Massive fetomaternal hemorrhage: clearance of fetal red blood cells after intravenous anti-D prophylaxis monitored by flow cytometry.
BACKGROUND
The clearance of D+ red blood cells (RBCs) from the circulation in D- individuals mediated by passively administered anti-D occurs by opsonization with the antibody and subsequent removal in the spleen. Few data exist on the kinetics of clearance of large volumes of D+ RBCs from the maternal circulation by anti-D in clinical cases of massive fetomaternal hemorrhage (FMH).


METHODS
A 33-year-old D- woman delivered a D+ female infant by emergency cesarean section for suspected fetal anemia. A massive FMH, initially estimated to be approximately 142 mL of RBCs, was found. In addition to the standard dose of intramuscular (IM) anti-D (300 microg) given immediately after delivery, 2700 microg of anti-D was administered intravenously (IV). The clearance of D+ fetal cells from the maternal circulation was monitored by flow cytometry in samples obtained on a daily basis using anti-D. The mother had no detectable anti-D 6 months after delivery.


RESULTS
No clearance of fetal cells was apparent after the insufficient dose of IM anti-D. The IV administration of anti-D caused accelerated clearance of D+ fetal RBCs with a t1/2 of 24.5 hours. D+ reticulocytes comprised 4.2 percent of all D+ cells in the maternal circulation at delivery suggesting acute fetal blood loss.


CONCLUSIONS
The approach used in this report allowed a detailed analysis of the kinetics related to the clearance of fetal D+ RBCs. Simultaneous measurements of fetal reticulocytes and fetal RBCs in maternal blood may establish the timing of an FMH.
Larsen
Rune
R
Department of Clinical Immunology, University Hospital of Copenhagen (Rigshospitalet), Copenhagen, Denmark.
Berkowicz
Adela
A
Lousen
Thea
T
Hedegaard
Morten
M
Clausen
Frederik B
FB
Krog
Grethe R
GR
Dziegiel
Morten H
MH
D000328:Adult; D002585:Cesarean Section; D004899:Erythroblastosis, Fetal / Q000097:blood / Q000276:immunology; D005260:Female; D005312:Fetal Blood / Q000166:cytology*; D005331:Fetomaternal Transfusion / Q000097:blood* / Q000276:immunology*; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D007231:Infant, Newborn; D007275:Injections, Intravenous; D007518:Isoantibodies / Q000008:administration & dosage* / Q000097:blood / Q000276:immunology; D011247:Pregnancy; D011256:Pregnancy Outcome; D012156:Reticulocytes / Q000166:cytology; D018029:Rho(D) Immune Globulin; D013154:Spleen / Q000166:cytology
D007518:Isoantibodies; C061961:RHO(D) antibody; D018029:Rho(D) Immune Globulin