Hemolytic disease of the newborn

Question 1

What is erythroblastosis fetalis? What is it caused by?

Answer 1

Hemolytic disease of the newborn is caused by blood group incompatibility between the developing fetus and the mother. Most cases (97%) are due to anti‐Rh‐antibodies.

Question 2

How does sensitization to Rh antigens occur?

Answer 2

occurs in about 10‐15 % of Rh‐negative women who bear children of Rh-positive men; occurs via fetal maternal bleeding at the time of delivery; fetal cells crossing the placental barrier and enter the maternal circulation

Question 3

What factors can induce sensitization?

Answer 3

Situations which allow for exchange of fetal and maternal blood such as:
preeclampsia
abruption placentae
spontaneous or therapeutic abortion
cesarean section
amniocentesis
trauma

Question 4

Why is the first pregnancy of a Rh negative women with a Rh positive baby uneventful?

Answer 4

The initial antibodies are IgM, which is a pentamer, too large to cross the placental barrier.

Question 5

What can happen in the second pregnancy of a Rh negative women with a Rh positive baby?

Answer 5

There is an anamnestic response in which antibodies are IgG; they cross the placental barrier and attack fetal RBCs, which are coated with Ab and then destroyed in the spleen

Question 6

The fetal compensation that occurs to the resulting anemia happens in the (1) producing (2)

Answer 6

1. fetal bone marrow, liver and
   spleen
2. hepatosplenomegaly

Question 7

Describe the sequence of events leading to hydrops fetalis.

Answer 7

Anemia and high output cardiac failure due to cardiac dilatation —> liver dysfunction —> decreased albumin production —> edema —> hydrops fetalis

Question 8

If there is fetal compensation what signs and symptoms occur?

Answer 8

hepatosplenomegaly
jaundice soon after birth due to accumulation of unconjugated bilirubin
pallor
generalized edema

Question 9

Why aren’t neonates with compensated erythroblastosis fetalis born with jaundice?

Answer 9

Prior to birth the unconjugated bilirubin is excreted via the
placenta

Question 10

Jaundice occurs in part because (1) are not developed and thus are unable to conjugate the excess the bilirubin produced

Answer 10

1. fetal glucuronyl transferase enzymes

refers to eryhtroblastosis fetalis

Question 11

Unconjugated fraction of bilirubin is (1) soluble and accumulates in the (2) leading to (3)

Answer 11

1. fat
2. cerebellum and basal ganglia
3. encephalopathy with fetal lethargy, spasticity and hypotonia

Question 12

How can fetal anemia be circumvented?

Answer 12

Monitor titer levels of Rh antibodies in mother
Early delivery (2-4 weeks preterm) of the fetus along with transfusions (trans abdominal into fetal peritoneal cavity) or exchange transfusions (at birth) with Rh‐negative red cells to remove excess fetal bilirubin and treat fetal anemia
OR
Prevent sensitization in the mother

Question 13

How can sensitization be prevented in the mother?

Answer 13

IM injection of Rh immunoglobulin composed of Ƴ‐globulin containing Rh‐antibody (called Rho‐gam), coats the Rh‐Positive red cells of the fetus and thus prevents sensitization in the mother. This is given within 72 hours of a Rh‐negative mother delivering a Rh positive infant.

It can also be given after spontaneous or therapeutic abortion, cesarean section, amniocentesis, or other situations when there is risk of bleeding across placenta.

Question 14

given routinely at 28 weeks gestation to all unsensitized Rh‐negative mothers

Answer 14

Rho‐gam

Question 15

(1) incompatibility between mother and fetus also can cause hemolytic disease of the newborn but
most cases are not severe or life threatening

Answer 15

1. ABO

Question 16

Other Abs associated with hemolytic disease of newborn

Answer 16

Kell
Duffy
Kidd

Question 17

Coombs’ test in hemolytic disease of the newborn

Answer 17

positive

Question 18

reticulocyte count in hemolytic disease of the newborn

Answer 18

increased

Question 19

Bilirubin in hemolytic disease of the newborn

Answer 19

increased

Question 20

Other lab findings in hemolytic disease of the newborn

Answer 20

Peripheral nucleated Rbc’s

Polychromatophylia

Question 21

extra staining due to too many immature red blood cells (RBCs)

Answer 21

Polychromatophylia

Question 22

Platelet count in hemolytic disease of the newborn

Answer 22

decreased

Question 23

Ab titers of (1) frequently develop hydrops

Answer 23

1. 1:16 -1:32

Question 24

Antibodies that are involved in hemolytic disease of the newborn: ID
which one treated with Rho-GAM

Answer 24

Rh(D)–> 97% of cases; Kell; Duffy and Kidd.

only Rh(D) is prevented by Rhogam

Question 25

polychromatophylia indicates

Answer 25

↑turnover of RBCs

Question 26

Transfusion Support occurs when? 1)

trans abdominal into 2); Ultrasound directed into umbilical vein –> infuse compatible 3) red cells

Answer 26

1) in utero
2) fetal peritoneal cavity
3) Rh negative

Question 27

Exchange Transfusion is done when? 1)
Usually these babies are born 2)
Unconjugated Bilirubin above 3) is very serious;

Answer 27

1) post-delivery
2) EARLY; (2-4 weeks pre-term)
3) 20 mg/dl

Question 28

Exchange Transfusion:
1) cells are exchanged for the fetus’s blood volume;
Exchange to 2x infants blood volume –> removes 85% of 2) and 50% of 3)

Answer 28

1) Group O Rh negative
2) RBCs
3) bilirubin

Question 29

1) reduces sensitization to less than 1.3%.

Answer 29

1) Rhogam

Question 30

Consider Rhogam use in 1) (3 conditions)

Answer 30

1) post amniocentesis, post abortion, and post obstetrical procedures

Question 31

(300 micro grams of Rho-GAM to all 1) women at 28 wks is effective in reducing the incidence and frequency of hemolytic disease in the newborn).

Answer 31

1) Rh neg unsensitized

Question 32

Rho-GAM:
IM injection of Rh immunoglobulin composed of 1) (called Rho‐gam), coats the 2) of the fetus and thus prevents sensitization in the mother. This is given within 72 hours of a Rh‐negative mother delivering a Rh positive infant.

Answer 32

1) Ƴ‐globulin containing Rh‐antibody

2) Rh‐Positive red cells