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