Detection of fetomaternal hemorrhage.
The prevention of Rhesus D alloimmunization through Rh immune globulin (RhIg) administration is the major indication for the accurate detection and quantification of fetomaternal hemorrhage (FMH). In the setting of D incompatibility, D-positive fetal cells can sensitize the D-negative mother, resulting in maternal anti-D alloantibody production. These anti-D alloantibodies may lead to undesirable sequelae such as hemolytic disease of the newborn (HDN). Since the widespread adoption of FMH screening and RhIg immunoprophylaxis, the overall risk of Rh alloimmunization and infant mortality from HDN has substantially decreased. The rosette screen, the initial test of choice, is highly sensitive in qualitatively detecting 10 mL of fetal whole blood in the maternal circulation. As the screen is reliant on the presence of the D antigen to distinguish fetal from maternal cells, it cannot be used to detect FMH in D-positive mothers or in D-negative mothers carrying a D-negative fetus. The Kleihauer-Betke acid-elution test, the most widely used confirmatory test for quantifying FMH, relies on the principle that fetal RBCs contain mostly fetal hemoglobin (HbF), which is resistant to acid-elution whereas adult hemoglobin is acid-sensitive. Although the Kleihauer-Betke test is inexpensive and requires no special equipment, it lacks standardization and precision, and may not be accurate in conditions with elevated F-cells. Anti-HbF flow cytometry is a promising alternative, although its use is limited by equipment and staffing costs. Hematology analyzers with flow cytometry capabilities may be adapted for fetal cell detection, thus giving clinical laboratories a potentially attractive automated alternative for quantifying FMH.
Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. ykim13@partners.org
Yeowon A
YA
Kim
Robert S
RS
Makar
D000143:Acids / Q000494:pharmacology; D005260:Female; D005312:Fetal Blood / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D005319:Fetal Hemoglobin / Q000187:drug effects / Q000276:immunology; D005331:Fetomaternal Transfusion / Q000097:blood / Q000175:diagnosis*; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D007518:Isoantibodies / Q000276:immunology / Q000627:therapeutic use; D011247:Pregnancy; D012203:Rh Isoimmunization / Q000209:etiology / Q000517:prevention & control; D012204:Rh-Hr Blood-Group System / Q000235:genetics; D018029:Rho(D) Immune Globulin; D012397:Rosette Formation; D012680:Sensitivity and Specificity; D012995:Solubility; D013194:Staining and Labeling
D000143:Acids; D007518:Isoantibodies; C061961:RHO(D) antibody; D012204:Rh-Hr Blood-Group System; D018029:Rho(D) Immune Globulin; D005319:Fetal Hemoglobin