11.6: Transfusion II Flashcards
WHat is HDN?
“Hemolytic disease of the newborn”
- Hemolytic process in perinatal period resulting in abnormal RBC production
What is the perinatal period?
The time during pregnancy
Main cause of HDN?
- Unexpected alloantibodies
- These are not ABO antibodies
- Most are IgG and do not bind complement
- Associated with delayed, extravascular hemolysis
What detects alloantibodies?
Antibody screen
Why does HDN occur?
- Fetus inherits half of paternal RBC antigens
- Fetal RBC passes transplacentally into mother
- Mother produces IgG against fetal antigens that she does not share
- IgG can freely cross placenta
Which antibodies freely cross into fetal circulation?
- IgG
Normal progress in HDN?
- 1st pregnancy mother RH-, fetus RH+
- Pregnancy goes fine but mother now sensitized
- 2nd pregnancy, maternal antibodies cross placenta to attack RH + newborn
What is an FMH?
“Fetal maternal hemorrhage”
- Incidence allowing fetal RBCs to cross placenta to mother
- Risk increases w/ gestational age: highest risk at pregnancy
What is erythroblastosis fetalis?
- What happens to baby in HDN
- Peripheral smear of baby showed nucleated RBCs and erythroblasts
- Not normally found in marrow
What are erythroblasts?
- RBC precursors
What is another name for RH factor?
- Anti D
- D positive fetus’ mother makes anti D
- Fetus RBCs are thus sensitized and will agglutinate in antiglobulin test
Where do fetus’s make RBCs>
- Liver and spleen
- Not in marrow until born
- Thus HDN babies demonstrate hepatosplenomegaly with liver failure
Where are coag factors made?
- Liiver
- Baby with HDN cant form clots
Symptoms of fetus with HDN?
- Hepatosplenomegaly
- Decreased coagulation and platelets
- Lowe liver function
- Shortened RBC life
- Hypoalbuminemia, leading to edema / hypotension and CHF
- Jaundice / hyperbilirubinemia
- High risk of kernicterus and neurologic damage
What is anasarca?
- Whole body edema
HDN IV or EV?
Extravascular
What is kernicterus?
- Staining of basal ganglia due to severe hyperbilirubinemia
- Causes neuronal damage
When does HDN occur with isoagglutinins?
THIS WILL BE ON EXAM*
- Normally when mother is “O” so has anti A/B/AB
- DAT will be positive
- Disease is usually milder
What usually causes HDN?
- D antigen of RH blood group
- This is only type we have prophylaxis for
How do we prophylaxis for HDN?
- Give mother protein concentrate of anti D: “RH immune globulin”
- This prevents mothers from making own alloantibodies
- Given at delivery and at 28 and 30 weeks
- We do not know how it works but it does
What happens when mother is already sensitized and makes anti D?
- Pregnancy is high risk and taken care of specialists
What is amniotic fluid made of?
- Fetal urine
Old way of monitoring high risk sensitized mother?
- “Ultrasound guided amniocentesis”
- Sample amniotic fluid with needle and US
New way of monitoring fetus for HDN?
- Ultra sound monitoring of cerebral blood flow for kinetics
- Anemic blood flows faster so we can test for anemia
- If anemia, intrauterine transfusion needed into umbilical vein while in placenta
- Monitor bilirubin once born
How to treat baby with high bilirubin?
“Bili lights”
- Phototherapy with UV lights
- Solubilize unconjugated bilirubin
- Urobilinogen then excreted in kidneys
- **If lights don’t work exchange transfusion performed
What is bilirubin?
- Yellow breakdown product of normal heme catabolism, caused by clearance of aged RBCs which contain hemoglobin
- Bilirubin is excreted in bile and urine
- Elevated levels may indicate certain disease
What are cold and warm antibodies?
Cold: dont work at body temp so inconsequential
Warm: React at body temp
***Both are non specific and directed against RBC membrane antigens
How do you dectect autoantibodies?
AIT: antibody screen
Which autoantibodies cause most trouble?
- Warm, IgG in nature cant coat RBC or be in plasma
- Will cause positive DAT or IAT
Characteristic of cold autoantibodies?
- Usually silent and don’t cause problems
- IgM
- Activate complement pathway
Danger or warm autoantibodies?
- Cause cross matching compatibility with all RBCs
Disease associated with unexpected autoantibodies?
- Systemic Lupus Erythematosus
- Chronic lymphocytic leukemia
3, Normally idiopathic
Markers of immune hemolysis?
- Falling hemoglobin and hematocrit
- Hyperbilirubinemia
- Elevated LDL
- Positive DAT /IAT
- Low haptoglobin
- Spherocytes
Clinical findings in anemia?
- Fatigue
- Exercise intolerance
- Weakness
- Pallor
Treatment of warm hemolytic anemia?
- Corticosteroids
- IV gammaglobulin
- RBC transfusion: safe as long as on steroids
- Even if cross math is incompatible
Unique symptoms for cold agglutinin disease?1
- Acrocyanosis when cold
What is acrocyanosis?
- Bluish or purple coloring of the hands, lips and feet caused by slow circulation
How to treat ptn. with cold agglutinin disease?
- Keep warm
- Prednisone
Which hemolytic anemias associated with positive DAT?
- All
Is Igm see on RBC in cold autoimmunity?
No only complement
