Quantification of fetomaternal hemorrhage by fluorescence microscopy is equivalent to flow cytometry

Evaluation of Automatic Blood Analyzer as Screening Method in Fetomaternal Hemorrhage

Screening of fetomaternal hemorrhage (FMH) is essential in management of fetomaternal antigen incompatibilities of blood. The objective in this study was to evaluate the ability of automatic blood analyzer (ABA) to screen FMH, also comparing this method with flow cytometry (FCM). The contents of fetal red blood cells and fetal hemoglobin were evaluated by FCM and ABA, respectively, using both blood samples of male adults laced with umbilical cord blood diluted at 1/10, 1/100, 1/1,000, and 1/10,000, or blood from puerperal women collected within 48 hours following delivery. FCM had better performance (area under curve, AUC = 0.8723) than ABA (AUC = 0.6569) in detecting fetal blood laced with blood from male adults. At a critical level of 0.5%, ABA indicated that 27.5% of puerperal women would have FMH while FCM did not detect FMH. Our results showed that ABA overestimates FMH and disagrees with FCM on indicating puerperal women with FMH. ABA is inadequate for being used to screen for or to measure FMH.

Rh(O)D immune globulin products for prevention of alloimmunization during pregnancy

PURPOSE

The pharmacologic properties of Rhesus (Rh) immune globulin (RhIG) and clinical data on its effectiveness in preventing Rh-antigen alloimmunization in pregnant women are reviewed.

SUMMARY

RhIG is a human plasma derivative that targets red blood cells (RBCs) positive for Rh(O) antigen (also called D antigen). In the United States and other countries, the widespread use of RhIG has markedly reduced the occurrence of hemolytic disease of the fetus and newborn (HDFN), a devastating condition caused by D-antigen sensitization of a pregnant woman via exposure to fetal RBCs (usually during detachment of the placenta in labor) that results in a maternal immune response leading to severe hemolysis in the fetus. Routine administration of RhIG at 26-30 weeks' gestation and again within 72 hours of delivery has been shown to be highly effective in preventing maternal Rh alloimmunization, with very low rates of D-antigen sensitization (in the range of 0-2.2%) reported in multiple studies of at-risk women. The four RhIG products currently available in the United States have common clinical indications but differ in certain attributes. Pharmacists can play an important role in guiding other clinicians on the rationale for the use of RhIG, important differences between products, and appropriate timing of RhIG therapy.

CONCLUSION

Routine administration of RhIG to women at risk for Rh alloimmunization is clinically effective and has made HDFN a rare clinical event. The available RhIG products are not the same and should be carefully reviewed to ensure that they are administered safely.

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.

Association of placental inflammation with fetomaternal hemorrhage and loss of placental mucin-1

BACKGROUND

Fetomaternal hemorrhage (FMH) poses an immediate risk to the fetus and, in case of Rhesus-immunization, to future pregnancies. Given that altered endothelial permeability is part of the pathophysiology of inflammation, in this study we investigated whether placental inflammatory processes like chorioamnionitis (ChoA) or preeclampsia (PE) lead to increased rates of FMH compared to the established risk factor of placenta previa (PP). Putative accompanying markers of trophoblastic damage were also explored.

METHODS

40 patients (14 PE; 6 ChoA; 9 PP; 11 normal controls) were evaluated for FMH using a flowcytometric test kit, which is able to quantify FMH of 0.06% fetal cells. Placental tissue samples were immunostained for human placental lactogen (hPL), human chorionic gonadotropin (hCG), and mucin-1 (MUC1). MUC1 was evaluated as a potential serum marker of FMH.

RESULTS

Patients with ChoA had a mean calculated FMH volume of 29 ml, compared to 4 ml in PE and 1 ml in PP and controls. MUC1 staining was reduced in PE and ChoA placenta samples, while elevated MUC1 serum concentration correlated positively with FMH.

CONCLUSION

Diseases of placental inflammation are associated with FMH. Placental MUC1 staining is reduced and serum concentrations are increased in cases of FMH.

Flowcytometric assessment of fetomaternal hemorrhage during external cephalic version at term

External cephalic version (ECV) at term is a safe procedure and reduces the incidence of cesarean sections for breech presentation. One of the known complications, however, is an ECV-related disruption of the placental barrier and a subsequent transfusion of fetal blood into maternal circulation. While the incidence of ECV-related fetomaternal hemorrhage (FMH) has been determined recently in a large trial using a manual Kleihauer-Betke test (KBT), questions remain on the amount of ECV-related FMH. KBT, which detects fetal red blood cells (RBC) on the basis of acidic resistance of fetal hemoglobin (HbF), is known to be a sensitive test, yet prone to procedural errors limiting its accuracy in quantifying FMH. In this study we investigated 50 patients for FMH before and after ECV, using a dual-color flow cytometric test kit with a lower limit of quantification of 0.05% fetal RBC in maternal peripheral blood. Three patients had a quantifiable increase of fetal RBC detected after ECV (0.06%; 0.08%; 0.1%). None of these subtle increments was predictable by ECV-related clinical parameters or translated into fetal compromise. Using a sensitive and accurate flow cytometric test method, our data provide further assurance to mothers on the safety of ECV at term.

Identification and quantification of fetal red blood cells in maternal blood by a dual-color flow cytometric method: evaluation of the Fetal Cell Count kit

BACKGROUND

As an alternative to the cumbersome Kleihauer-Betke test (KBT), flow cytometry represents a powerful method for the identification and quantification of fetal red blood cells (RBCs) in maternal circulation.

STUDY DESIGN AND METHODS

The aim of this study was to evaluate the Fetal Cell Count kit (IQ Products), an innovative flow cytometric method, based on the combination of antibodies directed, respectively, against fetal hemoglobin (HbF) and carbonic anhydrase (CA), a marker expressed after birth, to discriminate fetal RBCs from adult F cells containing HbF. The investigation was performed by two French laboratories that compared the data obtained by flow cytometry and KBT in 455 pregnant or just-delivered women as well as in 124 artificial mixtures containing from 0.01 to 5.00 percent cord cells.

RESULTS

The FL1/FL2 histogram allowed distinction between fetal RBCs (HbF+, CA-), F cells (HbF+, CA+), and adult RBCs (HbF-, CA+). The limits of detection and quantification were determined at 0.03 and 0.10 percent or 0.02 and 0.05 percent when analyzing 100,000 or 200,000 events, respectively. Linearity was demonstrated between 0.01 and 5.00 percent fetal cells in the mixtures (r = 0.95, p < 0.01). A good correlation between fluorescence-activated cell sorting (FACS) and KBT results was obtained with artificial mixtures (r = 0.94, p < 0.01). From the 405 Kleihauer-negative samples, none were identified as positive by FACS. Among the 50 Kleihauer-positive samples, 6 were shown not to contain fetal cells but F cells by FACS.

CONCLUSION

With this new dual-color flow cytometric method, accurate evaluation of fetomaternal hemorrhage was achieved even in the face of HbF of maternal origin.

Persistent Fetal Hemoglobin in Maternal Circulation Complicating the Diagnosis of Fetomaternal Hemorrhage

BACKGROUND

Transplacental hemorrhage can be life threatening to a fetus and has important maternal treatment implications. In contrast, hereditary persistence of fetal hemoglobin is a condition that has little consequence. The Kleihauer-Betke test, which is routinely used to document transplacental hemorrhage, will be positive in either case.

CASES

We report two cases in which maternal persistence of fetal hemoglobin was unknown and led to the erroneous diagnosis of fetomaternal hemorrhage. These cases highlight both the limitations of the Kleihauer-Betke test and the role of flow cytometry in diagnosing fetomaternal hemorrhage.

CONCLUSION

The use of flow cytometry can clarify Kleihauer-Betke test results when there is known maternal persistence of fetal hemoglobin and can more precisely quantify a fetomaternal hemorrhage for accurate Rh immune globulin dosing.

Kleihauer-Betke Testing Is Important in All Cases of Maternal Trauma

BACKGROUND

In maternal trauma, the Kleihauer-Betke (KB) test has traditionally been used to detect transplacental hemorrhage (TPH), so that Rh-negative women could receive appropriate Rh immune prophylaxis. Reasoning that the magnitude of TPH would reflect uterine injury, we evaluated Kleihauer-Betke testing as an independent predictor of preterm labor (PTL) after maternal trauma.

METHODS

Admissions to the Shock Trauma Center, University of Maryland, from January 1996 to January 2002, were reviewed. Of 30,362 trauma patients admitted, 166 were pregnant, and 93 of these underwent electronic fetal monitoring. Their records were abstracted for demographics, injury type, three separate trauma scores, documented uterine contractions, PTL (contractions with progressive cervical change), and serious perinatal complications. In 71 cases, transplacental hemorrhage was assessed by maternal KB test.

RESULTS

TPH, defined as KB-positive for greater than 0.01 mL of fetal blood in the maternal circulation, occurred in 46 women. Forty-four had documented contractions (25 had overt PTL) and 2 had no contractions. In 25 women with a negative KB test, none had uterine contractions. All patients with contractions or PTL had positive KB tests. By logistic regression, KB test result was the single risk factor associated with PTL (p < 0.001; likelihood ratio, 20.8 for positive KB test). Compared with other sites, abdominal trauma was associated more often with uterine contractions (p < 0.001), PTL (p = 0.001), and a positive KB test (p < 0.001, chi). None of the trauma scoring systems predicted PTL.

CONCLUSION

Kleihauer-Betke testing accurately predicts the risk of preterm labor after maternal trauma. Clinical assessment does not. With a negative KB test, posttrauma electronic fetal monitoring duration may be limited safely. With a positive KB test, the significant risk of PTL mandates detailed monitoring. KB testing has important advantages to all maternal trauma victims, regardless of Rh status.

Quantification of fetomaternal hemorrhage: a comparative study of the manual and automated microscopic Kleihauer-Betke tests and flow cytometry in clinical samples

OBJECTIVE

The purpose of this study was to evaluate the quantification of fetomaternal hemorrhage by the manual and automated microscopic analysis of Kleihauer-Betke stained slides and by flow cytometry.

STUDY DESIGN

Blood smears were stained and evaluated manually according to the Kleihauer-Betke test. The same slides were used for automated microscopy. In addition, blood flow cytometry was performed by anti-hemaglobin F immunostaining.

RESULTS

Fetomaternal hemorrhage >0.1% was detected in 4 patients by manual and automated Kleihauer-Betke test and by blood flow cytometry. Fetomaternal hemorrhage was absent according to all 3 methods in 13 patients; fetomaternal hemorrhage<0.1% was detected in 27 patients by either manual or automated Kleihauer-Betke test or both. Moderate agreement was observed between the manual and automated Kleihauer-Betke test (weighted kappa, 0.56; 95% CI, 0.33-0.78). Agreement between the manual Kleihauer-Betke test and blood flow cytometry was fair (weighted kappa, 0.40; 95% CI, 0.15-0.66).

CONCLUSION

Automated microscopic detection of fetal blood cells in clinical samples provides accurate quantification that is comparable to the manual Kleihauer-Betke test in both small and large fetomaternal hemorrhage. Blood flow cytometry is capable only of quantifying fetomaternal hemorrhage of >0.1%.

Macrotransfusion fœto-maternelle spontanée révélée par une diminution de la perception des mouvements actifs fœtaux

Massive fetomaternal hemorrhage is rare. Without risk factors, early diagnosis is difficult to establish. The clinical and paraclinical manifestations are not specific and depend on fetal compensatory reactions; the Kleihauer test will confirm the diagnosis. Two cases of massive fetomaternal hemorrhage preceded by decreased fetal movements are presented here. An emergency delivery by cesarean section saved one child. Despite a favorable clinical and laboratory evaluation, one fetal death could not be avoided. Early diagnosis and specialised management are essential to improve prognosis. These observations indicate that it is mandatory to carry out a Kleihauer test whenever a decrease of fetal movements is observed.