RhIg

Question 1

why do most cases of HDFN due to anti-D occur in Caucasian females?

Answer 1

12-18% Caucasian females are D negative

Question 2

most common cause of fetal-maternal hemorrhage

Answer 2

delivery

Question 3

what percent of Rh negative people seem incapable of producing anti-D regardless of how many exposures to the D antigen?

Answer 3

~30%

Question 4

causes of fetal-maternal hemorrhage

Answer 4

delivery
amniocentesis
spontaneous or induced abortion
chorionic villus sampling
cordocentesis
rupture of ectopic pregnancy
blunt trauma to abdomen

Question 5

what pregnancy is affected by fetal-maternal bleed?

Answer 5

second and subsequent

Question 6

high-titer IgG D antibodies of human origin commercially prepared for injection IM or IV

Answer 6

Rh Immune Globulin

Question 7

incidence of anti-D when RhIg is given at 28 weeks antepartum and postpartum

Answer 7

0.1%

Question 8

who is a candidate for RhIg?

Answer 8

pregnant Rh negative women with no detectable immune anti-D
Rh negative women with no detectable immune anti-D who have delivered an Rh positive or weak D positive newborn
Rh negative female who receives platelets or red cells from Rh positive donor

Question 9

RhIg dose calculation if given Rh positive blood products

Answer 9

vials needed = vol of bleed x Hct / 15

Question 10

RhIg non-candidates

Answer 10

Rh positive
Rh negative women who deliver Rh negative babies
Rh negative women known to have made anti-D (active/immune)

Question 11

anti-D from RhIg may be detected in antibody screen for how long after injection?

Answer 11

up to 6 months

Question 12

expected titer of anti-D due to RhIg

Answer 12

<16

Question 13

does RhIg cross placenta?

Answer 13

yes but no risk to hemolyze

Question 14

can RhIg cause positive DAY at birth?

Answer 14

yes

Question 15

when is RhIg administered?

Answer 15

after any invasive procedure
28 weeks
postpartum within 72 hours after delivery

Question 16

amount of anti-D in one vial of RhIg

Answer 16

300 ug

Question 17

1 vial of RhIg covers what volume of fetal bleed?

Answer 17

30 mL whole blood

15 mL packed cells

Question 18

screening test for fetal-maternal hemorrhage

Answer 18

Rosette test/fetal bleed screen

Question 19

what does Rosette test detect?

Answer 19

Rh positive cells

Question 20

mechanism of fetal bleed screen

Answer 20

D+ indicator cells form rosettes around D+ fetal cells

Question 21

is fetal bleed screen qualitative or quantitative?

Answer 21

qualitative

Question 22

steps of rosette test

Answer 22

incubating mother’s red cell suspension with reagent anti-D
washing
D positive indicator cells added
examined microscopically for rosettes of indicator cells surrounding antibody-coated Rh positive cells

Question 23

confirmation test for fetal-maternal hemorrhage

Answer 23

Kleihauer-Betke

Question 24

when is KB test performed?

Answer 24

fetal bleed screen is positive

Question 25

what does KB test detect?

Answer 25

fetal cells

Question 26

is KB test qualitative or quantitative?

Answer 26

quantitative

Question 27

what do fetal cells look like in KB test?

Answer 27

bright pink

Question 28

what do maternal cells look like in KB test?

Answer 28

"ghost" cells

Question 29

how many cells are counted in KB test?

Answer 29

2000

Question 30

what test is used to determine fetal-maternal hemorrhage is mother is weak D positive?

Answer 30

KB

Question 31

RhIg dose calculation (fetal bleed)

Answer 31

% fetal cells x 50 / 30

Question 32

mL fetal hemorrhage calculation

Answer 32

KB percent x 50

Question 33

what safety margin is recommended for fetal maternal hemorrhage when giving RhIg?

Answer 33

add 1 to calculated number of vials

Question 34

when is mini or micro dose of RhIg given?

Answer 34

before 13 weeks gestation after miscarriages or abortions

Question 35

how is flow cytometry used in fetal-maternal hemorrhage?

Answer 35

uses reagent containing monoclonal antibody to hemoglobin F

Question 36

requirement of AABB standards in regards to fetal-maternal hemorrhage

Answer 36

a test to detect FMN is excess of 30 mL be employed to determine if multiple doses of RhIg should be admininstered