was seen by her OB-GYN at 10 weeks of gestation with her first pregnancy. Resuit
ID: 253551 • Letter: W
Question
was seen by her OB-GYN at 10 weeks of gestation with her first pregnancy. Resuits of her prenatal workup indicate she is group O, I she is given 300 ug of RhIG. The pregnancy proceeds normally, and she delivers a 7 ikepeat testing at 28 weeks continues to indicate a ne ative antibody scree, antd at 39 weeks of gestation. Results of cord blood tests are as follows: Results antibody an screen. oz boy Anti-A Anti-B Anti-D Weak D Weak D control DAT Mother's Sample Screen cells 3+ 0 0 Weak positive Infant hemoglobin is 17.3 g/dL, and bilirubin is 0.6 mg/dL. 1. Does this infant have HDFN? If so, what is the most probable cause? 2. What could be causing the positive screen result? How would you confirm?Explanation / Answer
1) yes the infant is suffering from HDFN or hemolytic disease of the fetus and newborn.
Given that the mother is D-negative, i.e. the mother does not carry the D antigen on her RBC's.
Now in this case looks like the fetus is D positive. Although till 28 weeks no antibodies against D antigen was raised by the immune system, sometime after that antibodies were formed.
These antibodies attack the red blood cells in the fetal circulation, breaking down and destroying them.? Thus resulting in the increase in hemoglobin and bilirubin in the infants blood.
2) Presence of antibodies against the D antigen is causing the positve screen test and can be confirmed by DAT or two coombs test.
TheDAT test uses anti-human antibodies, which are produced by immunizing non-human species with human serum, that bind to human antibodies, commonly IgG or IgM.
Animal anti-human antibodies bind to human antibodies that are fixed onto antigens on the surface of red blood cells (D-antigen), and in the positive test tube conditions this can lead to agglutination of RBCs.?
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