Hemolytic Disease of Fetus and Newborn

Question 1

How does HDFN happen?

Answer 1

Infants inherit antigen from biological father. Mother has corresponding IgG antibody against the antigen (either sensitized by previous pregnancies or transfusions).

Maternal antibody crosses placenta and binds to fetal cells, causing anemia and hyperbilirubinemia.

Question 2

What can high levels of bilirubin do to an infant in HDFN?

Answer 2

Bilirubin is a neurotoxin causing brain damage called KERNICTERUS

Question 3

What is KERNICTERUS and what is it caused by?

Answer 3

A type of jaundice causing brain damage in infants due to hemolytic disease of the fetus and newborn

Question 4

What is the treatment of choice for HDFN?

Answer 4

Phototherapy or exchange transfusion

Question 5

What is an intrauterine transfusion?

Answer 5

Intrauterine transfusion is a procedure in which red blood cells from a donor are injected into the fetus.

May be recommended if fetus has anemia.

Question 6

What is the AABB recommended titer method for intrauterine transfusion?

Answer 6

saline AHG incubated for 60 mins at 37C

Question 7

What is the critical titer for most antibodies for intrauterine transfusion?

Answer 7

16 at AHG

Question 8

What is the critical titer for Anti-K for intrauterine transfusion?

Answer 8

8 at AHG

Question 9

What device/method can help establish severity of HDFN?

Answer 9

Ultrasound

Color Doppler ultrasonography

Question 10

What are the units selected for intrauterine transfusion?

Answer 10

Group O, Rh negative

Should be irradiated, from CMV-negative donor or leukoreduced

Should be negative for Hgb S

Should be less than 7 days old

Question 11

What is an exchange transfusion?

Answer 11

Slowly removing the person’s blood and replacing it with fresh donor blood or plasma.

Question 12

What is exchange transfusion used for in HDFN?

Answer 12

Exchange transfusion is used to reduce bilirubin levels and remove maternal antibodies in HDFN.

Question 13

What blood group is used for exchange transfusion in HDFN?

Answer 13

Group O if the HDFN is of ABO type.

If it is an Rh HDFN, use D negative

Question 14

Age of unit and preservative used for exchange transfusion

Answer 14

Less than 5-7 days old

CPDA-1

Question 15

HDFN due to ABO or Rh antibodies will cause increased bilirubin? (>20mg/dl)

Answer 15

Rh

Question 16

What DAT result would you see with ABO versus Rh antibodies in HDFN?

Answer 16

ABO –> weak/negative DAT

Rh –> positive DAT

Question 17

Which type of HDFN would an exchange transfusion be more likely needed?

Answer 17

HDFN involving Rh antibodies.

Why? In Rh HDFN, bilirubin is high and toxic to the brain and levels >20mg/dl can lead to mental retardation and/or death in infants.

Question 18

Which typically occurs in the FIRST pregnancy? ABO or Rh HDFN?

Answer 18

ABO, usually O mother with A baby.

Question 19

Which does NOT usually occur in the first pregnancy - ABO or Rh HDFN?

Answer 19

Rh HDFN.

Usually due to a D neg mother with a D positive baby; sensitization happens after first pregnancy.

Question 20

What is the single most important diagnostic test in diagnosis of HDFN after birth?

Answer 20

DAT

Question 21

What value of bilirubin will a physician perform an exchange transfusion in HDFN?

Answer 21

When bilirubin approaches 20 mg/dl

Question 22

What is Rh immune globulin?

Answer 22

Other known as Rhogam

Rhogam shot contains concentrated Anti-D that suppresses immune Anti-D formation in women who are Rh- with an Rh+ baby. Basically Rhogam “tricks” your body into thinking it doesn’t need to make antibodies of its own because there’s this outside source that is taking care of it

Question 23

When is Rhogam usually given to Rh negative women?

Answer 23

at 28 weeks, and post-partum within 72 hours of delivery

Question 24

When would Rhogam also be indicated?

Answer 24

For all D negative women after any abdominal trauma or abortion

Question 25

How much Rhogam is in a single dose/vial?

Answer 25

300 ug or 1500 IU

Question 26

How much whole blood can one vial of Rhogam neutralize?

Answer 26

One vial (300 ug or 1500 IU) of rhogam can neutralize 30 mL of whole blood

Question 27

How many RBCs can a single vial or Rhogam neutralize?

Answer 27

One vial (300 ug or 1500 IU) of rhogam can neutralize 15 mL of red cells

Question 28

What is the rosette test?

Answer 28

Rosette test screens for fetal-maternal hemorrhage (FMH) by detecting fetal D+ red cells in maternal Rh negative blood. It is a QUALITATIVE TEST.

If Rosette test is negative, ONE vial of RhIG/Rhogam should be given
If Rosette test is positive, perform a Kleihauer-Betke acid elution or flow cytometry

Question 29

What is the Kleihauer-Betke test?

Answer 29

If the rosette test is positive (detects fetal D+ red cells in maternal Rh negative blood), then perform this test.

The purpose of this test is to QUANTITATE how much of a fetal-maternal bleed has occurred, and subsequently additional doses of Rh Immune Globulin (RhIG) will be given.

Fetal cells resist acid elution and appear PINK
Adult cells are susceptible and appear as GHOST cells

Question 30

Is the rosette test qualitative or quantitative?

Answer 30

Qualitative

Question 31

How do you calculate how many vials of rhogam to give using the Kleihauer-Betke test?

Answer 31

Count 2000 cells total, noting of how many fetal and maternal cells there are.

Divide # of fetal cells by 2000 and multiple by 5000 to determine volume of fetal whole blood bleed.

Ex. Counted 8 fetal cells in 2000 cells.

8/2000 x 5000 = 20mL of fetal whole bleed

Divide 20mL by 30 since 1 vial of RhIG will neutralize 30 ml of fetal bleed

20 ml / 30ml = 0.66 vial (round up to 1) + 1 vial as a safety vial = 2 vials total

If decimal less than .5 round down and still add a safety vial.