Weak D policy

[Marianne]

Our transfusion services are working on a standardized Weak D policy.  We are trying to determine what age to use as the upper limit for women of child-bearing potential.  We would love to see what others are using to see if there is one that is used most commonly out there.  I would think 50 should be safe as in my opinion anyone older than that wanting to start over with a baby has way more problems than worrying about Anti-D!

[mollyredone]

Are you saying you perform weak-D testing on all females of child-bearing age?  Do you then send it out for genotyping to confirm that they are Type 1, 2, or 3 and cannot make anti-D?  We don't do any weak-D typing on females unless they have a positive FMH and then we cancel the FMH and order Fetal Hgb F.  We only do weak-D testing on babies if the mom is D-.  If the baby is weak-D pos, we still report out as D-, since we wouldn't perform a weak-D on an adult.  We haven't gotten into genotyping yet, although that is the guideline of ACOG.  There are a lot of interesting articles about it.

[Malcolm Needs ☆]

You are going to hate me mollyredone (if you don't already), but why all females of child-bearing AGE?  Surely, this should be (albeit a horrible phrase) child-bearing POTENTIAL?  A female of, for example, 5-years-old is NOT of child-bearing age, but she is most certainly of child-bearing potential, and, if she is D Negative, or expresses a variant D other than Weak D Types 1, 2 or 3, has the potential to produce an immune anti-D, given the correct stimulus.  Should she not be tested?..........or are you only talking about peri-partum cases - in which case I apologise and withdraw my comments (totally).

 

[David Saikin]

We do not do weak D testing on patients except for cord blood ABORh.  Our age cutoff for child-bearing potential (I like that phrase) is 50 yrs of age.

[Marianne]

Like Malcolm stated, we are using the "child-bearing potential", not "age", so it is that top age we need to determine.  I have seen 45-60yrs in different site policies over the years, so trying to find if there might an age in that range that appears to be most commonly used.

We are looking to implement genotyping following the recommendations presented in the article in Transfusion, March 2015, supported by ACOG and CAP/TMRC.  This is a big change but we have several very large hospitals in our system and we do see several female patients each year who have made Anti-D.

David-thanks for sharing the "50". 

[DebbieL]

We only do a Weak D on the mom if the FMH screen is very positive. Mom almost always turns out to be Weak D positive in these situations. If Weak D pos then we order HgB-F.

If mom and baby are both Rh negative, then we test the baby for Weak-D. If baby is Weak-D pos then we order a HgB-F on the mom because the FMH kit might not detect Weak-D.

We use 55 as the cutoff for childbearing. I wanted 50 but the CMO wanted 55 so he naturally won. I think he wanted the possiblity of childbearing out of the realm of possibility. We use that number when deciding whether to give Rh pos blood in a trauma situation. So if a woman is 56 she might get Rh Pos.

 

[Malcolm Needs ☆]

Listen to Connie Westhoff's podcast on Joe Chaffin's BloodBankGuy site - WOW - just WOW!!!!!!!!!!!!!!!!!!!!

[apfelblosm]

We use 50 years for our child bearing age/potential.  We only do weak D on moms with a positive rosette test.  Otherwise, we do it on only cord bloods who are initially D neg.

 

We have a policy that if a woman is less than or equal to 50 years of age and she has one of the following:

• History of being weak D positive
• Questionable IS result for D typing
• Anti-D series 4 and anti-D series 5 are discrepant on the NEO or Echo

Then the sample gets sent for genotyping for weak D.

 

[AMcCord]

On 4/25/2016 at 5:16 AM, David Saikin said:

We do not do weak D testing on patients except for cord blood ABORh.  Our age cutoff for child-bearing potential (I like that phrase) is 50 yrs of age.

Ditto

[mollyredone]

Sorry Malcolm, we would not send any female of child-bearing potential out for genotyping (which we are not doing yet anyway) unless they are/were pregnant.  I don't think ACOG is addressing 5 year olds.  Males would not be genotyped either.  Can't they form anti-D?  Even if it won't precipitate HDN.  The purpose of the genotyping is to prevent excessive use of Rhogam, as well as unnecessary utilization of Rh-negative PRBCs.

And our cutoff is <55.

P.S.  I was just referring to FMH in my original post.

[mollyredone]

On Monday, April 25, 2016 at 0:07 PM, apfelblosm said:

We use 50 years for our child bearing age/potential.  We only do weak D on moms with a positive rosette test.  Otherwise, we do it on only cord bloods who are initially D neg.

 

We have a policy that if a woman is less than or equal to 50 years of age and she has one of the following:

• History of being weak D positive
• Questionable IS result for D typing
• Anti-D series 4 and anti-D series 5 are discrepant on the NEO or Echo

Then the sample gets sent for genotyping for weak D.

 

Does that include 5 year olds?

[mollyredone]

One of the problems in the US is that we don't have a national database for blood types.  So if a patient were genotyped here as weak 1,2 or 3 and got Rh positive blood and no Rhogam, another hospital wouldn't know about it unless the patient presented a card from us stating her status.  Is there a national database in the UK, Malcolm?  At what age would you start genotyping females for weak type 1,2 or 3?  It would be so nice to have this standardized, but all we can do is call another hospital if the patient has been transferred to alert them of an antibody situation.  We do give the patients ID cards for their wallet, but that doesn't always get presented.

[Malcolm Needs ☆]

Yes mollyredone, we do have a national database (called SpICE - I think I've got the capitals and lower case letters in the right place - but I'm not sure), but it has only been going for a few years, and so not everyone is on it.

Weak D Types 1, 2 and 3 can (almost) be sorted by the anti-D typing reagents we use, so it is unusual for these to be "diagnosed" by molecular techniques.  Everything else in the way of "odd" D types are now called variant D, and so are treated as D Negative, unless we (the RCI Laboratories) specifically require to know just what kind of Weak or Partial D type it is - and if the IBGRL agree to do it!.

[Mabel Adams]

Malcolm, do the hospitals there have this capability to "almost" determine the weak D status or just your reference lab?  Are you referring to the partial D kit or some other reagent?

[Malcolm Needs ☆]

Yes Mabel, I am talking about the Partial D kit.  As far as the hospitals are concerned, some have bought this kit, and some have not, so it is, quite literally, "yer pays yer money and yer takes yer choice!" in their case.

[tbostock]

Ours is 60.  Insane.