ABO set up

[abeluchin]

Hi

I took care of a baby who's mother is B+ and baby is A+ with a DAST/Coombs+. The DAT was sent inarventently  since we only sent DAT in mother's with blood tupe O or rh negative. I was surprised to see this results since I have always understand that ABO incompatibility  that cause significant hemolysis is only produced when mother is O and baby is A or B group. The reason for this ABO incompatibility set is not too clear. I understand its because when mama is O and baby is A or B; IgG antibodies casn be produced during gestation that will cross the placentas . Unlike when mama is A and baby is B or mama is B and baby is A only igM antibodies are produce yhjat will not cross the placenta. I am not sure why this is  produced this way??

Any input or insights will be apreciated

 

[planonnp]

There can be minor antibodies present such as Kell and Duffy.  

[Stefan Johansson]

This is also my first thought, that the DAT+ is not related to the AB0 type but another antigen. 

[abeluchin]

No other antibodies were present in mother's circulation.

[gmavrogeorgos]

If mother's indirect coombs is negative , then maybe false positive result ?

[Ahmed morsy]

DCT IS NOT SPECIFIC neither 100% sensitive 

[Efe]

It can also occur in such setting but much less likely. 

[Cheryl Carlson]

According to Avery's text.  It is possible for Group A or B infants born to incompatable A or B mothers will have a small chance of a positive combs test, though unlikely to cause significant hyperbilirubinemia. 

"Infants born of ABO-incompatible mother–infant pairs who have a negative direct Coombs test appear to be at no greater risk for developing hyperbilirubinemia than their ABO-compatible counterparts (Ozolek et al., 1994), and the development of significant hyperbilirubinemia in such neonates should prompt an evaluation for a cause other than isoimmunization (Herschel et al., 2002). Similarly, group A or B infants born to incompatible group B or A mothers are not likely to manifest symptomatic ABO hemolytic disease, and less than 1% will have a positive direct Coombs test (Ozolek et al., 1994)."

[Abdul kasim jaleel ahmed]

First of all this not ABO incompatibility 

Think of Minor  blood groups mismatch and look for active hemolytic state (may be Reti & PS ) may help. THANKS