How is maternal alloimmunization treated in hemolytic disease of the newborn (HDN)?

Updated: Dec 28, 2017
  • Author: Sameer Wagle, MBBS, MD; Chief Editor: Muhammad Aslam, MD  more...
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As a rule, serial maternal antibody titers are monitored until a critical titer of 1:32, which indicates that a high risk of fetal hydrops has been reached. At this point, the fetus requires very intense monitoring for signs of anemia and fetal hydrops. In Kell alloimmunization, hydrops can occur at low maternal titers because of suppressed erythropoiesis, and, thus, a titer of 1:8 has been suggested as critical. Hence, delta-OD 450 values are also unreliable in predicting disease severity in Kell alloimmunization. [55]

Maternal titers are not useful in predicting the onset of fetal anemia after the first affected gestation. Large differences in titer can be seen in the same patient between different laboratories, and a newer gel technique produces higher titer results than the older tube method. Therefore, standard tube methodology should be used to determine critical titer, and a change of more than 1 dilution represents a true increase in maternal antibody titer. For all the antibodies responsible for hemolytic disease of the newborn (HDN), a 4-fold increase in any antibody titer is typically considered a significant change that requires fetal evaluation. [56]

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