Is current serologic RhD typing of blood donors sufficient for avoiding immunization of recipients?

BACKGROUND: Avoiding immunization with clinically important antibodies is a primary objective in transfusion medicine. Therefore, it is central to identify the extent of D antigens that escape routine RhD typing of blood donors and to improve methodology if necessary. STUDY DESIGN AND METHODS: We screened 5058 D- donors for the presence of the RHD gene, targeting Exons 5, 7, and 10 with real-time polymerase chain reaction. Samples that were positive in the screen test were investigated further by adsorption-elution, antibody consumption, flow cytometry, and sequencing of all RHD exons with intron-specific primers. Lookback was performed on all recipients of RBCs from RHD+ donors. RESULTS: We found 13 RHD+ samples (0.26%). No variants or chimeras were found. Characterization of DNA revealed a novel DEL type (IVS2-2 A>G). In the lookback of the 136 transfusions with subsequent antibody follow-up, of which 13 were from DEL donors, one recipient developed anti-D. However, in this case, a competing and more likely cause of immunization was the concurrent transfusion of D+ platelets. Eleven recipients were immunized with 13 antibodies different from anti-D, of which five were anti-K. CONCLUSION: In our laboratory, serologic RhD typing was safe. We detected all D variants and only missed DEL types. In assessing the immunization risk we included a DEL donor, found previous to this study, that did immunize a recipient with anti-D. We conclude that inadvertent immunization with D antigens in our setting was rare and in the order of 1.4 in 100,000 D- transfusions.

Fetomaternal hemorrhage in women undergoing elective cesarean section.

OBJECTIVE: To investigate the degree of fetomaternal hemorrhage (FMH) caused by elective cesarean section. DESIGN: Descriptive study. SETTINGS: University Hospitals in Copenhagen, Denmark. POPULATION: Women scheduled for elective cesarean section, in the period September 2007 to January 2009, at the Department of Gynecology and Obstetrics, Hvidovre Hospital, University of Copenhagen, Denmark. METHODS: Two maternal blood samples were taken, the first before cesarean section and the second immediately after. Both samples were analyzed at the Blood Bank, Rigshospitalet, Copenhagen, for the presence of fetal red blood cells (fRBCs) using flow cytometry. FMH associated with cesarean section was defined as the difference between the volumes of fRBCs in the two samples. MAIN OUTCOME MEASURES: The frequency and volume of FMH caused by elective cesarean section. RESULTS: 207 women were included in the study. FMH was detected in 38 cases (18.4%). Of these, 22 women (10.6%) had FMH of less than 1 ml fRBCs, 13 women (6.3%) had FMH between 1 and 4 ml fRBCs, and three women (1.4%) had FMH above 4 ml fRBCs. CONCLUSIONS: We found no evidence for recommending general screening for FMH in connection with elective cesarean section, provided guidelines such as the current Danish guidelines for Rhesus prophylaxis are followed.

Only minor stem cell mobilization in head and neck irradiated patients treated with hyperbaric oxygen.

INTRODUCTION: Hyperbaric oxygen, (HBO) is used to treat several conditions including late radiation tissue injury. Previous studies have suggested that HBO mobilizes bone marrow derived stem/progenitor cells (SPC) to the peripheral blood, however possible cumulative effects were highly variable. METHODS: We have investigated a possible HBO-induced mobilization of SPCs by determining CD34+CD45dim cell numbers, as well as SPCs in general. The latter were characterized by high aldehyde dehydrogenase (ALDH) activity by use of the Aldefluor® assay. We included ten patients admitted for HBO treatment of radiation tissue injury. Six patients completed the 29-30 HBO treatment exposures. We also investigated possible HBO-induced effects on platelet activation as measured by flow cytometry and functional analyses. RESULTS: We found a weak and insignificant tendency toward mobilization of CD34+CD45dim cells after a single HBO exposure versus before. Additionally, we found an additive effect of 15 HBO exposures on the increase in CD34+CD45dim cells relative to the pre-1st-HBO values. These changes were significantly more than zero but less than a doubling. We could not demonstrate a significant effect of HBO on the content of Aldefluor® positive SPCs in peripheral blood. There was no significant effect on platelet activation overall. However, in patients with increased expression of activation markers at baseline, we found a decrease after one exposure although this was not reflected in functional tests. CONCLUSION: We found a minor statistically significant mobilizing effect of HBO treatment on the bone marrow derived stem/progenitor cell content in peripheral blood after 15 treatments (n = 10 patients), but no effect after 30 treatments (n = 6 patients). However, because of the low number of patients we cannot confidentially prove or disprove the null hypothesis. The possibility that HBO treatment reduces the number of activated platelets could not be demonstrated nor excluded.

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). CASE REPORT: 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.

Detecting fetomaternal hemorrhage by flow cytometry.

PURPOSE OF REVIEW: The aim of this review is to summarize the most recent developments in the area of detection of fetomaternal hemorrhage by flow cytometry. RECENT FINDINGS: Maternal red blood cell chimerism is readily detectable by flow cytometry. Fetal and maternal red blood cells differ in their content of fetal hemoglobin (alpha2gamma2). Fetal red blood cells contain fetal hemoglobin, and normal maternal red blood cells contain some percentage of fetal hemoglobin in a background of normal adult hemoglobin. All blood group systems with allelic differences between mother and fetus are readily applicable for detection of fetomaternal hemorrhage by fetal hemoglobin. SUMMARY: Fetal hemoglobin for detection of fetomaternal hemorrhage is an accurate clinical diagnostic procedure for investigation of anemia in fetus and newborn.

Massive antenatal fetomaternal hemorrhage: evidence for long-term survival of fetal red blood cells.

BACKGROUND: Massive fetomaternal hemorrhage (FMH) can lead to life-threatening anemia. Quantification based on flow cytometry with anti-hemoglobin F (HbF) is applicable in all cases but underestimation of large fetal bleeds has been reported. A large FMH from an ABO-compatible fetus allows an estimation of the life span of fetal red blood cells (RBCs) in the maternal circulation. CASE REPORT: The mother went to the obstetrician twice antepartum owing to symptoms assumed to be preeclampsia; that, however, was not found. She later delivered by cesarean section owing to diminished fetal movements. No fetal weight gain was observed during the last 2 weeks of pregnancy. STUDY DESIGN AND METHODS: Fetal RBCs were quantified by flow cytometry with anti-HbF, anti-Fy(a), anti-s, and anti-Jk(b) on a regular basis. RESULTS: The infant had anemia at delivery and an FMH was determined to be 314 +/- 17 mL (+/- SD) of whole blood. It is assumed that the two antenatal visits were associated with the FMH. Postpartum follow-up showed that fetal RBCs in the maternal circulation were detectable with anti-HbF up to 119 days. Quantification by flow cytometry based on anti-HbF was in agreement with quantification based on anti-Fy(a), anti-s, and anti-Jk(b), although they were less sensitive. CONCLUSION: ABO-compatible fetal RBCs from an FMH had a life span in the maternal circulation close to that of adult RBCs.