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MLS Blood Bank > Quiz 3 > Flashcards

Quiz 3 Flashcards

1
Q

Why do we do prenatal type and screens?

A
  • To ID clinically significant Abs in mom (that can cross the placenta)
  • To determine mom’s need for RhIG (Rh neg moms)
  • To ID a potential ABO HDFN situation
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2
Q

What kind of Abs do we titer in a pregnant woman?

A

Abs that react at 37C (IgG)

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3
Q

What are the basic steps of an Ab titer?

A
  • Make a serial dilution with the pt plasma
  • React plasma with reagent cells containing Ag for corresponding Ab
  • Read agglutination reaction from highest dilution to lowest
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4
Q

How often do we titer pregnant women with significant Abs?

A

Every month until the end of the 2nd trimester and every couple of weeks throughout the 3rd trimester.

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5
Q

What kind of reagent cells do we use for a titer on a pregnant woman?

A

Homozygous or heterozygous as long as it’s consistent throughout the pregnancy

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6
Q

What is the end-point of an Ab titer?

A

The highest dilution showing a 1+ reaction

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7
Q

What are critical titer results?

A
  • Anti-D >/= 16
  • Anti-K >/= 8
  • Any other IgG Ab >/= 16
  • A two tube rise in titer (ex. 1:2 - 1:8)
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8
Q

Why does anti-K have a lower critical titer than anti-D?

A
  • K develops sooner in gestational age than D
  • K is expressed on nRBCs and mature RBCs, where D is only expressed on mature RBCs
  • Anti-K is more efficient at crossing the placenta
  • Anemia caused by anti-K can be more severe earlier in gestation with a lower titer
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9
Q

How should you run titers to avoid subjectivity?

A

In parallel (last month’s sample and present sample), reading from highest titer to lowest titer

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10
Q

What might a physician do once the critical threshold is reached for an Ab titer?

A

They might begin monitoring the fetal anemia with Doppler US.

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11
Q

What tests are required before an exchange transfusion or intrauterine transfusion?

A
  • Type and screen, Ab ID, and crossmatch

- Do type and screen on baby if you can for an exchange transfusion

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12
Q

What type of blood is used for an exchange or intrauterine transfusion? What are the special requirements?

A
  • O neg
  • Freshest available (collected within 7 days)
  • CMV neg
  • Hbg S neg
  • Leuk reduced (for febrile reactions)
  • Irradiated (for GVHD)
  • Washed (to remove extra volume)
  • Ag negative for mom’s Abs
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13
Q

What additional prep needs to be done before an exchange transfusion? Why?

A
  • AB plasma is added to O neg blood

- To replace the entire whole blood volume

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14
Q

What tests are done routinely on cord blood?

A

Forward type and DAT

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15
Q

What is the purpose of doing cord blood testing?

A
  • To determine of mom needs postpartum RhIG (Rh neg mom and Rh pos baby)
  • To determine if baby’s cells are coated with an allo-Ab
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16
Q

What reagent is used for cold blood DAT?

A

Monoclonal IgG

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17
Q

When is ABO HDFN most likely to occur? Why?

A

When the mom is type O, because mom will have a higher titer of anti-A and anti-B Abs.

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18
Q

What will the baby’s DAT result be after ABO HDFN occurs?

A

It could be DAT pos or neg

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19
Q

What is done next if a baby has a positive DAT after ABO HDFN?

A

1st - ABO IAT testing using cord serum and screening cells

2nd - an elution can be done to see what Ab is coating the baby’s cells

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20
Q

What basic tests need to be done before a neonatal transfusion (non HDFN)?

A

Forward type and Ab screen on baby’s sample

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21
Q

If mom has an Ab, what extra steps need to be done before a neonatal transfusion (non HDFN)?

A

The type and screen still need to be done on the baby and an Ab ID and crossmatch can be done with mom’s sample.

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22
Q

If mom has a history of clinically significant Ab that is not showing up, how should blood be chosen for a neonatal transfusion?

A

The blood should be negative for the antigen corresponding to mom’s Abs.

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23
Q

When should RhIG be given?

A
  • At 28 weeks for Rh neg moms
  • In the case of a traumatic event or an invasive procedure
  • If the baby is born in breech position
  • In the case of vaginal bleeding
  • Postpartum if the baby is Rh pos
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24
Q

If a mom screens positive for anti-D, they can not be given RhIG. T or F?

A

True

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25
Q

Does DTT treatment weaken/destroy real anti-D or RhIG?

A

The real anti-D

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26
Q

If mom and baby are Rh neg, what test should be done next?

A

Weak-D testing on baby

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27
Q

How long can RhIG circulate?

A

Up to 3 months

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28
Q

How can anti-D be differentiated from RhIG?

A

A titer can be performed

  • RhIG rarely titers above 4
  • The specimen can be treated by DTT
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29
Q

What is the principle of the fetal maternal bleed screen (aka Rosette test or FMH screen)? Is it quantitative or qualitative?

A

Anti-D antisera is used to detect strong D antigen positive cells
(with the use of IgG or indicator cells)

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30
Q

What might be the cause of a false positive in a FMH screen test?

A

Mom could be weak D pos or DAT pos (indicator cells will bind)

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31
Q

What are possible causes of false negatives in FMH screen testing?

A
  • There is less than 10 mL of fetal blood present in the sample
  • Baby is weak D pos (doesn’t have strong expression of antigen)
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32
Q

What should be done when a FMH screen is negative?

A

The mom should be given a single dose of RhIG

33
Q

What should be done if the FMH screen is positive?

A

A KB test or flow cytometry to confirm and quantitate the FMH - for RhIG dosage

34
Q

What is the principle behind KB testing?

A

Fetal Hgb is resistant to acid treatment (and adult Hgb gets washed out, leaving mom cells a pale color)

35
Q

What are the controls for KB testing?

A

Neg - adult male RBCs

Pos - mix of cord cells and male RBCs

36
Q

What are possible causes of false positives in KB testing?

A
  • Overstaining
  • Small B lymphs that look like fetal cells
  • Partial staining of adult cells
  • Mom makes Hgb F
37
Q

How are cell counts for the KB test done?

A
  • Two slides are counted and averaged
  • You can count 2,000 cells starting at the feathered edge and use the following calculation - # of fetal cells/total (x 5,000 mL)
  • Or you can use a Miller disc and use the following calculation - % fetal cells x 50mL
38
Q

What cells do you count in each square on the Miller disc for a KB test?

A

You count adult cells in the small square and fetal cells in both (the whole field)

39
Q

How many mLs of hemorrhage does 1 dose of RhIG cover?

A

30 mLs

40
Q

What is a critical result for a fetal screen?

A

Pos or neg test is critical, because even if the test is negative the mom should receive one dose of postpartum RhIG within 72 hours of giving birth

41
Q

What is the transfusion trigger for RBCs?

A

Hgb less than 7 g/mL

42
Q

What is the transfusion trigger for platelets (w/ no additional implications)?

A

Less than 10,000 plts

43
Q

What is the plt transfusion trigger with a risk of bleeding?

A

Less than 20,000

44
Q

What is the plt transfusion trigger if the patient is bleeding or going into invasive surgery?

A

Less than 50,000

45
Q

What is the plt transfusion trigger for a patient who will be undergoing neurosurgery or has a head bleed (SAH, SDH, ICH, etc.)?

A

100,000

46
Q

What is the transfusion trigger for plts if the patient is on an anticoag drug?

A

Anyone taking anticoags who is bleeding, has a surgery planned, or has a potential of internal bleeding can qualifies for a plt transfusion.

47
Q

What is the FFP transfusion trigger?

A

An INR of 1.5 or greater or a prolonged PT/aPTT (usually approx. 1.5 x the upper limit)

48
Q

Which contains more factor VIII, Cryo or FFP?

A

Cryo

49
Q

What is the transfusion trigger for Cryo?

A

Less than 100 mg/dL of fibrinogen

50
Q

What product is best to use as an alternative hemophilia and/or VWD treatment?

A

Cryo

51
Q

If the patient doesn’t qualify for the products that have been requested, what should be done next?

A

You can ask for more information and/or consult with the BB supervisor
- A prospective review may be done to evaluate patient needs

52
Q

What are the expected increases in Hbg and Hct after one RBC unit has been transfused?

A

Hgb - increase in 1 g/dL

Hct - increase by 3%

53
Q

How many concentrates of plts are pooled to make 1 apheresis-size unit?

A

6 concentrates are pooled to make 1 apheresis unit

54
Q

What is the expected increase after one apheresis sized unit?

A

Plts should increased by 30,000 - 60,000.

55
Q

What is the expected increase after one unit of plt concentrate has been given?

A

Plts should increase by 5,000 to 10,000

56
Q

When is plt refractoriness indicated?

A

It is indicated when you don’t see the expected increase after transfusion of plts

57
Q

What are the types of plt refractoriness?

A
  1. Mechanical
    a. spleen sequestration
  2. Serological
    a. anti-platelet of anti-HLA in recipient
    b. TTP or ITP
  3. Consumption
    a. DIC
    b. sepsis
58
Q

What are some actions to take that may help eliminate platelet refractoriness?

A

You could give…

  • HPA-1 negative platelets in the cause of a anti-plt Ab
  • HLA typed plts
  • Or crossmatched platelets
59
Q

When should a transfusion “bump” be checked?

A

Approx. 1 hour after transfusion

60
Q

Once a unit of platelet concentrate is opened for pooling, how long until it expires?

A

4 hours after it is spiked (kept at room temp)

61
Q

How many single units of cryo are pooled to make one adult dose?

A

10 single units

62
Q

Once a unit of cryo is spiked, how long before it expires?

A

4 hours

63
Q

If cryo is pooled before freezing, how long is the expiration after thawing?

A

6 hours from thawing time

64
Q

How long do cryo and plasma last for when they’re frozen?

A

Once year

65
Q

Once you thaw plasma how long is it good for?

A
  • 24 hours from thawing (as thawed FFP)
  • Or 5 days if relabeled as thawed plasma
  • Refrigerated after thawing
66
Q

Why does FFP expire 24 hours after thawing?

A

Because of the labile coag factors

67
Q

How long are RBCs good for after the unit has been spiked?

A

24 hours

68
Q

When preparing small volumes of RBCs from larger units there are two methods that can be used. What are they, and what are the expirations for the units derived?

A
  • Syringe method - Exp: in 24 hours

- Bag method with tube welder - Exp: At the original expiration date

69
Q

What effect does washing red cells have on the hct?

A

It increased the hct

70
Q

When reconstituting RBCs, what is added? How does this affect the expiration?

A

Plasma is added (to make whole blood), the expiration changes to 24 hours anytime the system is opened

71
Q

What is the basic method for irradiation? How does it affect the expiration?

A

25 grays of gamma radiation to the midline of the product; the expiration changes to 28 days from the date of irradiation or the original exp. date, whichever comes first

72
Q

What are the minimum requirements to check for when issuing blood?

A

2 pt IDs, compatibility testing results, and visual inspection of the product

73
Q

How fast can FFP, plts, and cryo be transfused?

A

As fast as the patient can tolerate

74
Q

How fast are RBCs transfused?

A

250 mL/hr

75
Q

What is the shape of the standard filter apparatus? What are the rest of the components?

A

Y-shape

  • inline filter for 150-260 microns (microclots)
  • pump
  • blood warmers can be attached if needed
76
Q

How long can our DH coolers store blood? What is the temp range?

A

4 hours at 1-6C

77
Q

What is the transport temp rage for RBCs and FFP when not in a cooler?

A

1-10C

takes about 15 min to get over 10C

78
Q

How should plts be returned to the lab?

A

Swirling and 20-24C (same for cryo, but no swirl)

79
Q

How should plasma be returned (it goes out thawed)?

A

It should be cooling towards 1-10C (cooler than when it went out, because its kept in a separate cooler)

MLS Blood Bank (3 decks)

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