Hemolytic Disease of the Fetus and Newborn

Where does the infant inherits their antigen from

biological father

The mother has what corresponding ig antibody

IgG

HDFN or erythroblastosis fetalis

occurs when IgG antibodies produced by the mother cross the placenta and destroy the baby’s RBCs when the RBCs contain antigen specific for the antibody.

What results are included for HDFN or erythroblastosis fetalis

•RBC lysis

•Elevated indirect bilirubin

•Anemia (decreased Hgb/Hct)

•Cardiac failure and/or hydrops fetalis as a result of anemia

Mothers livers handles whet before delivery of the baby

bilirubin metabolism

Baby immature liver is not able to handle what that can result in jaundice

bilirubin load

If a baby have jaundice because of bilirubin load can lead to what

•Deafness

•Mental retardation

•Kernicterus – brain damage associated with bilirubin levels in the range of 16-20 mg/dL

•death

What are the lab results for Rh HDFN

POS DAT

Increase Bilirubin

What does D neg moms produce when pregnant with an d pos baby

They produce antibodies

Who does the antibody attack

Attack second baby or donor enc if d pos

What is needed to avoid kernicterus

Exchange Transfusions

What is the most common form of HDFN

A or B babies born to O type mother- mild diseases

How are infants that have bilirubin are treated

Phototherapy

What do amniocentesis test on amniotic fluid determine

To determine feta lung maturity

What are the three alternatives for amniocentesis test results on amniotic fluid

Let the pregnancy continue

Perform intrauterine transfusion

Induce early labor

What blood supply is given to an intrauterine transfusion

Antigen neg blood

What are the units selection for intrauterine transfusion

Group O and D neg

Neg for antigen corresponding to maternal antibodies

Irradiated

CMV neg

Hbg S neg

Fresh < 7 days old

What to ABO during HDFN

•Increased Spherocytes

•Weak DAT or negative

•Delayed jaundice

•Bilirubin rarely >15 mg%

•1^st pregnancy can be affected

•Usually O mother with AB baby

What happens to Anti-D antibodies during HDFN

•Increased Retics

•DAT strong positive

•Immediate jaundice

•Bilirubin often >20 mg%

•Usually not 1^st pregnancy; D neg mother with D pos baby

Cord hemoglobin

hemoglobin-decisive factor in deciding whether to perform exchange transfusion

Bilirubin

most physicians perform exchange transfusion when level approaches 20 mg/dL

DAT

single most important diagnostic test in diagnosis of HDFN after birth

What make D type neg at IS

due to heavy coating of cord cells with maternal antibody (D and D control will be positive at AHG)

What is Amniocentesis

–Procedure in which a needle is inserted through the mother’s abdominal wall and uterus to extract fluid from the amniotic sac

How is total bilirubin measured in amniotic fluid

by the change in absorbance of the fluid at 450 nm

What are acceptable samples for Exchange Transfusion

Maternal sample-highest conc. of maternal antibody

Eluate from infant’s cells

Infant serum

What is the procedure for Exchange Transfusion

1.Replaces antibody coated cells (which would increase bilirubin levels if destroyed) with antigen negative cells

2.Reduces maternal antibody and bilirubin levels

3.Removes antibody-coated cells which would increase bilirubin levels when destroyed

Qualitative Screening- Rosette test

a suspension of maternal RBCs (which include a few Rh-positive fetal RBCs) is incubated with anti-D.  Anti-D binds to fetal RBCs. D-positive indicator cells are added that bind to the anti-D, forming a rosette around the fetal RBCs

Kleihaur-Betke acid elution
Fetal Stain- Quantitative

•Used to determine the amount of a fetomaternal hemorrhage.  Principle: fetal hemoglobin is resistant to acid elution.  A blood smear from the mother is made, then dipped in an acid buffer and stained with a counterstain.  The buffer lyses the mother’s cells (ghost cells) and does nothing to the fetal cells.