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Multiple Doses of RhoGAM

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6 months ago we had an Rh negative OB patient who delivered an Rh positive infant, and subsequently required 4 doses of RhoGAM. I'll also mention that we re-collected and re-tested to be sure. We also tested for weak D and she was indeed Rh negative. Her antibody screen was negative prior to her pregnancy. Now, 6 months after delivery and 4 RhoGAM doses, she is still exhibiting a strong anti-D. I contacted the manufacturer to see if they had any literature or information regarding how long the 4 doses could still be detected. They only sent me a link to some online information that I had already read! I know the half-life is only about 3 weeks, and everything I've read says it may be detected up to 12 weeks post injection. Additionally, we did a titer on the anti-D and it was 8, which leads me to believe this is an immune anti-D and not passive from RhoGAM since RhoGAM normally will not titer beyond 4. The physician and I have discussed it and the patient will be tested again in another 3 months. Has anyone had a similar experience? At this point my only explanation is that she could have developed the anti-D AFTER our initial testing and PRIOR to her 28-week prenatal dose.

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A little personal experience here.  As I've mentioned in the past, my wife was a labor and delivery nurse so you can guarantee that any pregnancy she had would be complicated.  When she was pregnant with our son, baby #1, we were not following her closely because of the Anti-K I had detected while still in school because I am K neg.  She had donated some blood for me to test during one of my blood bank classes.  It was the result of previous transfusions.  Anyway, back to the story.  Jason was delivered 6 months prior to the start of antenatal RhIG injections so that never happened.  The delivery was via C-section and the physician thought there was very little bleeding so only one vial of RhIG was issued post delivery.  At the time the facility she delivered at, where she worked, did not routinely perform FMH determinations.  I worked at another facility was I was not involved.  Fast forward to a couple of years later.  I had been using blood from Janice for students.  Her anti-K was a little unusual in that it showed up at room temp, went away at 37o and then returned at the AHG phase.  A student submitted his workup indicting an anti-D as well as the anti-K.  Needless to say I was surprised and repeated the test twice using 2 different panels and confirmed that the anti-D was there.  She had fallen while skiing when she was about 6 months along so our best guess that she had either received her RhIG injection to late or to little was provided.  The anti-D became a bigger issue 4 years later when our daughter was born but that's a story for another time.


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  • 2 weeks later...
On 8/14/2021 at 8:32 AM, galvania said:

Why did she need 4 doses ?

I suspect it was one dose of 4-300 mcl.  Since we're not pharmacists, we sometimes fail to use the correct terminology when speaking of a "dose".  This amount would have been indicated from the results of the Kleihauer-Betke stain for fetal hemoglobin.

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