states at least an hour after delivery but soon after, so we told nursing to draw them 1-3 hours after delivery.
If you wait until the following day the fetal cells could already be cleared out of the mom's circulation and you would get a false negative.

I believe many eons ago the package insert for some of the fetal screen tests referenced the one hour time period but I do not have access to those to confirm.  I believe the rationale was/is that if the fetal cells are ABO incompatible with the mother, the fetal cells will be destroyed by the maternal antibodies so a falsely low value of the amount of fetal bleed may be obtained.  I know everyone here understands that ABO incompatible fetal cells actually provide some natural prophylaxis to the mother for the prevention of immunization to D so may be less of an issue if you're doing the test simply to determine RhIgG dosing.  The same rationale could apply for early removal of D-positive fetal cells from the maternal circulation due to the presence of any prophylactic/antenatal anti-D.  However if the test is being performed to determine the amount of fetal bleed as a diagnosis test for the treatment of the infant, one should be aware of these factors that may affect the result.     

I am going to be REALLY unpopular here, but I'm going to say it anyway (because I am a pedant)!!!!!!!!!!!
 
Antigens CANNOT be either heterozygous or homozygous; only genes can be heterozygous or homozygous.
 
An antigen can be described as either showing homozygous expression, or heterozygous expression.
 
That having been said, is a red cell sample that types as K+k- phenotypically, genotypically K/K or K/Ko, or even K/k, with a mutation within the Kell gene that prevents the k antigen being expressed and detected with all anti-k grouping reagents (just in case anyone doesn't believe me - we had one!).
 
That's got that off my chest.
 
Now then, there is NO doubt that there are some anti-K's around that only react with K+k- red cells (dosage), but they are fairly rare, however, how many people use antibody screening red cells that are K+k-?  I doubt if there are any.  Therefore, we are all ruling out anti-K using red cells with apparent K antigen heterozygous expression on every single sample that (apparently) has no atypical alloantibodies present.  Am I wrong about this?
 
It follows, therefore, that, over the years, there MUST have been occasions when a patient with a very weak anti-K (one that is only detected using red cells that are apparently showing homozygous expression) and who has been transfused with K+ blood (do the maths).  As far as I know, there are no papers within the literature that report a case of either a delayed or an acute transfusion reaction as a result of this.  Yes, this may cause the anti-K to become stronger (and, hence, be detectable using an apparent heterozygous red cell sample showing K+k+ expression), but then, if this happens, you give K- blood.
 
So, my considered answer is that you can exclude using K+k+ red cells.
 
I shall now go and lie down!!!!!!!!!!!!!

I'm also getting ready to test out the ShockWatch TrekView gadget  - to monitor internal temperature of the cooler - they are less than $50 each.  Can be used up to 26 times.  They are cute, too!

We recently purchased a ScanTemp 485 temp gun.  Have been very pleased.  Validated it against our NIST thermometer.  Of course, now we are discarding more products
 .

What brand is the infrared gun thermometer, who was the supplier and how much did it cost?
 
Catherine

Unfortunately we do perform an absc for RhIg.  I have one OB guy who wants it done and one who does not.  I don't have different rules for differnt docs - I have tried having my MedDir talk the one out of this but all he says is "What if they have anti-D?"  WELL MOST OF THEM DO NOW because we use gel.  Does he do a recheck in 3-4 months as suggested - NO!
 
enough said.

Thank you for your kind comment David.
 
Anti-M is the bane of my life!
 
Until relatively recently, if an anti-M was referred to my laboratory, we would test it first by Bio-Rad (Used to be Dia-Med) gel IAT and enzyme technique (enzyme technique to see if anything else is there - even I know that the M antigen is destroyed by papain!!!!!!!!!) to make sure that there was an anti-M present.  If there was an anti-M present, we would then test it by pre-warmed, warm-washed LISS tube IAT at 37oC.  If we saw no reactions by this technique, we would advise that cross-match compatible blood would be suitable, and safe, for transfusion.  If we did see reactions by this technique, we would advise that M- typed blood should be cross-matched, and those compatible transfused.
 
The reason for the difference between the gel technique and the tube technique is two-fold.
 
Firstly, in the gel technique, the reactants (plasma and red cells) are introduced to each other at room temperature, and then the cassettes are put into a 37oC incubator.  "Cold-reactive" antibodies can sensitise red cells in "peco-seconds" (I may have exaggerated a bit there!!!!!!!!!!!), but the antibody-antigen complex takes a bit of time to dissociate (longer than the incubation time), and so a "false IAT positive reaction" is seen.  On the other hand, if the reactants are introduced to each other, already at 37oC, "cold-reacting" anti-M will (eventually) sensitise red cells, but not in the time allowed for incubation, and so the reaction would be negative.
 
The second reason is that the column containing the AHG is slightly acidic, and if there is one antibody/antigen reaction that likes acidic reactions, it is that between anti-M and the M antigen.
 
I was quite happy with this situation, BUT, and my own line manager is well aware of this, so I don't mind saying it publically, NHSBT has decided, on the grounds that most of our hospitals use gel techniques, we now recommend giving M- typed blood to anyone who has an anti-M, which I think is a total waste of units of blood that have been typed for all sorts of other antigens and have been found to have (presumed) homozygous expression for other, more useful, antigens.
 
I am well aware of the fact that anti-M can cause haemolytic transfusion reactions (IF serologically reactive at 37oC) and can cause clinically significant haemolytic disease of the foetus and newborn (IF serologically reactive at 37oC), and, in the case of HDFN, particularly amongst ethnicities in the Far East, such as the Japanese, irrespective of titre, but these cases are very, very rare.

We only do weak D on babies and donors. However, I have some pts (including 3 where I work) whose D typing in gel is marginally positive, tube testing D on these women is vw+ in all phases tested. They are A+ blood donors. 2 of them were OB pts and I told the docs we were going to give them RhIg and treat them like they were Rh=. Of interest is that I had the Quotient D typing panel. All three women had the same reactions with that panel, yet they aver they are unrelated. Interesting but of no clinical signficance as for as a Transfusion service goes.
I also think that one must interpret vw gel D rxs with caution. There are many and varied comments on how to interpret anti-D rxs <4+ in gel. One has to find a comfort level but be prepared to step out of the box for these margnal rxs.

There is an article on page 650 of the March 2014 Transfusion journal about a 14-year retrospective study at Beth Israel Deaconess Medical Center, Boston Massachusetts that looks at the anti-D alloimmunization rate in D negative patients who received D positive platelets.
 
The article is interesting because it points out the low alloimmunization rate in these patients.  For those of you without easy access to this journal, I will summarize:
 
The article reminds us that most (85%) platelet units transfused in the US are apheresis platelets, and apheresis units contain less than 0.001 mL RBCs, whereas platelet units from WB typically “contain a few tenths of a milliliter of RBCs”.  There is less exposure to the Rh antigen in apheresis platelets.
 
In the study, of 130 D negative patients that received prestorage LR apheresis D positive platelets, none formed anti-D “as shown by negative antibody screens at least 4 weeks after the incipient transfusion.” The patients were 52% male and 48% female.   43% were immunosuppressed and 57% were immunocompetent. 
 
The study started with 626 patients but many had to be eliminated because didn’t conform to the study’s requirements.
 
Of those patients that were eliminated,  354 patients were eliminated  because an antibody screen was not performed greater than 4 weeks after transfusion.  The antibody screen may not have been done because of death, discharge home, etc.  The authors state that this population that was eliminated may have made a difference in the outcome of the study if an antibody screen had been done greater than 4 weeks after transfusion and the population included.
 
However, their conclusion is that the findings “support the use of D+ apheresis PLTs irrespective of Rh status, D+ or D-, in all patient populations without the need for RhIG immunophophylaxis.
 
I think this is interesting and so decided to make a post….

Well,
 
There was a total of 626 D negative patients at the start....
 
23 were excluded because they all ready had made anti-D
 
50 were excluded because they received D+ RBCs as well as platelets
 
45 were excluded because they received RhIG
 
16 were excluded because they were allogeneic HSCT patients who had D+ donors
 
354 were excluded because an antibody screen was not performed >4 weeks after transfusion (the range for the ab screen was 4-464 weeks with a mean of 76 weeks)
 
....so that left 130 patients in the study.  I am pretty sure from reading the paper that the immunocompetent patients did not receive prophylatic anti-D.
 
The authors  state:  "We sought to retrospectively determine the rate of anti-D alloimmunization after D-incompatible apheresis PLT transfusions in those patients who did not receive RhIG or D-incompatible RBC transfusions between 1/1/1997 and 12/31/2011.

Hi Mabel,
 
IgA can activate complement via the properdin or alternative complement pathway.  JoAnn Moulds reminded us of this at the "Who DAT" session at the 2013 AABB meeting in Denver last October. 
 
At this session Patricia Arndt spoke about negative DATs in patients with clinical hemolysis.  Patricia Arndt mentioned more sensitive methods that can demonstrate antibody on RBCs in these patients.  These methods include cold LISS wash DAT method, flow cytometry, direct Polybrene test, also testing with anti-IgA and anti-IgM reagents.  Anti-IgA and anti-IgM reagents are not commercially available in the US, but Pat's lab has these reagents for research and special cases. 
 
But Pat also mentioned that anti-IgG reagents that are not heavy-chain specific can pick up IgA and IgM because these reagents may have antibodies to kappa and lambda light chains and can react with IgA and IgM light chains.
 
Pat presented a case of a 5 year old with clinical hemolysis (Hgb = 6.4, bilirubin high, LDH high, etc) and a negative DAT.  It turned out this 5 year old had IgA on his RBCs which was detected using anti-IgA reagent, but an anti-IgG reagent that was not heavy chain specific also detected the IgA on the cells (weakly).  The cold LISS wash DAT and the Polybrene agglutination did not demonstrate the antibody in this particular case.
 
The 5 year old was treated with steroids.
 
Catherine

Hi Sara,
The first clue that the antibody may be anti-G, or anti-C+G, rather than anti-C+D, is indeed that the titre of the anti-C is higher than that of the anti-D, but the fact that the anti-C titre is higher than that of the anti-D is only a clue. It could be that you actually have an anti-C+D where, coincidentally, the anti-C titre is higher than the anti-D. It is absolutely essential, therefore, that you can prove that no anti-D is present.
One way of doing this is to divide the patient's plasma sample into two.
The first sample is adsorbed using Ro red cells treated with a proteolytic enzyme, such as papain or ficin, which would adsorb out any anti-G and any anti-D present, but would leave any anti-C present. At the end of the adsorption process (about 4 cycles), this plasma is tested against r'r red cells by IAT. If there is a positive reaction, then the original plasma contained anti-C and, possibly, anti-G. If there is a negative reaction, then the original plasma contained, possibly, anti-G and anti-D, but not anti-C.
The second sample is adsorbed using r'r red cells treated with a proteolytic enzyme, such as papain or ficin, which would adsorb out any anti-G and any anti-C present, but would leave any anti-D present. At the end of the adsorption process (about 4 cycles), this plasma is tested against Ro red cells by IAT. If there is a positive reaction, then the original plasma contained anti-D and, possibly, anti-G. If there is a negative reaction, then the original plasma contained, possibly, anti-G and anti-C, but not anti-D.
So, if there are no reactions with the plasma adsorbed with Ro red cells when tested with r'r red cells, and no reactions with the plasma adsorbed with r'r red cells when tested with Ro red cells, then the original plasma contained only anti-G.
If there is a reaction with the plasma adsorbed with Ro red cells when tested with r'r red cells, and also a reaction with the plasma adsorbed with r'r red cells when tested with Ro red cells, then the original plasma contained both anti-C and anti-D (and may also have contained an anti-G).
In all cases, however, you would give cross-match compatible C Negative, D Negative blood (you would still have to perform a serological cross-match, because there are some EXTREMELY rare donors around who are C Negative, D negative, but G POSITIVE.
As far as obstetric patients are concerned, both anti-C and anti-G usually cause far less severe haemolytic disease of the foetus and newborn (unless they have an unusually high titre), than does anti-D. However, it is important that the pregnant lady is offered prenatal and postnatal anti-D immunoglobulin prophylaxis, so that they do not get immunised against the D antigen.
I hope that this rather long and complicated post helps in some way, but, if you need to know more, please do not hesitate to ask more questions.

1.  Complex policy difficult for generalists to remember over time - easy to miss one that "should have been done"
2.  Hard to remember why a Fetal screen may be "very" positive when they no longer remember much about Rh neg (weak D positive).
 
I can relate to the above comments.  Everyone in my lab is a generalist.  They work hard and do their best but it's easy to forget.  I didn't understand weak and partial D until recently.  (I think I understand now!)
 
Fortunately we are small and there are not many of us so I can contact everyone with a weak-D policy in-service/mini-lecture.  
 
Some may feel this is a waste of testing - but it isn't very many pts anymore anyway and I would just rather "know" about these pts up front anyway.
 
I would rather know about these patients too...

I have a question about reporting 1+ or 2+ Rh reactions on the Provue as Rh positive.  
 
Page 4 of the 2005 AABB “Guidelines for Prenatal and Perinatal Immunohematology” states:    "Only when prenatal tests for Rh are unequivocal and clearly reactive (=/>2+) should the woman be considered Rh-positive.”
 
Dr. Joe Chaffin, The Blood Bank Guy, also states a similar opinion in his excellent podcast "Weak in the D's".  Here is a link to his podcast:
 
http://www.bbguy.org/podcast/1012/1012podcast.asp
 
The podcast is 41 minutes long, and if you don't have 41 minutes, skip to 34.12 minutes into the podcast.  That's where he starts talking about OB patients.  At 35.30 minutes into the podcast, he says that transfusion services should consider a lower threshold of positivity for calling Rh negatives--some places call a 1+ reaction or lower in tube testing Rh negative and a 2+ reaction or lower in gel testing Rh negative.  The risk here is giving Rh negative blood when Rh positive blood can be given, but calling these weak Rh reactions Rh negative lowers the risk of immunizing the patient.
 
I am interested in this because last week I realized I didn't have a weak D policy, except that we only perform weak D testing on cord bloods if the mom and baby test Rh negative. 
 
Last week we reported an OB patient as Rh negative, using tube testing with Ortho anti-D bioclone.  The patient's physician informed us that the patient was determined to be Rh positive 2 years ago when the patient had her first child.  I called the lab that performed that testing and found it was a 1+ reaction on the Echo Galileo.  The lab reported that the patient was “Rh Positive by Weak-D test (formerly Du).  RhoGam is not indicated for this patient”.  
 
We use the Ortho MTS gel cards for ABO/Rh testing (manual method) as well as tube testing with Ortho reagents, so we repeated the patient's testing using the gel method, and saw a 1+ reaction for the Rh.  When we performed the tube weak D test, we also saw a 1+ reaction. 
 
(An aside--we are a small lab, performing about 100 type and screens per month, about 40 crossmatches per month, 10 cord bloods per month.  I have been trying to phase the MTS ABD Reverse cards out.  The tube method is more versatile, it is faster in emergencies and according to a cost analysis I did, the tube method is ½ the price of the gel ABO/Rh method.  However, the lab is staffed with generalists, and I have been told it’s better for generalists to use the gel method—no chance of forgetting to add the reagent and more consistency.  We perform antibody screens using the gel method because it is more sensitive (although I realize the gel antibody screen method has its pitfalls such as being a LISS method and possibly missing anti-E and anti-K sometimes, etc.)
 
Anyway, I have come to realize that I need to write a weak-D policy, and I am thinking of including these points: 
Perform weak D testing only on cord bloods when mom and baby are Rh negative, on Rh negative moms when the FMH screen suggests the mom may be weak D positive, and when investigating discrepancies such as the OB patient last week. Calling Rh results less than 2+ in gel and less than 1+ in tube, Rh negative. When the Rh results are less than 2+ in gel and less than 1+ in tube, reporting the Rh as negative and including a comment that indicates the Rh type is weak and atypical and if the patient is a blood donor, the patient would be considered Rh positive, but if the patient is an OB patient or a recipient, the patient should be considered Rh negative. There is a CBBS posting about when the AABB changed the weak D regulations in 2002.  Dr. Judd is quoted as saying that, when it was decided in 2002 that weak D testing was no longer needed to be performed on OB patients, all of a sudden, patients that had been D positive, were suddenly D negative, and this was in the same facility.  Dr. Judd is quoted as saying that these patients were informed of their options...that is, where previously they were D positive and did not require RhIG, they were now D negative, and they could opt to receive RhIG or not...they needed to sign a form.......I hope I remember that correctly....
 
I would like opinions!
 
Thank you!
 
Catherine

There is an article on page 650 of the March 2014 Transfusion journal about a 14-year retrospective study at Beth Israel Deaconess Medical Center, Boston Massachusetts that looks at the anti-D alloimmunization rate in D negative patients who received D positive platelets.
 
The article is interesting because it points out the low alloimmunization rate in these patients.  For those of you without easy access to this journal, I will summarize:
 
The article reminds us that most (85%) platelet units transfused in the US are apheresis platelets, and apheresis units contain less than 0.001 mL RBCs, whereas platelet units from WB typically “contain a few tenths of a milliliter of RBCs”.  There is less exposure to the Rh antigen in apheresis platelets.
 
In the study, of 130 D negative patients that received prestorage LR apheresis D positive platelets, none formed anti-D “as shown by negative antibody screens at least 4 weeks after the incipient transfusion.” The patients were 52% male and 48% female.   43% were immunosuppressed and 57% were immunocompetent. 
 
The study started with 626 patients but many had to be eliminated because didn’t conform to the study’s requirements.
 
Of those patients that were eliminated,  354 patients were eliminated  because an antibody screen was not performed greater than 4 weeks after transfusion.  The antibody screen may not have been done because of death, discharge home, etc.  The authors state that this population that was eliminated may have made a difference in the outcome of the study if an antibody screen had been done greater than 4 weeks after transfusion and the population included.
 
However, their conclusion is that the findings “support the use of D+ apheresis PLTs irrespective of Rh status, D+ or D-, in all patient populations without the need for RhIG immunophophylaxis.
 
I think this is interesting and so decided to make a post….

Ha!  Thanks Malcolm! 
 
Concerning weak D and partial D, compared to what I did understand, I understand a lot.  Compared to all there is to understand, I understand nothing.... :confuse:
 
and I hope your family is okay....
 
Catherine

There is an article on page 650 of the March 2014 Transfusion journal about a 14-year retrospective study at Beth Israel Deaconess Medical Center, Boston Massachusetts that looks at the anti-D alloimmunization rate in D negative patients who received D positive platelets.
 
The article is interesting because it points out the low alloimmunization rate in these patients.  For those of you without easy access to this journal, I will summarize:
 
The article reminds us that most (85%) platelet units transfused in the US are apheresis platelets, and apheresis units contain less than 0.001 mL RBCs, whereas platelet units from WB typically “contain a few tenths of a milliliter of RBCs”.  There is less exposure to the Rh antigen in apheresis platelets.
 
In the study, of 130 D negative patients that received prestorage LR apheresis D positive platelets, none formed anti-D “as shown by negative antibody screens at least 4 weeks after the incipient transfusion.” The patients were 52% male and 48% female.   43% were immunosuppressed and 57% were immunocompetent. 
 
The study started with 626 patients but many had to be eliminated because didn’t conform to the study’s requirements.
 
Of those patients that were eliminated,  354 patients were eliminated  because an antibody screen was not performed greater than 4 weeks after transfusion.  The antibody screen may not have been done because of death, discharge home, etc.  The authors state that this population that was eliminated may have made a difference in the outcome of the study if an antibody screen had been done greater than 4 weeks after transfusion and the population included.
 
However, their conclusion is that the findings “support the use of D+ apheresis PLTs irrespective of Rh status, D+ or D-, in all patient populations without the need for RhIG immunophophylaxis.
 
I think this is interesting and so decided to make a post….

I have a question about reporting 1+ or 2+ Rh reactions on the Provue as Rh positive.  
 
Page 4 of the 2005 AABB “Guidelines for Prenatal and Perinatal Immunohematology” states:    "Only when prenatal tests for Rh are unequivocal and clearly reactive (=/>2+) should the woman be considered Rh-positive.”
 
Dr. Joe Chaffin, The Blood Bank Guy, also states a similar opinion in his excellent podcast "Weak in the D's".  Here is a link to his podcast:
 
http://www.bbguy.org/podcast/1012/1012podcast.asp
 
The podcast is 41 minutes long, and if you don't have 41 minutes, skip to 34.12 minutes into the podcast.  That's where he starts talking about OB patients.  At 35.30 minutes into the podcast, he says that transfusion services should consider a lower threshold of positivity for calling Rh negatives--some places call a 1+ reaction or lower in tube testing Rh negative and a 2+ reaction or lower in gel testing Rh negative.  The risk here is giving Rh negative blood when Rh positive blood can be given, but calling these weak Rh reactions Rh negative lowers the risk of immunizing the patient.
 
I am interested in this because last week I realized I didn't have a weak D policy, except that we only perform weak D testing on cord bloods if the mom and baby test Rh negative. 
 
Last week we reported an OB patient as Rh negative, using tube testing with Ortho anti-D bioclone.  The patient's physician informed us that the patient was determined to be Rh positive 2 years ago when the patient had her first child.  I called the lab that performed that testing and found it was a 1+ reaction on the Echo Galileo.  The lab reported that the patient was “Rh Positive by Weak-D test (formerly Du).  RhoGam is not indicated for this patient”.  
 
We use the Ortho MTS gel cards for ABO/Rh testing (manual method) as well as tube testing with Ortho reagents, so we repeated the patient's testing using the gel method, and saw a 1+ reaction for the Rh.  When we performed the tube weak D test, we also saw a 1+ reaction. 
 
(An aside--we are a small lab, performing about 100 type and screens per month, about 40 crossmatches per month, 10 cord bloods per month.  I have been trying to phase the MTS ABD Reverse cards out.  The tube method is more versatile, it is faster in emergencies and according to a cost analysis I did, the tube method is ½ the price of the gel ABO/Rh method.  However, the lab is staffed with generalists, and I have been told it’s better for generalists to use the gel method—no chance of forgetting to add the reagent and more consistency.  We perform antibody screens using the gel method because it is more sensitive (although I realize the gel antibody screen method has its pitfalls such as being a LISS method and possibly missing anti-E and anti-K sometimes, etc.)
 
Anyway, I have come to realize that I need to write a weak-D policy, and I am thinking of including these points: 
Perform weak D testing only on cord bloods when mom and baby are Rh negative, on Rh negative moms when the FMH screen suggests the mom may be weak D positive, and when investigating discrepancies such as the OB patient last week. Calling Rh results less than 2+ in gel and less than 1+ in tube, Rh negative. When the Rh results are less than 2+ in gel and less than 1+ in tube, reporting the Rh as negative and including a comment that indicates the Rh type is weak and atypical and if the patient is a blood donor, the patient would be considered Rh positive, but if the patient is an OB patient or a recipient, the patient should be considered Rh negative. There is a CBBS posting about when the AABB changed the weak D regulations in 2002.  Dr. Judd is quoted as saying that, when it was decided in 2002 that weak D testing was no longer needed to be performed on OB patients, all of a sudden, patients that had been D positive, were suddenly D negative, and this was in the same facility.  Dr. Judd is quoted as saying that these patients were informed of their options...that is, where previously they were D positive and did not require RhIG, they were now D negative, and they could opt to receive RhIG or not...they needed to sign a form.......I hope I remember that correctly....
 
I would like opinions!
 
Thank you!
 
Catherine

Well, we just had another case that looks like cefotetan antibody.  Should get the test results in the next day or so.  This one was a woman in a couple of weeks ago for bowel surgery.  When she came back in this week with nausea and vomiting she had a bili of 7 so they did a DAT, LDH etc. Her Hgb was about 10.  The next morning it was 5.6!  When they ordered blood and the tech got a negative Ab screen, she put together the clues that the patient had a positive DAT the day before and a recent inpatient visit with this crashing hemolysis so checked drug history and found cefotetan given at the time of the surgery.  She notified the hospitalist and they put her on steroids promptly so her hgb is stabilizing but her bili was up to 11 today.
 
Does anyone have a good case study or bullet point list that is more from the clinical presentation side rather than the labwork side?  I would like to try to help ED doctors know to think of this but it seems like the patients present in a lot of different ways.  This is our 3rd case in 5 years and the Blood Bankers have caught them all.  BTW, these 3 patients are all A neg (2) or A pos (1).  Is this just coincidence or are group A people more at risk of this hemolytic anemia?

Hi Mabel,
 
IgA can activate complement via the properdin or alternative complement pathway.  JoAnn Moulds reminded us of this at the "Who DAT" session at the 2013 AABB meeting in Denver last October. 
 
At this session Patricia Arndt spoke about negative DATs in patients with clinical hemolysis.  Patricia Arndt mentioned more sensitive methods that can demonstrate antibody on RBCs in these patients.  These methods include cold LISS wash DAT method, flow cytometry, direct Polybrene test, also testing with anti-IgA and anti-IgM reagents.  Anti-IgA and anti-IgM reagents are not commercially available in the US, but Pat's lab has these reagents for research and special cases. 
 
But Pat also mentioned that anti-IgG reagents that are not heavy-chain specific can pick up IgA and IgM because these reagents may have antibodies to kappa and lambda light chains and can react with IgA and IgM light chains.
 
Pat presented a case of a 5 year old with clinical hemolysis (Hgb = 6.4, bilirubin high, LDH high, etc) and a negative DAT.  It turned out this 5 year old had IgA on his RBCs which was detected using anti-IgA reagent, but an anti-IgG reagent that was not heavy chain specific also detected the IgA on the cells (weakly).  The cold LISS wash DAT and the Polybrene agglutination did not demonstrate the antibody in this particular case.
 
The 5 year old was treated with steroids.
 
Catherine

Hi Mabel,
 
IgA can activate complement via the properdin or alternative complement pathway.  JoAnn Moulds reminded us of this at the "Who DAT" session at the 2013 AABB meeting in Denver last October. 
 
At this session Patricia Arndt spoke about negative DATs in patients with clinical hemolysis.  Patricia Arndt mentioned more sensitive methods that can demonstrate antibody on RBCs in these patients.  These methods include cold LISS wash DAT method, flow cytometry, direct Polybrene test, also testing with anti-IgA and anti-IgM reagents.  Anti-IgA and anti-IgM reagents are not commercially available in the US, but Pat's lab has these reagents for research and special cases. 
 
But Pat also mentioned that anti-IgG reagents that are not heavy-chain specific can pick up IgA and IgM because these reagents may have antibodies to kappa and lambda light chains and can react with IgA and IgM light chains.
 
Pat presented a case of a 5 year old with clinical hemolysis (Hgb = 6.4, bilirubin high, LDH high, etc) and a negative DAT.  It turned out this 5 year old had IgA on his RBCs which was detected using anti-IgA reagent, but an anti-IgG reagent that was not heavy chain specific also detected the IgA on the cells (weakly).  The cold LISS wash DAT and the Polybrene agglutination did not demonstrate the antibody in this particular case.
 
The 5 year old was treated with steroids.
 
Catherine

Hi Mabel,
 
IgA can activate complement via the properdin or alternative complement pathway.  JoAnn Moulds reminded us of this at the "Who DAT" session at the 2013 AABB meeting in Denver last October. 
 
At this session Patricia Arndt spoke about negative DATs in patients with clinical hemolysis.  Patricia Arndt mentioned more sensitive methods that can demonstrate antibody on RBCs in these patients.  These methods include cold LISS wash DAT method, flow cytometry, direct Polybrene test, also testing with anti-IgA and anti-IgM reagents.  Anti-IgA and anti-IgM reagents are not commercially available in the US, but Pat's lab has these reagents for research and special cases. 
 
But Pat also mentioned that anti-IgG reagents that are not heavy-chain specific can pick up IgA and IgM because these reagents may have antibodies to kappa and lambda light chains and can react with IgA and IgM light chains.
 
Pat presented a case of a 5 year old with clinical hemolysis (Hgb = 6.4, bilirubin high, LDH high, etc) and a negative DAT.  It turned out this 5 year old had IgA on his RBCs which was detected using anti-IgA reagent, but an anti-IgG reagent that was not heavy chain specific also detected the IgA on the cells (weakly).  The cold LISS wash DAT and the Polybrene agglutination did not demonstrate the antibody in this particular case.
 
The 5 year old was treated with steroids.
 
Catherine