Hemolytic Disease of the Newborn

Which blood type may be transfused to an AB-positive baby who has HDN caused by anti-D? A. AB negative, CMV negative, Hgb S negative; irradiated or O negative; CMV negative, Hgb S negative B. AB positive, CMV negative; irradiated or O positive, CMV negative C. AB negative only D. O negative only

A Either AB-negative or O-negative RBCs may be given to an AB-positive baby because both types are ABO compatible and lack the D antigen. Harr, Robert R. Medical Laboratory Science Review (Page 160). F.A. Davis Company. Kindle Edition.

What should be done when a woman who is 24 weeks pregnant has a positive antibody screen? A. Perform an antibody identification panel; titer if necessary B. No need to do anything until 30 weeks gestation C. Administer Rh immune globulin (RhIg) D. Adsorb the antibody onto antigen-positive cells

A The identification of the antibody is very important at this stage of the pregnancy. If the antibody is determined to be clinically significant, then a titer may determine the strength of the antibody and the need for clinical intervention. Harr, Robert R. Medical Laboratory Science Review (Page 158). F.A. Davis Company. Kindle Edition.

What testing is done for exchange transfusion when the mother's serum contains an alloantibody? A. Crossmatch and antibody screen B. ABO, Rh, antibody screen, and crossmatch C. ABO, Rh, antibody screen D. ABO and Rh only

B ABO (forward) and Rh are required. An antibody screen using either the neonatal serum or maternal serum is required. A crossmatch is necessary as long as maternal antibody persists in the infant's blood. Harr, Robert R. Medical Laboratory Science Review (Page 160). F.A. Davis Company. Kindle Edition.

Which of the following patients would be a candidate for RhIg? A. B-positive mother; B-negative baby; first pregnancy; no anti-D in mother B. O-negative mother; A-positive baby; second pregnancy; no anti-D in mother C. A-negative mother; O-negative baby; fourth pregnancy; anti-D in mother D. AB-negative mother; B-positive baby; second pregnancy; anti-D in mother

B An O-negative mother who gives birth to an A-positive baby and has no anti-D formed from a previous pregnancy would be a candidate for RhIg. A mother who already has active anti-D or a mother who gives birth to an Rh-negative baby is not a candidate for RhIg. Anti-D formation via active immunization typically has a titer >4, compared with passive administration of anti-D, which has a titer <4. Harr, Robert R. Medical Laboratory Science Review (Page 159). F.A. Davis Company. Kindle Edition.

All of the following are routinely performed on a cord blood sample except: A. Forward ABO typing B. Antibody screen C. Rh typing D. DAT

B An antibody screen is not performed routinely on a cord blood sample because a baby does not make antibodies until about 6 months of age. Any antibodies detected in a cord blood sample come from the mother. Harr, Robert R. Medical Laboratory Science Review (Page 160). F.A. Davis Company. Kindle Edition.

What can be done if HDN is caused by maternal anti-K? A. Give Kell immune globulin B. Monitor the mother's antibody level C. Prevent formation of K-positive cells in the fetus D. Not a problem; anti-K is not known to cause HDN

B Anti-D is the only antibody for which prevention of HDN is possible. If a pregnant woman develops anti-K, she will be monitored to determine if the antibody level and signs of fetal distress necessitate clinical intervention. Harr, Robert R. Medical Laboratory Science Review (Page 159). F.A. Davis Company. Kindle Edition.

Kernicterus is caused by the effects of: A. Anemia B. Unconjugated bilirubin C. Antibody specificity D. Antibody titer

B Kernicterus occurs because of high levels of unconjugated bilirubin. High levels of this pigment cross into the central nervous system, causing brain damage to the infant. Harr, Robert R. Medical Laboratory Science Review (Page 160). F.A. Davis Company. Kindle Edition.

All of the following are interventions for fetal distress caused by maternal antibodies attacking fetal cells except: A. Intrauterine transfusion B. Plasmapheresis on the mother C. Transfusion of antigen-positive cells to the mother D. Early induction of labor

C Transfusion of antigen-positive cells to the mother who already has an antibody might cause a transfusion reaction and/or evoke an even stronger antibody response, possibly causing more harm to the fetus. Harr, Robert R. Medical Laboratory Science Review (Page 158). F.A. Davis Company. Kindle Edition.

All of the following are reasons for a positive DAT on cord blood cells of a newborn except: A. High concentrations of Wharton's jelly on cord cells B. Immune anti-A from an O mother on the cells of an A baby C. Immune anti-D from an Rh negative mother on the cells of an Rh-positive baby D. Immune anti-K from an K-negative mother on the cells of a K-negative baby

D Immune anti-K from the mother would not coat the baby's red cells if they did not contain the K antigen; therefore, the DAT would be negative. Harr, Robert R. Medical Laboratory Science Review (Page 158). F.A. Davis Company. Kindle Edition.

A Kleihauer-Betke acid elution test identifies 40 fetal cells in 2,000 maternal red cells. How many full doses of RhIg are indicated? A. 1 B. 2 C. 3 D. 4

D To calculate the number of vials of RhIg to infuse, divide 40 by 2,000 and multiply by 5,000, which is the estimated total blood volume of the mother in milliliters. Divide this number by 30 to arrive at the number of doses. When the number to the right of the decimal point is less than 5, round down and add one dose of RhIg. Conversely, when the number to the right of the decimal point is 5 or greater, round up and add one dose of RhIg. In this example, the number of doses is 3.3. Rounding down and adding 1 vial gives an answer of 4 vials. Harr, Robert R. Medical Laboratory Science Review (Page 160). F.A. Davis Company. Kindle Edition.