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Liz's Blood Bank Module 2 > HDFN > Flashcards

Flashcards in HDFN Deck (55):
1

List the 3 classes of HDFN

- ABO HDFN
- Rh HDFN
- "Other" HDFN

2

Msot common class of HDFN

ABO HDFN

3

Most severe class of HDFN

Rh HDFN

4

Mechanism of maternal immunization and placental transfer of Ab(s) in HDFN

When baby is born, the placenta breaks and there's a disruptio of placental circulation and an exchange of maternal and baby blood. The mother makes Abs to the foreign cells

5

Most common ABO group of a mother who delivers a newborn affected w/ ABO HDFN

Group O

6

List 3 reasons that a first born child is more likely to be affected w/ ABO HDFN than Rh HDFN

- ABH Ags found widely distributed throughout body
- ABH Ags aren't fully developed in fetal life
- IgG titer of ABO Abs is usually much lower than anti-D b/c most ABO Abs are IgM; less cross placental and less damage to cells

7

3 reasons for the severity of Rh HDFN

- Rh is only found on RBCs
- Rh Ags are fully developed at birth
- IgG titer is higher b/c it crosses the placenta

8

Reasons for the severity of "Other" HDFN

?

9

Reasons for the severity of ABO HDFN

?

10

3 reasons why ABO HDFN is usually a relatively mild disease

?

11

How can fetomaternal ABO incompatibility prevent immunization of the mother against Rh or other blood group Ag

In ABO-incompatible pregnancies, the baby's RBCs are IMMEDIATELY sensitized by the mother's ABO abs and are quickly removed from her circulation by her liver

12

HDFN
- Mechanism of RBC destruction by maternal Ab

Abs are produced as a result of txn or pregnancy. The exposure is usually at the time of the delivery

13

HDFN
- Response of fetus to RBC destruction

Anemia

14

HDFN
- Management of bilirubin in utero

Baby's cells become coated in utero, cells removed by baby's RES, Hgb breaks down, indirect bili produced, bili removed by moms liver before birth

15

HDFN
- Management of bilirubin after delivery

After birth, baby's immature liver canot conjugate bilirubin, so it accumulates in the baby's system → kernicterus

16

HDFN
- Greatest danger to the fetus in utero

?

17

HDFN
- Greatest danger to the newborn after delivery

?

18

List 3 indications for performing intrauterine txns (IUTs)

- Amniotic fluid graphs in high zone II or in zone III
- PUBS indicates hgb level < 10 g/dL
- Fetal hydrops is noted on ultrasound exam

19

What type fo blood should be selected for IUT?

- O neg,
- Washed cells with >80% HCT
- Compatible with mom's serum
- Ag Neg to mom's Ab
- "Fresh"
- Irradiated, leukoreduced
- CMV, hgbS Neg

20

At birth, baby's blood type may look like ____ ____ b/c 90% of circulation is transfused cells. ____ at birth may be mixed field positive, or possible negative

O negative; DAT

21

Criteria for cord blood work-up

- Group O
- Rh negative
- IAT +

22

Cord blood work up
- Weak DAT +

ABO HDFN

23

Cord blood work up
- Strong DAT +

Rh HDFN

24

Elution is performed on cord blood to identify ____ coating cell

Ab

25

HDFN is characterized by what?

Ags absent on maternal RBCs, but present on paternal RBCs

26

The Ab involved in HDFN can be transported across the placenta b/c it belongs to which Ig class?

IgG

27

Discuss the pathogenesis of HDFN

- Mother lacks Ag; father has Ag
- Fetus has Ag
- Mom makes Ab after fetomaternal bleed
- Ab crosses placenta in subsequent pregnancies
- Ab coats fetal RBCs

28

Total bilirubin in the fetal circulation and amniotic fluid may be elevated in HDFN but why is the fetus NOT affected?

Bilirubin gets filtered out by mom's liver

29

Which statement is true for ABO HDFN?
- a) It's generally milder than Rh HDFN
- b) It does not occur in a first pregnancy
- c) The mother is usually blood group O
- d) Phototherapy is often the only treatment required

It doesn't occur in a first pregnancy

30

If a neonate requires an exchange txn for HDFN, why is the maternal specimen is the specimen of choice to use for the compatibility test? 2nd choice? 3rd choice?

- 1st: Mom's serum has highest concentration of offending Ab and therefore, the best sample to test w/
- 2nd: Eluate made from baby's cells
- 3rd: Baby's serum

31

Principle of Liley graph

Plots change in optical density vs. gestational age. Amniotic fluid is measured at 450nm to detect amounts of bilirubin present. Result is plotted and point falls into 1 of 3 zones

32

Define zones I, II, and III on the Liley graph

- Zones I → mild or no disease
- Zones II → moderate; continue to monitor throughout pregnancy
- Zones III → severe disease, hemolysis; IUT or early delivery

33

List 3 tests that can detect a fetomaternal hemorrhage

- Weak D
- Rosette test
- Kleihauer-Betke stain

34

Weak D sensitivity

Least sensitive; requires at least 30mL bleed in order to be detected. Result is weak mixed field

35

Fetomaternal hemorrhage kit sensitivity

Sensitive to 2mL bleed of fetal cells into mother; appear as rosettes of D+ cells when viewed microscopically

36

Kleihauer-Betke stain sensitivity

Most sensitive, used to quantify the amount of fetomaternal hemorrhage. Fetal cells appear bright pink, mother's appear as ghost cells

37

List the 4 objectives of an exchange txn for a newborn

- To ↓ level of bilirubin and prevent kernicterus
- Remove baby's sensitized RBCs
- Provide compatible RBCs w/ adequate O2-carrying capacity
- ↓ level of incompatible Ab in baby

38

Principle of Rosette kit test

Rh+ fetal cells coated w/ anti-D form rosettes w/ Rh+ indicator cells. Distinguished from Rh negative RBCs (qualitative)

39

Principle of Kleihauer-Betke test

Maternal blood smear treated w/ acid and stained w/ counterstain. Fetal cells resistant to acid remain pink, maternal cells appear as ghosts. After quantitating # of fetal cells present, yield is in % fetal cells

40

Purpose of ABO/Rh prenatal test

See if mom is group O (predict possibility of ABO/HDFN) and to see if mom is Rh negative, in which she will need antenatal RHIG at 28 weeks

41

Purpose of IAT prenatal test

Screens for unexpected IgG Abs, those capable fo causing HDFN

42

Purpose of titer prenatal test

Monitors Ab production in mom. If ↑, corresponds w/ baby affected by HDFN. Indicates need for additional testing, beginning w/ amniocentesis

43

Purpose of amniocentesis prenatal test

Sample of amniotic fluid is tested fro amount of bilirubin present, plotted on Liley graph

44

Purpose of Percutaneous Umbilical Blood Sampling (aka cordocentesis)

Takes actual sample of baby's blood that can be tested for hgb, hct, ABO/Rh, DAT, Ag typing

45

Purpose of paternal testing

Determine zygosity of father fro offending Ag, thus aiding in predicting occurence of HDFN in baby

46

Rh Immunge Globulin (RHIG)
- Objective/purpose for administration

Prevent the formation of anti-D in an Rh negative individual who has been exposed to Rh positive RBCs (here, fetal cells) by passive immunization w/ anti-D

47

Rh Immunge Globulin (RHIG)
- Criteria for candidacy

- Mother must be Rh negative
- Infant must be Rh positive (including weak D)
- Mother must not be already immunized to the D Ag (no anti-D)
- Infants cannot have anti-D coating their cells (DAT+ due to anti-D)

48

Rh Immunge Globulin (RHIG)
- Indications for use

?

49

Rh Immunge Globulin (RHIG)
- Active ingredient

Sterile IgG anti-D

50

Rh Immunge Globulin (RHIG)
- Standard dose

300ug neutralizes 30mL WB or 15mL packed cell bleed

51

Rh Immunge Globulin (RHIG)
- Time frame

Ideally, w/in 72 hours from delivery; better to give late than not at all

52

Rh Immunge Globulin (RHIG)
- Route of administration

Intramuscularly

53

Calculate fetal bleed and # of vials RHIG needed

(# fetal cells/total # of cells) x 100 = % fetal cells
% fetal cells x 50 = volume of FMH (WB)
(FMH/30) = # vials + 1

54

Effects of antenatal RHIG may have on a patient's IAT results at the time of the delivery

Antenatal dose of RHIG can still be detected in the mother's circulation at time of delivery (1/2 life of anti-D is 22 days). After confirming recipt of RHIG at 28 week mark, this anti-D can be ignored. Mother will still need another dose of RHIG postpartum. Occasionally, the anti-D from RHIG will coat the baby's cells giving a DAT+

55

Rosette
- Positive appearance
- Negative appearance

- Pos: ≥5 rosettes/5 fields (at least 7.5mL fetal bleed into mom)
- Neg: 0-4 rosettes/5 fields (indicates bleed b/w 2.5-7.5mL)
- Neg: 0 rosettes/5 fields (< 2.5 mL fetal bleed into mom)