Detection of fetal red cells in fetomaternal hemorrhage using a fetal hemoglobin monoclonal antibody by flow cytometry

BACKGROUND

The laboratory determination of the level of fetal cells in maternal circulation remains an important support in the obstetrical management of women with suspected uterine trauma and in the proper dose administration of anti-D for prevention of Rh hemolytic disease of the newborn. Limitations in the sensitivity and precision of the widely used manual Kleihauer-Betke test have prompted an increased utilization of flow cytometric methods for fetal cell detection in maternal blood samples.

STUDY DESIGN AND METHODS

Murine monoclonal antibodies directed against fetal hemoglobin (HbF) were developed, conjugated to fluorescein isothiocyanate, and used in a multiparametric flow cytometric assay developed for the quantitation of fetal red cells. A rapid intracellular staining method using brief glutaraldehyde fixation and Triton X-100 permeabilization prior to monoclonal antibody incubation was developed, along with optimization of the flow cytometric analysis protocol for the analysis of 50,000 cells. The performance of the assay was assessed for linearity and precision and correlated with the Kleihauer-Betke acid elution method.

RESULTS

The anti-HbF flow cytometric method showed good correlation with the Kleihauer-Betke method (r2 = 0.86) and superior precision with a CV < 15 percent for blood samples with > 0.1 percent fetal cells. Analysis of 150 blood samples from nonpregnant adults, including individuals with elevated HbF due to hemoglobinopathies and hereditary persistence of HbF, gave a mean value of 0.02 percent fetal cells, and all results were less than 0.1 percent.

CONCLUSIONS

The anti-HbF flow cytometric method for detection of fetal cells offers a simple, reliable, and more precise alternative to the Kleihauer-Betke manual technique for the assessment of fetomaternal hemorrhage. The method has additional potential applications for the study of HbF levels or frequency of adult red cells with low levels of HbF (F cells) in individuals with hemoglobinopathies.

Fetomaternal hemorrhage following trauma

Fetomaternal hemorrhage can result from different types of trauma and may be followed by fetal anemia, fetal death, or isoimmunization. We prospectively studied the frequency and volume of fetomaternal hemorrhage, fetal well-being, abruptio placentae, and fetal outcome in 32 pregnant patients suffering recent trauma. Fetomaternal hemorrhage occurred in nine of 32 trauma patients (28%) with a mean volume of 16 ml +/- 14.3(SD). There was a statistically significant difference in the frequency and mean volume of fetomaternal hemorrhage in this group over that in gestational-age-matched controls. Neither the nature of the trauma nor the gestational age was related to the frequency or volume of fetomaternal hemorrhage. The outcome in three of the nine trauma patients who sustained fetomaternal hemorrhage was poor; fetal anemia, paroxysmal atrial tachycardia, and fetal death occurred in each one. Maternal trauma remains a significant cause of maternal and fetal morbidity and death, and the use of the Kleihauer-Betke analysis is indicated to identify fetomaternal hemorrhage. Rh-immune globulin therapy should be given to Rh-negative patients with fetomaternal hemorrhage.

Evaluation of pregnant women after blunt injury

A retrospective review of 125 pregnant women with blunt injuries admitted to a level I trauma center over a 35-month period was performed. The usefulness of three diagnostic tests, fetal ultrasound (US), external fetal monitoring (EFM), and Kleihauer-Betke (KB) tests in detecting fetal or pregnancy-associated complications was evaluated. The majority of women (77.6%) were involved in motor vehicle crashes and the mean injury Severity Score was low (4.7). The most common complications were premature uterine contractions (67%) and abruptio placentae (11%). When used together, EFM and US identified all complications. Moreover, all complications were manifest within 6 hours of admission. The KB tests had a sensitivity of 56%, a specificity of 71%, and an accuracy of 27%. We conclude that EFM and US are more useful in detecting fetal or pregnancy-associated complications after blunt injury. Monitoring can be limited to 6 hours if previous monitoring is normal. The KB test is of little use in the setting of acute trauma.

Preeclampsia-associated hepatic hemorrhage and rupture: mode of management related to maternal and perinatal outcome

This article is a critical review of the obstetric literature concerning preeclampsia-associated hepatic hemorrhage to develop guidelines conducive to optimal maternal and perinatal outcomes. An English literature search was performed for reports of hepatic hemorrhage or hepatic rupture in pregnancy during 1960 to 1997. Data were analyzed by Statmost packages using ANOVA, Chi-square, and Fisher's exact tests. One hundred forty-one patients with hepatic rupture/hemorrhage were reported. The three most common presenting findings were epigastric pain, hypertension, and shock. With rare exception, patients had evidence of preeclampsia. Diagnosis was elusive and most frequently accomplished at laparotomy. When utilized, ultrasound and computed tomography (CT) were helpful diagnostic modalities. Maternal survival was highest in the arterial embolization treatment group. Maternal and perinatal survival improved considerably during the study interval. Route of delivery did not seem to impact survival rates. It was concluded that the application of ultrasound and CT for diagnosis and the use of hepatic artery embolization for treatment of hepatic hemorrhage/rupture seem to be beneficial management options for this rare event.

Quantitation of fetal-maternal hemorrhage by flow cytometry. A simple and accurate method

A simple and objective assay was developed for the detection and quantitation of fetal-maternal hemorrhage with the use of flow cytometry. In vitro prepared control mixtures of 10%, 2%, 1%, 0.5%, 0.25%, 0.125%, and 0.06% D+ RBCs in D- RBCs were tested (8-11) different times by flow cytometry and gave mean % D+ results of 11.10%, 1.90%, 0.92%, 0.45%, 0.24%, 0.11%, and 0.05%. The coefficient of variation of preparing and testing these mixtures ranged from 11.0 to 15.9% for the 10-0.125% mixtures. Thus, flow cytometry was accurate, reproducible, and sensitive. Flow cytometry was compared with Du tests, rosette tests, and acid elution. The Du test was highly variable because it was not sensitive enough to detect a significant bleed (approximately 0.6%) in some cases and too sensitive (necessitating quantitation of an insignificant bleed) in others. The rosette test was too sensitive. Acid elution and flow cytometry results did not always agree; acid elution results were approximately twice as high as flow cytometry. The authors believe flow cytometric detection of D+ red blood cells to be more accurate than the detection of fetal hemoglobin by acid elution techniques, which is known to have poor reproducibility. Postpartum samples from 56 D- women who delivered D+ babies were tested. Fifty-two had fetal bleeds less than 0.3% by acid elution and flow cytometry; all had negative Du test results, but there were two false positive results with the use of the rosette technique. Four had significant bleeds (greater than or equal to 0.6%); in all four cases the flow cytometry results were lower than the acid elution results. The authors were able to quantitate a bleed of fetal RBCs, which were D+ only by the Du test, in a D- mother with the use of flow cytometry, and D+ RBCs in a mother whose RBCs were of the rare DVI mosaic phenotype. This would not have been possible with the use of the standard Du or rosette techniques.

Detection of fetal erythrocytes in maternal blood post partum with the fluorescence-activated cell sorter

A study was made of the frequency and amount of fetal hemorrhage into maternal blood during labor and delivery as evidenced by the number of fetal cells present in the maternal circulation immediately after spontaneous vaginal delivery. A sensitive, indirect immunofluorescence was used with fluorescence-activated cell sorter analysis of erythrocytes. All of the 16 Rh-negative mothers studied after vaginal delivery of Rh-positive infants had circulating Rh-positive cells. The mean Rh-positive to Rh-negative erythrocyte ratio was 1:14, 100 in maternal blood, which corresponds to a mean fetal hemorrhage of 156 microliters. The test described is sufficiently sensitive to be used for the study of primary Rh isoimmunization and could be clinically applicable for antepartum screening to determine which patients require Rh immune globulin treatment before delivery.

Use of Rh immune globulin: ASCP practice parameter. American Society of Clinical Pathologists

The use of Rh immune globulin (RhIG) has dramatically decreased the incidence of hemolytic disease of the fetus and newborn resulting from the production of anti-D by an Rh-negative woman. However, despite the widespread use of RhIG, instances of Rh immunization continue to occur, most likely through failure to administer RhIG when indicated or in the appropriate dose. This utilization gap can be closed only through continued active surveillance by health care providers. The following report summarizes recommendations for the administration of RhIG, the dose required in various circumstances, prenatal and postnatal serologic testing of the obstetric patient, and the methods used to determine the degree of fetomaternal hemorrhage or the amount of Rh-positive RBCs in the circulation.

Clinical high-risk designation does not predict excess fetal-maternal hemorrhage

During a 5-year period, an enzyme-linked antiglobulin test was used to screen and quantitate fetal-maternal hemorrhage in 789 consecutive D-negative mothers who were delivered of D-positive babies. Six hundred seventy-two patients (85.2%) had no detectable fetal-maternal hemorrhage, and 117 patients (14.8%) had a detectable fetal-maternal hemorrhage. Eight of the 789 (1%) had a fetal-maternal hemorrhage greater than 30 ml and required more than one vial of Rh immune globulin. Two patients with fetal-maternal hemorrhage of 29 and 30 ml also received additional Rh immune globulin. Each case was reviewed for the presence of high-risk features that are thought to predict patients at risk for fetal-maternal hemorrhage. Patients having a cesarean section or complicated vaginal delivery were considered to be in a group at high risk for fetal-maternal hemorrhage, while those with a spontaneous vaginal delivery were considered not to be at risk for fetal-maternal hemorrhage. Thirty-two of 237 patients (13.5%) in the risk group and 82 of 552 patients (15.3%) in the group not at risk had detectable fetal-maternal hemorrhage. The incidence of fetal-maternal hemorrhage for these two groups was not statistically different (p greater than 0.50 by chi 2 analysis). If only patients in the risk group had been screened for fetal-maternal hemorrhage, then five of 10 (50%) who required more than one vial of Rh immune globulin would have been undertreated and at risk for developing anti-D antibodies. In addition, newborn birth weight, Apgar scores, and hematocrits were examined for 13 cases of fetal-maternal hemorrhage of greater than or equal to 21 ml, and none of these characteristics could be used to predict patients at risk for fetal-maternal hemorrhage. Therefore, no maternal or newborn characteristics could be identified that would reliably predict patients at risk for fetal-maternal hemorrhage. We conclude that all D-negative patients with D-positive babies should continue to be screened for fetal-maternal hemorrhage to identify those patients requiring more than one vial of Rh immune globulin.

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.

Multicenter clinical experience with flow cytometric method for fetomaternal hemorrhage detection

BACKGROUND

Enumeration of fetal red blood cells (RBCs) is important in the management of fetomaternal hemorrhage (FMH), particularly in situations of Rh incompatibility.

METHODS

We evaluated results from three institutions using the flow cytometric method (FCM) to detect fetal RBCs based on the anti-hemoglobin F (HbF) monoclonal antibody method.

RESULTS

During 1997-2001, 69 of 1248 patients (5.5%) had measurable fetal erythrocytes (RBCs) in maternal blood. Only 21 patients (1.7%) had more than 30 mL of fetal blood detected in maternal blood. Of the 11 patients with large FMH and clinical follow-up, 7 had fetal demise (64%). In positive samples, significant differences were found in the fluorescence intensity (FI) of anti-HbF antibody staining between HbF-negative erythrocytes (HbF-) and adult HbF containing erythrocytes (F cells; 4 +/- 0 versus 57 +/- 9 linear mean channels [LMC]; P < 0.001) and between HbF-cells and fetal RBCs (4 +/- 0 versus 433 +/- 136 LMC; P < 0.001). In addition, significant differences were observed in forward light scatter intensity between HbF-cells and fetal RBCs (298 +/- 15 versus 355 +/- 68 LMC, P = 0.03). The transportability of the test is also addressed by comparing results from two other laboratories. The experience of our three laboratories, as well as the results from the recently reinitiated College of American Pathologists survey, which compares FCM and manual methods, clearly documents the superiority of the FCM test over the manual Kleihauer-Betke (KB) test.

CONCLUSIONS

The FCM is a simpler, more objective, and more precise alternative to the KB method in clinical testing. The high mortality rate associated with large FMH and therapeutic implications of these results should give laboratories motivation to abandon the KB method with more robust FCM to detect FMH.

Quantitation of transplacental haemorrhage

On four occasions over a period of four years samples of adult blood to which known amounts of fetal blood had been added were distributed to 8-12 different laboratories taking part in clinical trials organized by an M.R.C. Working Party. Estimates were made of the proportion of fetal: adult red cells in the samples after preparing films by the acid-elution method. When the proportion of fetal: adult red cells was less than about 1:10,000, the highest and lowest estimates were separated by a factor of about 10. However, when the number of cells present was between about 1:100 and 1:1,000, most results were between half and twice the true number of cells present.It is pointed out that since fetal red cells are approximately 30% larger than adult red cells, and since only about 90% of fetal cells stain darkly in the acid-elution method, estimates of the proportion of darkly-staining cells in a film underestimate the volume of fetal red cells present by about one-third. A simple formula is proposed which corrects for this factor and which gives an estimate of the total volume of fetal red cells present, deduced from the ratio of fetal: adult red cells and assuming a maternal red cell volume at term of 1,800 ml.A method of screening blood films is suggested which, firstly, endeavours to standardize the density of adult red cells on films, and, secondly, takes into account the Poisson distribution. Thus limits are set for the number of fetal red cells which can be seen in scanning a given number of adult cells before the suspicion is aroused that a transplacental haemorrhage exceeding a certain amount is present.It is emphasized that the density of adult red cells on blood films varies very widely, and unless the cell density and the size of the low-power field are defined the practice of deducing the extent of transplacental haemorrhage from the number of fetal red cells seen per low-power field may lead to large errors.

Use of a directly conjugated monoclonal anti-D (BRAD-3) for quantification of fetomaternal hemorrhage by flow cytometry

BACKGROUND

Determination of the volume of fetal D-positive cells in the circulation of D-negative women after delivery is carried out to determine whether additional prophylactic anti-D should be given to the mother. Although the Kleihauer-Betke test is still widely used to calculate the fetomaternal hemorrhage, increasing use is being made of flow cytometry.

STUDY DESIGN AND METHODS

A conjugated monoclonal anti-D was prepared by labeling purified BRAD-3 (IgG3) with fluorescein isothiocyanate (FITC-BRAD-3). This reagent was used to label D-positive red cells by a one-step procedure: 5 microL of washed cells were incubated with 50 microL of FITC-BRAD-3 (50 micrograms/mL) at 37 degrees C for 30 minutes; then the cells were washed and 500,000 events were analyzed by flow cytometry.

RESULTS

The FITC-BRAD-3 reagent effectively labeled D-positive cells. The percentage of D-positive cells in mixtures containing more than 0.04 percent D-positive cells in D-negative cells was accurately determined by using this reagent and flow cytometry. Although the Kleihauer-Betke test was more accurate than this one-step flow cytometric method at quantifying fetomaternal hemorrhage of < 1 mL, the flow cytometric method was more accurate in the 1- to 7-mL fetomaternal hemorrhage range of 1 to 7 mL (whole-blood equivalents). Analysis of 175 clinical samples for fetomaternal hemorrhage gave consistent quantification results with the three methods used: the Kleihauer-Betke test, flow cytometry with FITC-BRAD-3, and flow cytometry with polyclonal anti-D followed by FITC-anti-IgG.

CONCLUSION

Labeling of samples with FITC-BRAD-3 was simple and rapid. By flow cytometric analysis, good separation of D-positive from D-negative cells was obtained, and fetomaternal hemorrhage of > 1 mL was quantified accurately.

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.

Cell-free fetal DNA levels in maternal plasma after elective first-trimester termination of pregnancy

OBJECTIVE

To determine if first-trimester elective termination of pregnancy affects cell-free fetal DNA (fDNA) levels in maternal plasma.

DESIGN

Prospective cohort study.

SETTING

Clinical and academic research centers.

PATIENT(S)

One hundred thirty-four women who underwent first-trimester elective termination procedures.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Real-time polymerase chain reaction (PCR) amplification and measurement of DYS1, a Y-chromosome sequence, was used as a marker of fDNA.

RESULT(S)

We detected fDNA in pretermination samples from 27 out of 71 patients in the surgical arm, and 29 out of 63 patients in the medical arm. Based on confirmation of male gender in placental tissue, the sensitivity of fDNA detection is 92.6%. We detected fDNA as early as 32 days of gestation, which increased 4.2 genome equivalents/mL/week. In the surgical arm, the mean level of posttermination fDNA, adjusted for the clearance of fDNA in maternal blood, was higher than projected based on an expected increase with gestational age. In the medical arm, six patients had increased fDNA levels up to 11 days following termination.

CONCLUSION(S)

We found that fDNA can be reliably quantified in the early first trimester; fDNA elevation that occurs shortly after surgical termination may reflect fetomaternal hemorrhage or destruction of trophoblastic villi. Continued elevation of fDNA for several days may occur following medical termination.

Identification of nucleated red blood cells in maternal circulation: a second step in screening for fetal aneuploidies and pregnancy complications

BACKGROUND

Identification of fetal nucleated red blood cells (NRBCs) in maternal circulation can facilitate non-invasive prenatal diagnosis, but technical difficulties still exist. An increase in the number of circulating NRBCs, however, could indicate fetal aneuploidies or pregnancy complications.

MATERIALS AND METHODS

The number of NRBCs was determined from 20 mL peripheral blood in 351 women in the second trimester of pregnancy after isolation by magnetic cell sorting (MACS) with anti-CD71 antibody and identification with May-Grunwald/Giemsa staining.

RESULTS

An average of eight NRBCs (range 1-12) were identified among 282 women with chromosomally normal fetuses. In cases known to carry aneuploid fetuses the mean number was 35 (range 7-113), but when the fetus had trisomy 21 (n = 17) an average of 71 NRBCs were identified. Among 26 carriers of beta-thalassemia, 42 NRBCs (range 22-158) were isolated. In pregnancies with abnormal Doppler findings in both uterine arteries (n = 20), 15 NRBCs (range 2-75) were isolated.

CONCLUSION

Determining the number of NRBCs in maternal circulation could represent an additional screening step for fetal aneuploidies, as long as the anemic status of the mother is taken into consideration. However, more cases with abnormal Doppler results must be investigated before this test is used for in the prediction of pregnancy complications.

Detecting fetomaternal hemorrhage: a comparison of five methods

Appropriate postpartum administration of Rh immune globulin relies on sensitive detection and accurate quantitation of fetomaternal hemorrhage (FMH). Recently, the microscopic Du test (micro Du) enhanced with polyethylene glycol (PEG Du) and flow cytometry (FC) have been advocated for this purpose. Three qualitative methods (micro Du, rosette test, and PEG Du) and two quantitative methods (acid elution and FC) for assessing FMH were evaluated with particular attention given to PEG Du and FC. In vitro studies comprised 10 series of dilutions of D+ cord cells in D- adult cells to yield D+ cell concentrations of 0.06, 0.12, 0.25, 0.50, 0.75, 1.0, and 2.0 percent. Additionally, 26 postpartum samples were tested. Of the qualitative techniques, the micro Du test was the least sensitive with 20 percent false-negative results occurring at 0.5 percent fetal cells. The PEG Du test was only slightly more sensitive and offered no clinical advantage. The rosette test was the most sensitive, consistently detecting fetal cells at concentrations of 0.25 percent or greater. FC and acid elution showed similar results, with good correlation obtained between measured and expected quantities of fetal cells (r = 0.99 and 0.96, respectively). One of 26 postpartum samples was positive by all screening techniques; acid elution and FC detected 0.3-percent concentrations of fetal cells and 0.17-percent concentrations of D+ cells, respectively. Although acid elution is a more commonly used method for quantitating FMH, FC offers an acceptable alternative that is capable of analyzing large numbers of cells with objectivity and reproducibility.

The Kleihauer technique: an accurate method of quantifying fetomaternal haemorrhage?

Blood was taken from 100 consecutive asymptomatic women at 17 to 18 weeks of pregnancy for Kleihauer testing. When a proportion of these slides were assessed at a different hospital there was agreement in only 46%. When the number of fetal cells were quantified there were differences of over 500%. These results show a large inter-observer and inter-hospital variation in interpreting Kleihauer slides. If these investigations are to be performed, it is essential that clinicians can rely on the results. There is a need for quality control measures and audit so that laboratories can rectify any deficiencies in their techniques.

Feto-maternal haemorrhage as a cause of fetal morbidity and mortality

Massive feto-maternal haemorrhage is a cause of significant fetal morbidity and mortality, but is often overlooked because screening for fetal erythrocytes in the maternal circulation has not been a routine procedure in stillbirths, fetal distress or neonatal anaemia; there are few recognized clinical symptoms or signs, or histopathological features. This report covers three cases. A screening blood test in the last month of pregnancy could be of value in detecting feto-maternal haemorrhage before irreversible damage to the fetus occurs.

Flow cytometry in diagnosis and management of large fetomaternal haemorrhage

AIMS

To evaluate an indirect immunofluorescence flow cytometry technique in a series of patients with large fetomaternal haemorrhage (FMH).

METHODS

Patient samples identified by Kleihauer testing in local laboratories as having FMH > 4 ml were sent for flow cytometric analysis. In a proportion of cases the mothers received anti-D immunoglobulin prophylaxis according to the flow cytometer estimate of FMH volume.

RESULTS

Forty three cases of FMH were studied prospectively. The correlation between Kleihauer and flow cytometry results was poor. In 38 (88%) cases the size of FMH quantitated by flow cytometry was lower than that estimated using the Kleihauer technique. In 13 (30%) cases no Rh D immunoglobulin positive cells were detected by flow cytometry. Centralised review of the original Kleihauer films using a calibrated microscope resulted in improved, but still suboptimal correlation with flow cytometry results. In 15 cases anti-D immunoglobulin was given according to the flow cytometer estimation of FMH size, resulting in a 58% reduction in the amount of anti-D immunoglobulin given. None of the patients were immunised when tested six months later.

CONCLUSIONS

Flow cytometry is helpful for the accurate quantitation and management of patients with large FMH and in cases where the presence of maternal haemoglobin F containing cells renders the Kleihauer technique inaccurate. Worthwhile reductions in the use of anti-D immunoglobulin can be achieved.

Fetomaternal hemorrhage in threatened abortion

In this study, we compared the incidence of fetomaternal hemorrhage between patients with threatened abortion and a control population of similar gestational age. The study population comprised pregnant patients at less than 20 weeks' gestation who presented to our emergency room with a history of vaginal bleeding without cervical dilatation or passage of tissue. The control population consisted of women presenting for elective pregnancy termination; they were excluded from the study if they gave a history of any antepartum bleeding. The amount of fetomaternal hemorrhage was evaluated using the Kleihauer-Betke acid elution assay. A positive result in our laboratory, as determined by a nonpregnant control group, was a value of 0.07% or more fetal cells. Using this criterion, 11% of the study population had a positive Kleihauer-Betke test, compared with 4% in the pregnant control group. Rho(D) immunoglobulin may be indicated in Rho(D)-negative patients who present with threatened abortion.

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.

Large fetomaternal hemorrhage: clinical presentation and outcome

AIM

To evaluate the incidence and outcome of all neonates with demonstrated fetomaternal hemorrhages > or = 20 ml and to assess possible predictors of large fetomaternal hemorrhage and outcome.

METHODS

Retrospective data analysis 1987-2000. Clinical data included antenatal events, method of delivery, condition at birth, hematology results, treatment and outcome.

RESULTS

Sixteen infants were identified and treated for fetomaternal hemorrhage. Adverse outcome occurred in five infants (31%). Outcome was predicted by postnatal presentation and initial hemoglobin.

CONCLUSION

Adverse outcome amongst neonates with large fetomaternal hemorrhage is high. Outcome is better predicted by initial hemoglobin than volume of hemorrhage as per the Kleihauer test.