The Kleihauer–Betke test is a semiquantitative test to determine the volume of FMH in an Rh1-negative mother and the amount of RhIG necessary to prevent antibody production. The test is done after full-term delivery if newborn anemia is present or when the mother is Rh negative or weak-negative D. The test is also performed on mothers after invasive procedures (e.g., amniocentesis), miscarriages, or trauma.
Obtain a 7-mL maternal venous blood EDTA sample immediately after delivery, invasive procedure (e.g., amniocentesis), miscarriage, or trauma. Observe standard precautions.
Label the specimen with the patient’s name, date, and test(s) ordered and place in a biohazard bag for transport to the laboratory.
Examine the specimen immediately or refrigerate until it can be examined.
Results indicate moderate to great FMH (50%–90% of fetal red blood cells contain fetal hemoglobin).
With full-term delivery, newborn red blood cells must be RhD-positive for the RhD-negative mother to be a candidate for RhIG.
Pretest Patient Care
Explain test purpose and procedure.
Follow guidelines in Chapter 1 for safe, effective, informed pretest care.
Posttest Patient Care
Review test results; report and record findings. Modify the nursing care plan as needed. Counsel the patient regarding the findings; explain the need for possible follow-up testing and treatment, including administration of RhIG to suppress the immunization of fetal red cells or whole blood hemorrhage (Table 8.17).
Some healthcare providers recommend doubling the calculated dose of RhIG because the method of calculating fetal blood is not precise; the results of undertreatment are serious, but the effects of overtreatment are minor.
Follow guidelines in Chapter 1 for safe, effective, informed posttest care.