Flashcards in 11.6: Transfusion II Deck (40):
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?
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?
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?
- Baby with HDN cant form clots
Symptoms of fetus with HDN?
- 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?
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?
- 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
- Activate complement pathway
Danger or warm autoantibodies?
- Cause cross matching compatibility with all RBCs
Disease associated with unexpected autoantibodies?
1. Systemic Lupus Erythematosus
2. Chronic lymphocytic leukemia
3, Normally idiopathic
Markers of immune hemolysis?
1. Falling hemoglobin and hematocrit
3. Elevated LDL
4. Positive DAT /IAT
5. Low haptoglobin
Clinical findings in anemia?
- Exercise intolerance
Treatment of warm hemolytic anemia?
2. IV gammaglobulin
3. RBC transfusion: safe as long as on steroids
- Even if cross math is incompatible
Unique symptoms for cold agglutinin disease?1
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
Which hemolytic anemias associated with positive DAT?