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blood bank sem 2 > HDFN > Flashcards

HDFN Flashcards

1
Q

HDFN

A

destruction of RBC’s of the fetus or neonate by maternal antibodies

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2
Q

IgG can cross the placenta by

A

active transport

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3
Q

most dangerous IgG

A

IgG1 and IgG3

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4
Q

2 most common types of HDFN caused by

A

Rh antibodies and ABO antibodies

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5
Q

as little as _____ of fetal RBCs are enough to stimulate formation of Anti- D

A

1 mL

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6
Q

most antigenic antigen in Rh system

A

D

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7
Q

does the titer matter when to comes to Kell

A

no any titer is dangerous

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8
Q

HDFN antibodies almost never a risk

A

Anti- Lea
Anti- P1
Anti- I
Anti- U

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9
Q

how to limit sensitization to D antigen

A

give D - blood to D- women

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10
Q

antigen matching aside from D has proven ineffective at preventing severe HDFN why?

A

pregnancy is much more common than transfusion

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11
Q

IgG causes hemolysis of fetal RBC’s and what destroys IgG tagged cells

A

Fetal reticuloendothelial system

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12
Q

when the fetus becomes anemic the marrow compensates and this can lead to

A

erythroblastosis fetalis

-erythroblasts in fetal circulation (young nucleated red cells)

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13
Q

when fetus is anemic is anemic what organs affected

A

spleen and liver enlarged

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14
Q

hydrops fetalis

A

used to be fatal, now not

caused by anemia and hypoproteinemia

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15
Q

when rbc are lysed the Hgb released is metabolized to

A

indirect (unconjugated) bilirubin

BILIRUBIn does not cause a problem for the fetus because it crossed placenta and mother clears it

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16
Q

Anti-D half life

A

25 days

so RBC destruction still happens after birth

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17
Q

can neonates effectively conjugate bili

A

no they can’t because they can not excrete it = janudice

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18
Q

toxic amount of bili in baby

A

18-20

normal = 1

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19
Q

bili buildup in baby called

A

kernicterus
include= seizures, poor feeding, visual damage, cerebral palsy

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20
Q

prenatal testing for mother

A

type and screen- 1st tri

if mom is D- and screen is neg= she can get RhIG

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21
Q

if prenatal screen is positive tech must

A

Antibody ID

if anti-D present find out if true immune or given rhogam

(passive is if previously had Rhogam)

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22
Q

if a mother has true immune anti-D, paternal testing is ordered. baby has to be Rh - if father is

A

homozygous for antigen

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23
Q

baby may be Rh- if father is

A

heterozygous

-testing can be done to see if baby inherited antigen
(amniotic fluid)

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24
Q

what test can be done to determine if baby is Rh -

A

Cell free fatal DNA testing

PCR run on mom plasma which contains fetal DNA detectable at 7 weeks

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25
what is amniocentesis
extraction of portion of amniotic fluid and can measure extent of HDFN, see specific antigen, access lung maturity
26
what can cause FMH
amniocentesis risk of sensitizing mother to fetal antigen if a bleed is causes
27
when is amniocentesis done
27-40 weeks
28
if true immune anti-D physician may order
titration FMH and follow up only performed on D-negative patients
29
fetomaternal hemorrhage screen
has fetal blood crossed maternal circulation
30
Kleihauer-Betke
ordered if FMH screen is positive determines how much fetal blood in maternal circulation
31
what happens in antibody titration
2 fold serial dilution of maternal plasma -tests against RBCs that are homozygous for the specific antigen IAT express titer as reciprocal of highest dilution only run on specific antibody!!
32
agglutination scores
4+ = 12 3+ = 10 2+ = 8 1+ = 5
33
if titer increases during pregnancy
fetus should be presumed to be antigen + (mom's immune system having secondary response) consider intrauterine exchange
34
RhIG titer should never be over
4
35
if titer >8 a second titer needs to be done at
18-20 weeks run in parallel with previous titer
36
if titer greater than 16
fetus will need middle cerebral artery peak systolic velocity
37
if titer is 16 or less it needs to be measured every
2-4 weeks from 2nd tri on
38
if titer consistently less than 16
lower risk except for KELL (titer doesn't determine severity for KELL)
39
Anti-D binds
D-positive fetal cells and removed from circulation do not sensitize the mother to D antigen
40
indications for RhIG
Rh - patient 10-28 weeks gestation if type and screen negative within 72 hours of birth abdominal trauma amniocentesis spontaneous/ induced abortion
41
one dose of RhIG removes
30 mL of fetal blood in circulation
42
post partum testing cord blood
group O and Rh- mothers need newborn's type determind Rh - mothers with Rh + baby with negative screen / passive anti-D mom will get 1 dose of RhIG
43
after mother gets another dose of RhIG after birth they need
fetomaternal hemorrhage screen negative- no more RhIG Positive quantify blood
44
if FMH is +
blood be quantified to determine additional RhIG needed
45
RhIG dose calculation
#Doses = Volume FMH/30 +1
46
volume of FMH =
%fetal cells in maternal circulation x 5000 mL
47
specimen for testing for newborns
cord blood is typical specimen- heelstick if necessary
48
ABO/Rh on newborns
forward typing no back type or else mothers cause no antibodies may see weaker reactions weak D done on all D- infants
49
why weak D testing on infant
mother could still make antibodies to D antigen from baby
50
DAT newborns
washing important looking got IgG Rh antibodies aren't effective at fixing complement
51
newborns elution
if DAT is positive -antibody from mom if mom type and screen negative - could be antibody to uncommon blood group
52
if newborn DAT positive what is monitored
serum bili CBC show evidence of anemia spherocytes nRBCs polychromasia
53
most common cause of HDFN
ABO since RhIG happened usually anti-A,B naturally occuring
54
small amount of anti-A and anti-B are
IgG these can cross the placenta and hemolyze fetal cells
55
testing for newborns
front type fetal cells ABO, DAT, elute antibody and ID antibody
56
who are protected from sensitization from D antigen
mothers incompatible with fetal RBC's for both ABO and D ABO incompatible cells are destroyed in maternal circulation before anti-D can be formed
57
treatment of HDFN
intrauterine transfusion exchange transfusion induction phototherapy
58
normal Hgb for newborn
14-20
59
intrauterine transfusion
inject pedi-pak directly into umbilical vein goal: maintain Hgb > 10 may need to repeat every 2-4 weeks until delivery
60
indications for intrauterine transfusion
Middle cerebral artery-peak systolic velocity suggest anemia cordocentesis < Hgb 10 amniocentesis elevated bili hydrops fetalis
61
exchange transfusion
replace newborn's circulation blood pre and postpartum goal: improve Hgb level to treat anemia, reduce hemolysis to prevent bili
62
who is most likely to need an exchange transfusion
premature neonates liver and kidneys less developed than full term removes antigen + cells, bili
63
AABB recommends giving
ABO matched units
64
zone 1 liley graph
low risk
65
liley graph zone 2
moderate
66
liley graph zone 3
high risk need intervention more bili= more dangerous
67
liley graph detects
amount of bili present in amniotic fluid
68
induction
possible option if fetus is in high risk group of Liley graph at 32 weeks or later
69
lecithin/sphingomyelin ration over
2:1 indicates sufficient lung maturity
70
what may require exchange transfusion after birth
induction better to deliver and than transfuse
71
what light is best for phototherapy
490 nm cuts bili half life by 50%
72
how does phototherapy work
light isomerizes unconjugated bili and makes it water soluble and can be excreted by neonate

blood bank sem 2 (6 decks)

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