RH Negative

[Lazmar]

Hi,

I am RH negative.  I had a successful pregnancy, and two subsequent miscarriages. I am currently 15 wks pregnant.  I was not sensitized at the beginning of this pregnancy.  I had spotting in week 4 and was given Rhogam.  I had a huge bleeding episode in wk 12.  I was not given Rhogam again as it was still in my system determined by blood test.  I was bleeding brown blood for the past 3 wks and asked my my ob if I should have Rhogam again.  Bloodwork was taken along with a test called the Kleihauer-Betke test.  This test showed that I had fetal blood cells in my system.  I am worried that the Rhogam I got in wk 4 may not have been strong enough.  I read if an ounce of fetal blood mixes in with yours you would need two shots of Rhogam.  I did get the shot today.  I am worried if I become sensitized now.  Will it affect this pregnancy??  Any advice would be helpful.  Thanks.

[Yao Sun, MD, PhD]

As a neonatologist (baby specialist), this is not really my area of expertise: you should continue to discuss your concerns with the perinatologist.  In general, laboratory tests cannot distinguish between maternal Rh antibodies and externally administered antibodies like Rhogam.

[Lazmar]

Updating w/ more info. My blood for Kleihauer test was taken Friday 4/24 along w/ blood test. I forgot to call my Ob Monday and she called me Wednesday.  I took the rhogam shot along with another blood test on Thursday 04/30.  My doctor called me today and said I had positive antibodies in 4/24 blood test probably from the rhogam given weeks ago and the blood test from yesterday showed negative antibodies so it was good I got the Rhogam.  I am just paranoid if there was a slight chance I may have become or will become sensitized.  Can a lab differentiate between rhogam antibodies vs the one created by the mother?