HDFN Flashcards

1
Q

Anti-K HDFN

A

affects Kell positive precursors in the bone marrow, suppresses rather than hemolytic destroys precursors. Lab results low bilirubin and reticulocytopenia

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2
Q

HDN etiologies

A

hemolytic disease of newborn: infection, RBC membrane defects, hemolysis due to blood group incompatibility

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3
Q

Most efficient antibody in crossing the placenta

A

IgG1 (IgG3 and IgG4 also efficient) IgG2 cannot cross

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4
Q

Important considerations of fetal antigen

A

homozygous vs. heterozygous, degree of antigen expression, could affect the severity

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5
Q

Erythroblastosis fetalis

A

Anemia, depends on the ability of the fetus to increase hematopoiesis- this causes hepatosplenomegaly. causes portal hypertension and leads to hydrops fetalis

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6
Q

What occurs in system during hydrops fetalis

A

portal hypertension, edema, effusions, cardiac failure (minimum excess bilirubin-hyperbilirubinemia is not the issue)

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7
Q

Steps of hemoglobin breakdown in fetal/maternal situation

A

hemoglobin can take one of two routes: it always goes to unconjugated bilirubin, which can then go to the placenta, then to the mothers liver, is broken down to conjugated and excreted by the mother. The unconjugated bilirubin can alternatively go to the immature fetal liver which can’t break it down and it is continued as toxic unconjugated bilirubin- leads to hyperbilirubinemia, jaundice and kernicterus

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8
Q

kernicturus

A

nuclear jaundice- bilirubin deposits basal ganglia which interferes with mitochondrial function. Bilirubin builds up in babies brain

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9
Q

Quantity of billirubin in kernicturus

A

> 25mg/dl normal 8-12 mg/dl VLBW (very low birth weight)

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10
Q

outcome of kernicterus

A

high morbidity and mortality

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11
Q

How much blood is needed to cause immunization

A

0.1 mL of fetal blood

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12
Q

outcome of RHHDN

A

historically very severe anemia and death in utero- through use of RHIG significantly reduced

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13
Q

How does ABO incompatility offer protection against alloimmunization

A

16% vs. 1.5-2%

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14
Q

ABO HDFN hemolysis

A

usually mild, requiring no treatment, only in O mothers due to ABO antibodies being both IgM and IgG

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15
Q

Prenatal testing performed

A

ABORH Ab screen, weak D not required. Antibodies ignore: I, P1, Lea, Leb. Testing father for “offending” antigen

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16
Q

Father testing in prenatal studies

A

Test for antigen, if it’s heterozygous 50/50 chance child received it homo 100% chance child got it. Consider DNA testing if anti-D in mother

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17
Q

Genotyping fetus methods of collection

A

Amniocentesis, p.b. of mom, CVS (chorionic villus sampling), Cordocentesis

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18
Q

CVS

A

chorionic villus sampling, collecting from placenta where attached to uterine wall

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19
Q

Cordocentesis

A

PUBS- percutaneous umbilical blood sampling, use ultrasound to find appopriate placement

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20
Q

Syndromes affecting pregnant women involving blood transfusion

A

ITP (idiopathic thrombocytopenia) HDFN, FNAIT (fetal and neonatal alloimmune thrombocytopenia)

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21
Q

Earliest HDFN can occur

A

18-20 weeks

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22
Q

Half life if IgG

A

21-25 days

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23
Q

Titer considered significant in prenatal testin

A

> /= 16 or 32. exception is anti-K significant >/=8. There is no need to titer ABO or IgM antibodies

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24
Q

How do you test samples that have been frozen for titers

A

in duplicate

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25
Q

Doppler ultrasound

A

non invasive monitoring, measures the blood flow of MCA, increase blood flow indicated anemia- transfusion should be considered, assess hydrops fetalis

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26
Q

MCA

A

middle cerebral artery

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27
Q

Delta OD

A

change in the optical density, bilirubin present in the amniotic fluid makes it yellow and changes the optical density. Run the sample to determine OD, a linear downward line charted- compare the result read at 450 with the graph line and document the change, this is the change in the optical density

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28
Q

Reading the results of optical density

A

0.26-0.46 low risk (zone 1) 0.47-0.90 middle risk (zone 2) 0.91-1.0 High risk (zone 3)

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29
Q

IUT

A

intrauterine transfusion blood selection: irradiated hgbS negative, CMV- reduced risk, “fresh blood” antigen negative (consider using mom) compatible with mom’s plasma

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30
Q

Facts about IUT

A

hct decline 1% per day, usually required within 1-2 weeks, holds of hematopoiesis therefore holding of erythroblastosis fetalis, maintain until delivery

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31
Q

Other alternatives to IUT

A

mother plasma exchange-reduces anibody temporarily, IVIG

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32
Q

infant testing at birth

A

aborh (no reverse), perform weak D testing be aware of “Blocked D” phenomenon

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33
Q

DAT infant testing

A

may be positive with RHIG, may be negative with ABO HDN, if DAT+ and mom’s ab screen is negative, consider low incidence antigen.

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34
Q

Good source for antigen negative blood for baby for IUT

A

mother’s blood

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35
Q

Treatment goals HDN

A

prevent complication from hyperbilirubinemia (phototherapy and exchange transfusion) treat anemia (straight transfusion or exchange transfusion)

36
Q

RBC requirements for transfusion of neonates

A

IRRadiated if <1200g. standard dose for transfusion is 10-15ml/KG

37
Q

Objectives of exchange transfusion

A

reduce billirubin, reduce maternal antibody, correct for anemia

38
Q

How much is in one vial of Rhogam and how much does it cover

A

1ml (300ug) clears 30ml of WB or 15mL of RBCs

39
Q

Rosette test

A

Qualitative, detects FMH >/=10mL. infant cannot be weak D positive,must be D positive. Mother being weak D positive invalidates results

40
Q

Kleihauer Betke

A

quantitative (kind of) poor precision and accuracy. Acid elution test- capitalizing on resistance of fetal hgb to acid treatment. Mom blood put on a slide, acid treated, rinsed and counterstained. Count 1000-2000 cells. maternal cells are “ghost cells” fetal cells are pink

41
Q

Problems causing erroneous results with KB test

A

hereditary persistence of fetal hemoglobin disease in mother, sickle cell disease

42
Q

Calculation of FMH from KB test

A

(Fetal cells counted/total cells counted) x mothers blood volume (5000mL typically used)

43
Q

3 ways to detect FMH

A

KB, rosette test, flow cytometry

44
Q

Positive and negative rosette test

A

negative and = 4 rosettes per 5 fields is negative (less than 30mLs) anything more than that is positive

45
Q

Additional indications for RHIG

A

PUBS, Amniocentesis, miscarriage/abortion, CVS, ectopic pregnancy, antepartum bleeding (abdominal trauma, placental abruption, threatened abortion) any other condition that would be a risk of fetal RBCs entering mothers circulation

46
Q

Alloimmune thrombocytopenia

A

most common antibody implicated is anti-HPA-1a, antigen present in 98% of population, can affect first pregnancy not known until delivery- potential of intracranial hemorrhage

47
Q

Treatment for mom in future pregnancies

A

determine fetal DNA genotype, IVIG for mom, transfuse HPA-1a negative platelets (can use mom, however must be washed (due to antibody))

48
Q

VLBW

A

very low birth weight

49
Q

which tends to be more severe: thrombocytopenia from SLE or from ITP (maternal)

A

ITP

50
Q

Volume of fetal cells calculation

A

(#fetal cells/#of maternal cells)(5000mL) = mL of fetal blood

51
Q

Prenatal titers saline AHG vs. albumin

A

recommendation is saline AHG, albumin AHG (or gel) results typically in higher titers.

52
Q

Most common types of ABO-HDFN

A

European ancestry and asians- Type A babies type O moms, Blacks- Type B babies type O moms

53
Q

High MCA result

A

> 1.5 MoM (multiples of the mean) indicates moderate to severe anemia

54
Q

Why does it need to be HGbS negative

A

prevent sicking under low oxygen tension

55
Q

typical hematocrit of concentrated RBC unit requested for neonates

A

70-85%

56
Q

what do you need to do if using mother’s blood for IUT

A

wash and irradiate

57
Q

calculation volume of blood to be transfused

A

(estimated fetal weight (g) multiplied by 0.14mL standard factor) x (goal hct-current hct) / (hct of the rbc unit to be transfused)

58
Q

Where is the IUT transfused into

A

umbilical cord artery

59
Q

second choice for location of IUT

A

peritoneal cavity

60
Q

what does IVIG treatment do in mother with antibody (HDFN)

A

stabilized anti-D titers- best if used before 28 weeks

61
Q

What does plasma exchange of mother with anti-D do?

A

Drops antibody levels by 75%

62
Q

What does phototherapy do?

A

Oxidizes unconjugated bilirubin allows for release from system

63
Q

How is RHIG made?

A

human pooled plasma from individuals naturally immunized or intentionally immunized.

64
Q

Chance of an RH mother being immunized to Rh

A

16%

65
Q

Chance of an RH mother being immunized to Rh after administration of RHIG

A

<0.1%

66
Q

Relevance of anti-G in pregnancy

A

it’s important to differentiate anti-G from anti-D and anti-C, if anti-G is present mother still gets RHIG, if they are immunized to Rh with anti-D present, they don’t receive RHIG

67
Q

RHIGs role in vivo

A

D pos RBC- opsonized by the RHIG IgG cleared by macrophages in the spleen

68
Q

Weak D

A

european ancestry most common types 1,2,3 don’t need RHIG any other type of weak D should be given RHIG and considered D negative due to lack of understanding about other weak D types to become alloimmunized.

69
Q

Risks of IUT

A

Donor blood further alloimmunization of the mother to new antigens. Providing RBC matched: Rh, K Fy, Jk, S- decreases immunization by 60%. You can use mother’s blood but it must be washed.

70
Q

FNAIT antibodies cause.

A

Fetal, neonatal alloimmune thrombocytopenia. 80% of european cases caused by anti-HPA-1a antibody. (HPA-1a present in 98% of population). 10% Anti-HPA-5b 4% Ant-HPA-2b 2% Anti-Hpa-3a. In asians anti-HPA-4b is the most common

71
Q

Signs and symptoms of FNAIT in babies

A

GI bleeding, petechiae, ecchymoses, ICH

72
Q

Treatment/Prevention of FNAIT

A

IVIG administration in mom- effective in nearly 100% (success is measured by absence of ICH)

73
Q

ITP in neonates

A

immune thrombocytopenia. Baby may be thrombocytopenic if mother has ITP or SLE- antibodies cross the placenta and cause the same problems in the baby as they did in the mom, once the maternal antibodies are gone the platelet count should go back to normal

74
Q

Sequalae

A

any abnormality following a disease or treatment or surgery

75
Q

Which is more severe ITP or FNAIT?

A

FNAIT is much more severe. In ITP only 0-1.5% ICH, even less severe if due to maternal SLE than ITP

76
Q

Treatment of ITP in neonates

A

IVIG, corticosteroids for mom. In baby: ultrasound of brain looking for ICH - if life threatening hemorrhage should be treated with platelets and maybe IVIG/steroids

77
Q

What is a VLBW baby

A

<1500g

78
Q

Extremely low birth baby

A

<1000g

79
Q

Premature baby hgb compared to full term neonate

A

premature= 1 g/dL lower hgb than normal; Hgb usually drops following birth post birth drops to 8/7 g/dL

80
Q

Why does Hgb drop in baby (3 reasons)

A
  1. EPO decrease (prolonged in premature babies) -decreased RBC production 2. Decreased survival of fetal cells 3.Increasing blood volume due to rapid growth. decrease EPO, increase 2,3 DPG, PO2 and HgbA.
81
Q

EPO production- where does it take place

A

Originally liver production of EPO, however once born it switches to kidney based production of EPO

82
Q

AABB standars for how frequently to test babies blood type

A

Due to infants inability to make antibodies, no repeat of ABORH or ABscreen testing needs to be done during the initial 4 month period of the baby in hospital.

83
Q

ECMO

A

extracorporeal membrane oxygenation. a machine that removes blood from patients venous ciruclation, the blood is circulated through a machine that removes CO2 and replaces O2 and then is returned to the patient.

84
Q

Necrotizing entercolitis

A

ischemic necrosis of intestinal mucosal associated with inflammation, invasion of enteric gas forming organisms and dissection of gas into abdominal cavity

85
Q

SCI

A

silent cerebral infarcts;

86
Q

ECMO and platelets

A

ECMO circuit consumes platelets higher platelet counts are maintained.

87
Q

what is the least invasive method for retrieval of fetal cells for genetic testing

A

probably mother’s p.b. with free floating baby DNA, however if not at a high enough quantity amniocentesis is the next option (cell-free fetal DNA typically at high enough quantity at 15 weeks)