How is hemolytic disease of the newborn (HDN) prevented?

Updated: Dec 28, 2017
  • Author: Sameer Wagle, MBBS, MD; Chief Editor: Muhammad Aslam, MD  more...
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Answer

Consider the following in patients with hemolytic disease of the newborn (HDN):

  • Rh immune globin (RhIG) was licensed in 1968 in North America after several studies demonstrated its effectiveness in preventing Rh alloimmunization when administered to the mother within 72 hours of delivery. The current standard is to administer RhIG to all unsensitized Rh-negative women at 28 weeks' gestation with an additional dose administered soon after birth if the infant is Rh-positive, irrespective of the ABO status of the baby. RhIG is not indicated for mothers with weak or partial D status because most are not at risk for alloimmunization. [60]

  • The standard dose of RhIG is 300 mcg and is increased (300 mcg for every 25 mL of fetal blood in maternal circulation) based on the amount of fetomaternal hemorrhage, which can be quantified using the Kleihauer-Betke technique. Because only 50% of pregnancies with excess fetomaternal hemorrhage can be identified by clinical risk factors, routine screen for excess fetomaternal hemorrhage (FMH) is undertaken in all Rh negative women. However, if the incidence of excess FMH is 0.6%, the maximum risk of sensitization is 0.1%, suggesting routine assessment for excess FMH may not be justified.

  • Also administer RhIG to unsensitized Rh-negative women after any event known to be associated with transplacental hemorrhage such as spontaneous or elective abortion, ectopic pregnancy, amniocentesis, chorionic villous sampling, fetal blood sampling (FBS), hydatiform mole, fetal death in late gestation, blunt abdominal trauma, and external cephalic version. The indications for first trimester threatened abortion and ectopic pregnancy with no cardiac activity are not cost effective and are left to the clinician. [21]

  • No more than 5 units of RhIG should be given by intramuscular route in 24-hour period. An intravenous preparation is now available for administration of large doses. If RhIG was inadvertently omitted after delivery, the protection can still be offered if given within first 4 weeks. A repeat dose is not needed if delivery occurs within 3 weeks after administration of RhIG during antenatal period. The current incidence of Rh immunization stands at 0.1% with the above recommendations.

  • Most RhIG is derived from human plasma obtained from sensitized women or male donors sensitized with RhD positive cells. Because it is a blood product, it has risks of transmission of viral infections such as hepatitis C and may not be acceptable in some religious denomination. Hence 2 monoclonal anti-D antibodies derived from recombinant technology, BRAD-1 and BRAD-3, are being tested in clinical trials. A new novel polyclonal recombinant antibody, rozrolimupab has also been tested in phase I and II clinical trials with no adverse effects. [78]


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