SBB 561 HDFN

• Hgb: 16.9 +/- 1.6 g/dL
• 4-8 weeks: 8 g/dL

• Last 45-70 days
• 53-95% at birth
• Premature infants have higher Hgb F and lower Hct

• At birth, Hgb F results in poor tissue oxygenation. O2 curve is to the left.
• Hgb A replaces Hgb F and O2 dissociation curve shifts to the right, giving up more O2 to tissues

Neonate marrow takes 2-3 weeks to respond to RBC need.

Adults take 4-6 days

Occurs when the mother has an antibody capable of crossing the placental barrier that is specific to an antigen present on the RBC of the fetus.

FC region of antibody causes sensitization by active transport of antibodies (not diffusion). 

Fetal cells become coated with IgG alloantibody which destroys RBC's before and after birth.

• Rh
• anti-K, -Fya, -s, etc. 
• ABO (most common) - May protect baby from other more severe HDFN

• Erythrobastosis fetalis
• Hydrops fetalis
• Seere Anemia
• Bilirubinemia 
• Enlarged liver and Spleen

• Increased RBC destruction
• results in 
• Increased RBC production
• results in 
• Increased nRBC's

Generalized edema of the fetus

Not a problem when in utero because Mom's liver can conjugate the bilrubin.

Newborn: Immature liver still lacks Uridine diphosphoglucuronyl transferase, therefore is unable to conugate the bilirubin. The unconjugated (indirect) bili may become too high resulting in toxic levels. Too high may result in kernicterus.

Excess indirect (unconjugated) bilirubin leaves blood stream and deposits in the brain tissue

• TNS
• ABID (as needed)
• Titer for any clinically significant Ab. - Perform throughout pregnancy. Run first sample in parallel with new sample. 2 tube (4 fold) increase is clinically significant. 
• If 4 fold titer increase, amniocentesis or other additional testing may be needed to determine severity.

• Identifies intrauterine hemolysis and fetal well being is the level of bili pigment foun in the amniotic fluid. 
• The higher the pigment concentration, the more severe the hemolysis. 
• Usually performed on those with a titer >16.

A change in opitical density (ΔΟD₄₅₀) value of the amniotic fluid in the upper mid zone of the graph indicates the need for fetal blood sampling.

Amniotic fluid is subjected to a spectrophotometric scan at steadily increaing wavelengths so that the change in the OD at 450nm can be calculated.

• Middle cerebral artery peak systolic velocity (MCA-PSV) is measured.
• MCA >1.5 multiples of the Median (MoM)indicates moderate to severe anemia
• Fetal anemia results in: 
• Increased cardiac output & blood flow
• Decreased blood viscosity
• Preferred in mothers with anti-K, as amniotic fluid analysis does not correlate well with the degree of fetal anemia.

• Hgb <10 gm/dL
• Usually repeated every two weeks until delivery

R2R2 has highest concentration

• Lewis
• Sda
• Ch/Rg

• A, B, H
• I, P1, Vel

• LW
• i

• O Neg 
• Antigen neg for corresponding antibody
• XM compatible with Mom
• CMV neg or leukoreduced
• <5-7 days
• Irradiated (prevents GVHD)
• HgbS neg
• Prefer frozen, deglycerized with 80% Hct -

• High incidence antigen on fetus (k, U, Kpb, etc.) may require Mom's washed RBC's.
• NOT DAD!

1. Intraperitoneal: RBC infused into fetal abdomen and absorbed into circulation

2. Intravascular: RBC are infused directly into umbilical vein using ultrasound guidance. Quicker response

pools of human plasma predominately of IgG anti-D. 

Prevents mom from making anti-D by suppressing immune response.

• Full Dose: 300 μg of anti-D
•     - Protects agains 30 mLs of D positive whole blood or 15 mL's of Packed RBC's)

• Mini Dose: 50 μg
•    - Protects against 2.5 mL's of D positive whole blood
•    - Used for 1st trimester abortion or miscarriage

<4 likely rhogam

• Screen detects Rh+ cells in Mom's circulation. 
• Chemically modified anti-D is added to Mom's washed cells and incubated. 
• Use R2R2 indicator cells to allow rosetting around anti-D that has attached to Rh positive cells

*Not recommended for weak D pos

Detects the presence of Hgb F after a fetomaternal bleed occurrence.

Acid elutes HgA but does not affect Hgb F, therefore cells containing Hgb F will stain and appear ghost-like

Fetal cells counted/Total RBC's counted x 100

Elution to identify antibody coating baby's red cells

Low incidence antibody by testing eluate against fathers cells

Kleihauer Betke stain is required to detect fetal bleed

• Resp distress
• DIC
• Sepsis
• Hyperbilirubinemia - The level, NOT the cause, influences the decision.
• Hemolysis due to G-6PD deficiency, hereditary spherocytosis, hemoglobinopathies

• Moms serum/plasma
• or
• Baby's serum/plasma or eluate IF mom's sample is not available

• Compatible with Mom's ABO antibodies and unexpected Ab's.
• Usually Group O
• <5-7 days 
• If Ab to high incidence, use mom's washed packed cells or mother's compatible sibling, or antigen neg blood. Incompatible is last resort
• If mom and baby are ABO identical, group specific may be used
• Irradiated
• CMV Neg
• Typically double the baby's blood volume is used

• 1. Total Volume needed:
• Weight in kg x 85 x 2 = ___ 
• 2. Absolute volume of RBC needed to give a 50%Hct = #1 answer /2
• 3. Actual volume of RBC's needed =          #2 answer / 0.7
• 4. Actual volume of FFP =  #1 - #3

OR - 

5. Weight of PRBC x Hct  = unknown x Hct wanted; subtract the answer from the original volume of RBC

The unit you pick weights 300cc with a 75% Hct (CPDA-1). So, 

• 300 x .75 = 225
• 225 / 0.5 = 450cc

• For plasma -
• 450 - 300 = 150cc

• Harmening 6th ed. 
• pages: 427-438