Neonatal Hematology

Question 1

Hemolysis in NEC– pathophysiology?

Answer 1

T-antigen activation:

Red blood cells have N-acetyl neuraminic acid attached to a galactose molecule on the T-antigen on the RBC membrane

Neuraminidase bacteria/viruses cleave the neuraminic acid, which activates the T-antigen on RBCs

Naturally occurring anti-T antibodies tag RBCs for destruction–> t-antigen activation occurs in hemolytic uremic syndrome as well

Question 2

Treatment of hemolysis in NEC

Answer 2

T-antigen activation mediated hemolysis in NEC (naturally occurring anti-T antibodies opsonization).

Washed RBC transfusion (wash away the plasma, which may carry any antibodies)

Question 3

What is Fetal/Neonatal Alloimmune Thrombocytopenia (FNAIT)

Answer 3

Maternal antibodies form against the paternal HPA (human platelet antigen) on fetus/infant’s blood cells

Question 4

Most common antibody implicated in FNAIT (fetal/neonatal alloimmune thrombocytopenia)?

Answer 4

Anti-HPA-1a antibodies (Human Platelet Antigen-1a) in caucasians

In Asians mothers, predominantly anti-HPA-4b antibodies

Question 5

What are common manifestations of FNAIT in the infant? Can it happen in the first pregnancy?

Answer 5

Clinical signs of thrombocytopenia– petechiae; life-threatening intracranial hemorrhage (can be devastating)

Unlike Rh incompatibility, can occur in the first pregnancy

Question 6

Preventative measures specifically against intracranial hemorrhage for babies affected by fetal/neonatal alloimmune thrombocytopenia?

Answer 6

Maternal treatment with IVIG to prevent transfer of antibodies to fetus

Question 7

What is the sole predictor of risk of hemorrhage in fetuses/neonates affected by NAIT in subsequent pregnancies?

Answer 7

Intracranial hemorrhage in siblings affected by NAIT is the only predictor of hemorrhaging in subsequent siblings