Question

64. Blood for exchange transfusion was requested for a baby with bilirubin of 18.0 mg. The mother is O negative with anti-D (1:2048). The baby is A positive with a 4+ direct antiglobulin test (DAT) due to anti-D. Discuss product selection and preparation.  

65. A postpartum test for weak D (Du) on a patient in Labor and Delivery showed a weakly Positive mixed field reaction. Antepartum records show the patient to be weak D negative. Discuss the possible reason for the current results, state whether RhIG is indicated, and suggest confirmation tests.

Answer 1

64.

mother is O Negative with anti-D and her newborn baby is A Negative with a positive DAT.

This is most likely ABO HDFN

Blood selection for an exchange transfusion includes:

- Group O cells suspended in group AB plasma
- fresh blood less than 5 days old
- Irradiation
- CMV negative

65.

negative result in the immediate spin phase but agglutination in the D tube following incubation (with no agglutination in the DC tube) indicates a positive test for weak D. Lack of agglutination is a negative test and the patient is considered truly D negative. Agglutination in the DC tube invalidates the test.

A true weak D should give at least a 2+ positive result. Weaker results may be due to mixed field agglutination in an Rh negative individual who received Rh positive blood, or vice-versa. Obtain a recent transfusion history on patients who give inconclusive weak D results