Fetus
- Unborn
- Relies on mom for kidney and liver function, waste removal, and oxygenation
- has placenta and cord
- difficult to collect transfusion specimen
Newborn
- infant from birth-4mth of age
- Ab still developing
- no maternal waste management to aid in bodily functions
- specimens available by heel stick or. cord (at birth)
List order of infant blood testing
- Fwd ABO type
- DAT
- Elution
DAT testing in infants
IgG only, no complement
ABO HDN
- most common
- least severe
Rh HDN
- least common
- most severe
Other types of HDN
- K and c common
- k, Jka, Fya, Fyb, S, s, U
Hydrops fetalis
- Abnormal fluid buildup in 2+ compartments of baby organs
- sensitized RBCs undergo extravascular hemolysis (Rh incompatibility with mom)
Hydrops fetalis pathophysiology liver/spleen
- increased erythropoiesis-> erythroblastosis
- hepatosplenomegaly
- portal hypertension
- decreased albumin synthesis
Hydrops fetalis pathophysiology of plasma/heart
- decreased oncotic pressure
- high output cardiovascular failure
Hydrops fetalis pathophysiology of fetal tissues
edema, ascites, effusions
What are 3 ways to determine severity of hydrops fetalis in utero?
- ultrasonography
- amniocentesis
- cordocentesis
ultrasonography purpose
- measure amount of amniotic fluid
- determine size and location of placenta
- assess fetal edema, liver, and spleen size
amniocentesis purpose
- evaluate degree and significance of hemolysis
- determine change in OD450 of bilirubin
cordocentesis purpose
- venipuncture of umbilical vein
- determine H/H and bilirubin levels
Kernicterus
- excess maternal Ab still circulating in newborn
- RBC destruction continues
- Newborn liver limited ability to process indirect bilirubin
- rises dramatically to toxic levels->brain buildup
- bilirubin > 18 mg/dL
Why does jaundice appear in kernicterus?
- Bilirubin builds up in basal ganglia and cerebellum, which damages CNS
- within a few hr/day after birth
List ways of treating postpartum jaundice
- phototherapy for mild jaundice
- IVIG controls hemolysis action of Ab
- exchange transfusion for mod-severe jaundice, at risk of kernicterus (removes 90% Ab and 50% bilirubin)
How to select blood for neonate/fetus transfusion
- Group O or ABO compatible and Rh neg (O neg best)
- RBCs < 7 days old and suspended n Ab FFP
- CMV neg and leukoreduced
- Irradiated
- Hgb S-neg
- Ag neg for maternal Ab
Explain crossmatch for neonate/fetus transfusion
Crossmatch compatible with mom’s plasma or eluate made from baby’s sensitized RBCs
Baby’s cannot tolerate how much blood loss?
- > 10% blood loss
- maintain Hgb >14g/dL
Why are blood warmers required for neonate transfusion?
Hypothermia risk
Neonate/fetus transfusion risks
- graft v host disease due to immature immune system
- toxicity of K+, Ca+, H+ (liver can’t metabolize citrate, low GFR)
Describe exchange transfusion unit
- most often used for bilirubin removal, can be used to remove drugs or toxins
- double volume, 2 sep components that are 85 ml/kg
- FFP only used to suspend LRBC component to ideal Hct 45-60%
- fresh irradiation product is preferred to avoid potassium increase
