neonatal and ped transfusion 2
In a D− woman bearing D+ or D-unknown fetus what is the risk of developing anti-D with RhIg at 28 weeks and term?
0.1%
RhIG failure rate in patients receiving RhIg at 28 weeks and within 72h of delivery
0.1%
What is the frequency of rbc alloimmunization in the general population
0.2-2.5%
What is the procedural rate of fetal loss associated with cordocentesis?
1-2%
What is the onset of post transufsion purpura after transfusion?
1-24 days (average=9)
Platelet transfusion guidelines in neonates and older children with thrombocytopenia
1.Platelet count 5,000 to 10,000/μL with failure of platelet production. 2.Platelet count <30,000/μL in neonate with failure of platelet production. 3.Platelet count <50,000/μL in stable premature infant with: a.Active bleeding, or b. Before an invasive procedure with failure of platelet production. 4.Platelet count <100,000/μL in sick premature infant with: a.Active bleeding, or b. Before an invasive procedure in patient with DIC.
What is the estimated increase in K+ in the supernatant of an irradiated unit of rbcs after 2 days?
10 mmol/L
What is the frequency of antibody formation in a pt who is K neg after receiving 1 unit of K+ blood?
10%
What is the frequency of intracranial bleeding in patients with post transufsion purpura ?
10-15%
When does neonatal alloimmune neutropenia peak?
12 hours
Neonatal Alloimmune Thrombocytopenia (NATP)- incidence of fatal intracranial hemorrhage
12%
What is the critical titer for Anti-D?
16 or 32 in AHG or a difference of 2 dilutions
What is the frequency of rbc alloimmunization in patients with SCD?
18-47%
How frequent are intrauterine transfusions scheduled for severe HDN?
1st-2nd: 7-14 days; subsequent: 21-28 days
When does neonatal alloimmune neutropenia resolve?
2 to 4 weeks - 6m
Frequency of people who are HPA-1a (PLA1) negative in the general population
2%
At what age does full expression of ABH antigens occur?
2-4 years
Neonatal Alloimmune Thrombocytopenia (NATP)- incidence of intracranial hemorrhage overall
20%
What is the estimated increase in K+ in the supernatant of an irradiated unit of rbcs after 5 days?
20mmol/L
At what age are isoagglutinins detectable and when are they fully expressed?
3-5m and reach maximum titers at 5-10 years of age
Durationof Anti-D from RhIg
3-6 months
What is the frequency of autoantibodies in patients with SCD?
3-8%
What is the frequency of delayed hemolytic TFRX in patients with SCD?
4-22%
What is the frequency of HPA-1a alloimmunization?
5%
What percent of pregnant women are incompatible with their fetus' neutrophils?
5%
What is the frequency of rbc alloimmunization in patients with chronically transfused thalassemia?
5-11%
Neonatal Alloimmune Thrombocytopenia (NATP)- incidence of serious hemorrhage in utero
50% .
How much bilirubin is removed by exchange transfusion?
50% which then re-equilibrates between the intravascular and extravascular space
EPO dose
50U/ kg subq 3x/week
In a D− woman bearing D+ or D-unknown fetus what is the risk of developing anti-D without RhIg?
7-8% with the first pregnancy, 17% with subsequent pregnancies, 15-22% total lifetime risk
What is the chance that an Rh neg pt will form anti-D after receiving Rh+ blood?
75-90%
What is the critical titer for anti-Kell?
8 because Kell antigens are present on early red cell precursors
What is the risk of NAIT in subsequent pregnancies?
85-90%; this depends on the probability of inheriting the paternal allele
In infants of women with ITP- risk of severe thrombocytopenia (<50,000)
<10%
What is the frequency of neonatal alloimmune neutropenia?
<1:1000
How is the amount of K+ in the supernatant of a unit of irradiated rbcs calculated?
K+ conc in the supernatant x vol of the supernatant in the unit 25% in rbcs 40% in rbcs with no additive
The most common cause of severe HDN
Kell
What antigens are not expressed on cord red blood cells?
Lea, Leb, Sda, Ch, Rg, AnWj
At what point is intrauterine transfusion performed for HDN?
When the fetal Hct dec to <25-30%
ABO HDN is predominantly seen in mothers and fetuses with what blood types?
blood type O mothers bearing blood type A or B fetuses
Neonatal Alloimmune Thrombocytopenia (NATP)- cause
caused by maternal anti-platelet alloantibodies that cross the placenta and cause destruction of fetal platelet
Wra (WR1) and Wrb (WR2)
codominant pattern of inheritance and require an interaction with glycophorin A for expression
Neonatal Alloimmune Thrombocytopenia (NATP)- Neonatal platelet counts
commonly under 20,000
What are the transfusion goals and frequency for children with thalassemia
q 3-4 weeks to maintain a pre Hb of 9.5-10.5 and a post Hb of 13-13.5
Erythropoietin- use in children
renal disease
What is the duration of post transufsion purpura ?
resolves in 3 weeks
Why do antibodies to Kell antigens cause severe HDN?
they cause suppression of fetal erythropoiesis in addition to hemolysis
What antigens are expressed weakly on cord red blood cells?
A, B,I, H, P1, Lua, Lub, Yta, Xg, Sda
The most common type of HDN
ABO
How is severe neonatal alloimmune neutropenia treated?
An ANC <500 is treated with G-CSF
what antibody is suspected in a woman whose serum contains anti-D and anti-C despite having received appropriate RhIG prophylaxis?
Anti-G
Second most common cause of severe HDN
Anti-c, then Fya
How is exchange transfusion of an infant performed?
Approximately 2x the infant's TBV is given while the infants blood is removed over 1-2hours
Distinguishing bile pigments from hemoglobin during amniotic fluid spectrophotometric analysis
Bile pigments, oxyHb and meconium: absorbance at 450nm; Hb absorbs at 410nm and 450nm. To correct for the contribution of Hb absorption, the delta OD410 is calculated, x 0.05 and subtracted from delta OD450 to give the corrected OD 450. Multiplying the absorption at 450 by 0.05% accounts for the fatc that absorption at 450 is only 5% of that at 410.
Wra antibody- common findings
Commonly found in pts with hyperactive immune systems who are exposed to Wra+ cells. Commonly seen in the sera of: recently delivered women who have formed anti-D, pts with AIHA, pts alloimmunized to the other blood group antigens
What is an adverse effect of EPO
antibodies causes red cell aplasia
What is the relative immunogenicity of protein blood group antigens?
D>K>c>E>e>Fya>C>Jka>S>JKb>s
What D antigen type is the most significant partial D?
DVI
At what point is neonatal exchange transfusion performed?
Decisions are guided by gestational age, bilirubin conc, rate of bili increase (>0.5mg/dL/hour) and other comorbid factors
What are the target antigens in neonatal alloimmune neutropenia?
HNA-1a, HNA-1b, HNA2a
Neonatal Alloimmune Thrombocytopenia (NATP)- most common target platelet antigen
HPA-1a (PLA1)
What is the most common cause of NAIT in Asian patients?
HPA-4A (Yuk/ Pena)
Neonatal Alloimmune Thrombocytopenia (NATP)- less common targets
HPA-5b (10%), HPA 1b(4%), HPA 3a(2%)
Why is the rate of HPA1a alloimmunization so low ?
HPA1a antibodies has been only found in patients with the HLA DRB3*01 gene and the HLAR52a or HLA A1B8DR3 haplotypes
What platelet antibodies are more common in women of african ancestry?
HPA2 (Ko) or HPA5 (Br)
When investigating for HDN, what antibodies can be ignored whether IgG or IgM and why?
I, P1, Lea, Leb; these antigens are poorly developed at birth
ABO HDN- cause of hemolysis
IgG anti-A, B antibody
Which antibody class is transported accorss the placenta earlier and in larger amounts in Hemolytic disease of the newborn?
IgG1
Women with what type of IgG anti-HPA 1a have more severely affected infants?
IgG1
Which IgG subclasses are more efficient at causing hemolysis?
IgG1 and IgG3
Hemolytic disease of the newborn - maternal alloantibody class
IgG1, IgG3, or IgG4 class
Features that suggest active alloimmunization and not passive anti-D from RhIg
IgM anti-D, titer >4 and persistence of antibody 3+ months after administration
Why is it important that IM RhIG not be given by IV?
It contains aggregates of Ig that may activate complement.
At what point is immediate exchange transfusion recommended?
It the infant shows signs of acute bilirubin encephalopathy (hypotonia, arching, fever, high pitched cry) or if T bili is >= 25mg/dL
Are antibody titer predictive of HDFN in women who have had affected fetuses?
No.
What is the target antigen in post transufsion purpura ?
Platelet antigens- HPA-1a
What antigens are expressed strongly on cord red blood cells?
Rh, K, Fy, Jk, MNSs, Di, Do, Sc, Coa, Aua,i i think that our (Rh), Kidds, Duffy, Diego, Dombrock, Colton and Scianna are menaces to the umbilical cord
Why may the D type on cord blood be falsely negative?
The cells may be heavily coated with anti-D- "Blocked D"; do an eluate
Maternal Immune Thrombocytopenic Purpura (ITP)
The immune-mediated destruction of platelets, usually on the basis of autoantibodies directed against platelet surface antigens such as HPA-1a (PLA1).
How are the # of vials of RhIg to be given determined?
You have to round up to the nearest integer if the number after the decimal is <5, and up two integers if >5
What is the clinical presentation of post transufsion purpura ?
abrupt thrombocytopenia (<10,000); pt also destroys own non antigenic platelets
Guidelines for transfusion of rbcs in pts >4mo
acute blood loss >15% TBV; hb <7g/dL with symptomatic anemia; sig preop anemia when other corr therapy is not available; hb <13 on ECMO; chronic TF for disorders of rbc prod
How does the fetal MCV of rbcs compare with maternal MCV?
fetal MCV is usually ~ 114fL. This can be used for rapid confirmation that fetal blood has been sampled during cordocentesis. This distinction is decreased later in pg and after the first IUT
Wrb (WR2)- prevalence
high prevalence- frequency of 99%
What are the complications of neonatal exchange transfusion?
hypocalcemia, apnea, cyanosis, vol overload, hyperK+, air emboli, vasospasm, thrombosis of umbilical vein, NEC, infection
What test result is predictive of fetal anemia?
increased middle cerebral artery peak velocity
What is the immunizing stimulus of NAIT in the first pregnancy?
inflammation in the chorionic villi
In infants of women with ITP-risk of serious hemorrhage
intracranial hemorrhage in <1%, confined to neonates with platelets less than 20,000
What less common antibodies cause moderate or severe HDN?
k, Kpa, Kpb, Ku, Jsa, Jsb, Jka, Fyb, M, U
What is the nature of the NAIT caused by antibodies to HPA-5b?
less severe- mild thrombocytopenia
Wra (WR1) prevalence
low prevalence- frequency of 0.001%
EPO dose in premature infants
metabolized it faster and thus need increased doses: 200-400U/kg 3x/ week
In what population does post transfusion purpura most commonly occur?
multiparous females
At what point in the pregnancy is intrauterine transfusion typically done if indicated?
not before 20 weeks or after 35 weeks
What can be given to the mother 7-10 days after the last intrauterine transfusion to enhance fetal hepatic maturity and decrease the need for neonatal transfusion?
phenobarbital
The risk of neonatal thrombocytopenia in Maternal Immune Thrombocytopenic Purpura (ITP) is highest with
previous maternal splenectomy for ITP, previous infant with ITP, & gestational (maternal) platelet count <100,000. It is recommended that serial neonatal platelet counts be monitored for a few days after delivery.
The rosette test
uses D+ indicator cells to form rosettes around D+ fetal cells. It will detect as little as 10cc of fetal blood. The results are qualitative. If this test is positive, then a Kleihauer-Betke or ELAT is indicated.
How can anti-G specificity be confirmed?
using rGr (D-C-G+) cells and DIIIb (D+C-G-) cells
RBC washing
washed in sterile saline. removes 98% of the plasma
In the event of fetal-maternal hemorrhage of unknown quantity due to ectopic pregnancy, amniocentesis, chorionic villus sampling, spontaneous abortion, etc, then what are the RhIG requirements in a D− woman bearing D+ or D-unknown fetus?
within the first 12 weeks of gestation, a small vial (50 μg) dose is given; after 12 weeks, a full dose (300 μg) vial is given
