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

Rhesus D Prophylaxis: When and Why We Give Rhesus D Immunoglobulin

Importance

Hemolytic disease of the fetus and newborn (HDFN) is caused by maternal alloantibodies to fetal red blood cells and is associated with significant fetal and neonatal morbidity and mortality. Rhesus D antigen (RhD)-mediated HDFN is the only preventable cause of alloimmunization in pregnancy. Widespread utilization of RhD prophylaxis reduces the risk of RhD-mediated alloimmunization from 17% to <1% in at-risk pregnancies, although RhD-mediated HDFN still occurs.

Objective

To emphasize significance of RhD prophylaxis, outline current guideline-directed indications for administration, provide clarification in areas of uncertainty regarding prophylaxis administration, and review key concepts relevant to patient education and shared decision-making.

Evidence Acquisition

PubMed and Google Scholar literature search.

Results

Data over several decades have shown implementation of prenatal and postpartum RhD prophylaxis has significantly reduced incidence and morbidity of RhD-mediated HDFN. Most international guidelines recommend routine prophylaxis of Rh-negative mothers in the second trimester and peripartum, with additional prophylaxis following certain high-risk events. Recent shortages in RhD immunoglobulin (RhDIg) and new methods to determine fetal blood type have prompted renewed debate regarding criteria for prophylaxis during the first trimester.

Conclusion

Understanding indications for administration of RhD prophylaxis is essential for preventing RhD alloimmunization. Although uncertainty remains in some clinical scenarios, prophylaxis is strongly recommended in Rh-negative mothers in the second trimester, following events high-risk for sensitization in pregnancy, and postpartum.

Relevance

In this review, the etiology of alloimmunization and indications for RhDIg prophylaxis, current society recommendations, and areas of debate are summarized and discussed.

Risk factors for RhD immunisation in a high coverage prevention programme of antenatal and postnatal RhIg: a nationwide cohort study

OBJECTIVE

To evaluate which risk factors for RhD immunisation remain, despite adequate routine antenatal and postnatal RhIg prophylaxis (1000 IU RhIg) and additional administration of RhIg. The second objective was assessment of the current prevalence of RhD immunisations.

DESIGN

Prospective cohort study.

SETTING

The Netherlands.

POPULATION

Two-year nationwide cohort of alloimmunised RhD-negative women.

METHODS

RhD-negative women in their first RhD immunised pregnancy were included for risk factor analysis. We compared risk factors for RhD immunisation, occurring either in the previous non-immunised pregnancy or in the index pregnancy, with national population data derived from the Dutch perinatal registration (Perined).

RESULTS

In the 2-year cohort, data from 193 women were eligible for analysis. Significant risk factors in women previously experiencing a pregnancy of an RhD-positive child (n = 113) were: caesarean section (CS) (OR 1.7, 95% CI 1.1-2.6), perinatal death (OR 3.5, 95% CI 1.1-10.9), gestational age >42 weeks (OR 6.1, 95% CI 2.2-16.6), postnatal bleeding (>1000 ml) (OR 2.0, 95% CI 1.1-3.6), manual removal of the placenta (MRP) (OR 4.3, 95% CI 2.0-9.3); these factors often occurred in combination. The miscarriage rate was significantly higher than in the Dutch population (35% versus 12.-5%, P < 0.001).

CONCLUSION

Complicated deliveries, including cases of major bleeding and surgical interventions (CS, MRP), must be recognised as a risk factor, requiring estimation of fetomaternal haemorrhage volume and adjustment of RhIg dosing. The higher miscarriage rate suggests that existing RhIg protocols need adjustment or better compliance.

Accurate quantitation of D+ fetomaternal hemorrhage by flow cytometry using a novel reagent to eliminate granulocytes from analysis

BACKGROUND

Quantitation of fetomaternal hemorrhage (FMH) is performed to determine the dose of prophylactic anti-D (RhIG) required to prevent D immunization of D- women. Flow cytometry (FC) is the most accurate method. However, maternal white blood cells (WBCs) can give high background by binding anti-D nonspecifically, compromising accuracy.

STUDY DESIGN AND METHODS

Maternal blood samples (69) were sent for FC quantitation of FMH after positive Kleihauer-Betke test (KBT) analysis and RhIG administration. Reagents used were BRAD-3-fluorescein isothiocyanate (FITC; anti-D), AEVZ5.3-FITC (anti-varicella zoster [anti-VZ], negative control), anti-fetal hemoglobin (HbF)-FITC, blended two-color reagents, BRAD-3-FITC/anti-CD45-phycoerythrin (PE; anti-D/L), and BRAD-3-FITC/anti-CD66b-PE (anti-D/G). PE-positive WBCs were eliminated from analysis by gating. Full blood counts were performed on maternal samples and female donors.

RESULTS

Elevated numbers of neutrophils were present in 80% of patients. Red blood cell (RBC) indices varied widely in maternal blood. D+ FMH values obtained with anti-D/L, anti-D/G, and anti-HbF-FITC were very similar (r = 0.99, p < 0.001). Correlation between KBT and anti-HbF-FITC FMH results was low (r = 0.716). Inaccurate FMH quantitation using the current method (anti-D minus anti-VZ) occurred with 71% samples having less than 15 mL of D+ FMH (RBCs) and insufficient RhIG calculated for 9%. Using two-color reagents and anti-HbF-FITC, approximately 30% patients had elevated F cells, 26% had no fetal cells, 6% had D- FMH, 26% had 4 to 15 mL of D+ FMH, and 12% patients had more than 15 mL of D+ FMH (RBCs) requiring more than 300 μg of RhIG.

CONCLUSION

Without accurate quantitation of D+ FMH by FC, some women would receive inappropriate or inadequate anti-D prophylaxis. The latter may be at risk of immunization leading to hemolytic disease of the newborn.

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.

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.

Prevention of RhD alloimmunization in RhD negative women

BACKGROUND

Despite the introduction of anti-D prophylaxis into clinical practice, RhD alloimmunization still presents a problem to date. The actual incidence of RhD alloimmunization in pregnant women remains unknown in most countries. Anti-D immunoglobulin is administered to RhD negative women at a fixed dose and in much greater amounts than is actually necessary. On the other hand, it is not possible to diagnose cases where greater doses are needed. To optimize the prevention of RhD alloimmunization in RhD negative women, it is important to diagnose conditions that lead to fetomaternal hemorrhage (FMH), precisely determine the volume and subsequently administer the appropriate dose of anti-D immunoglobulin. The possibility to accurately detect FMH and precisely determine its volume would enable more effective and less costly prevention of RhD alloimmunization. Anti-D immunoglobulin could be administered only in indicated cases and only in doses essentially necessary for prevention of RhD alloimmunization.

METHODS AND RESULTS

The Cochrane and UpToDate databases of systematic reviews, as well as national guidelines, were reviewed.

CONCLUSIONS

Due to the medical significance and indispensable economic costs associated with prevention of RhD alloimmunization, it would be appropriate to establish exact methodical guidelines. The text itself should be limited to a list of potentially sensitising events during which anti-D immunoglobulin should be administered to RhD negative women if anti-D antibodies are not already present. Following each potentially sensitising event, the minimal dose of anti-D immunoglobulin necessary for prevention of RhD alloimmunization should be determined. After 20 weeks of gestation, the volume of FMH should also be determined to specify the necessary dose of anti-D immunoglobulin.

Risk factors for RhD immunisation despite antenatal and postnatal anti-D prophylaxis

OBJECTIVE

To identify risk factors for Rhesus D (RhD) immunisation in pregnancy, despite adequate antenatal and postnatal anti-D prophylaxis in the previous pregnancy. To generate evidence for improved primary prevention by extra administration of anti-D Ig in the presence of a risk factor.

DESIGN

Case-control study.

SETTING

Nation-wide evaluation of the Dutch antenatal anti-D-prophylaxis programme.

POPULATION

CASES

42 RhD-immunised parae-1, recognised by first-trimester routine red cell antibody screening in their current pregnancy, who received antenatal and postnatal anti-D Ig prophylaxis (gifts of 1000 iu) in their first pregnancy.

CONTROLS

339 parae-1 without red cell antibodies.

METHODS

Data were collected via obstetric care workers and/or personal interviews with women.

MAIN OUTCOME MEASURE

Significant risk factors for RhD immunisation in multivariate analysis.

RESULTS

Independent risk factors were non-spontaneous delivery (assisted vaginal delivery or caesarean section) (OR 2.23; 95% CI:1.04-4.74), postmaturity (>or=42 weeks of completed gestation: OR 3.07; 95% CI:1.02-9.02), pregnancy-related red blood cell transfusion (OR 3.51; 95% CI:0.97-12.7 and age (OR 0.89/year; 95% CI:0.80-0.98). In 43% of cases, none of the categorical risk factors was present.

CONCLUSIONS

In at least half of the failures of anti-D Ig prophylaxis, a condition related to increased fetomaternal haemorrhage (FMH) and/or insufficient anti-D Ig levels was observed. Hence, RhD immunisation may be further reduced by strict compliance to guidelines concerning determination of FMH and accordingly adjusted anti-D Ig prophylaxis, or by routine administration of extra anti-D Ig after a non-spontaneous delivery and/or a complicated or prolonged third stage of labour.

Inaccurate doses of R immune globulin after rh-incompatible fetomaternal hemorrhage: survey of laboratory practice

CONTEXT

Rh(D)-negative women with a large fetomaternal hemorrhage (FMH) from an Rh(D)-positive fetus are at risk for anti-D alloimmunization if they do not receive adequate Rh immune globulin (RhIG). Determination of the adequate RhIG dose for these women is a critical laboratory procedure for protecting their future Rh(D)-positive children.

OBJECTIVE

To determine how often laboratories recommended an inaccurate dose of RhIG for excess FMH.

DESIGN

Nearly 1600 laboratories using the College of American Pathologists' proficiency testing for fetal red blood cell detection were surveyed to determine (1) their calculation method and (2) the number of RhIG doses recommended for a survey specimen, based on their measured percentage of fetal red blood cells. We surveyed nearly 1450 laboratories for their accuracy in determining RhIG dose, using 2 common calculation methods we provided.

RESULTS

The AABB Technical Manual method was used by 67% of responding laboratories. However, 20.7% of laboratories using this method would have recommended an inaccurate dose of RhIG--11.5% too much and 9.2% too little--for the level of FMH reported in the survey specimen. If all laboratories had used the common recommendation of 300 microg/30 mL of fetal blood present, 2% would have recommended RhIG doses too low for the volume of FMH they measured. In 3 of the 4 calculation exercises we provided, 20% to 30% of laboratories underestimated the necessary dose of RhIG.

CONCLUSIONS

Based on our surveys, some mothers with excess FMH may be receiving inaccurate doses of RhIG. Laboratories performing quantification of FMH should review their procedures and training for calculating RhIG dosage.

Risk factors for the presence of non-rhesus D red blood cell antibodies in pregnancy

OBJECTIVE

To identify risk factors for the presence of non-rhesus D (RhD) red blood cell (RBC) antibodies in pregnancy. To generate evidence for subgroup RBC antibody screening and for primary prevention by extended matching of transfusions in women <45 years.

DESIGN

Case-control study.

SETTING

Nationwide evaluation of screening programme for non-RhD RBC antibodies.

POPULATION

CASES

consecutive pregnancies (n=900) with non-RhD immunisation identified from 1 September 2002 to 1 June 2003 and 1 October 2003 to 1 July 2004; controls (n=968): matched for obstetric caregiver and gestational age.

METHODS

Data collection from the medical records and/or from the respondents by a structured phone interview.

MAIN OUTCOME MEASURES

Significant risk factors for non-RhD immunisation in multivariate analysis.

RESULTS

Significant independent risk factors: history of RBC transfusion (OR 16.7; 95% CI: 11.4-24.6), parity (para-1 versus para-0: OR 1.3; 95% CI: 1.0-1.7; para-2 versus para-0: OR 1.4; 95% CI: 1.0-2.0; para >2 versus para-0: OR 3.2; 95% CI: 1.8-5.8), haematological disease (OR 2.1; 95% CI: 1.0-4.2), history of major surgery (OR 1.4; 95% CI: 1.1-1.8). For the clinically most important antibodies, anti-K, anti-c and other Rh-nonD-antibodies RBC transfusion was the most important risk factor, especially for anti-K (OR 96.4; 95%-CI: 56.6-164.1); 83% of the K-sensitised women had a history of RBC transfusion. Pregnancy-related risk factors were a prior male child (OR 1.7; 95% CI: 1.2-2.3) and caesarean section (OR 1.7; 95% CI: 1.1-2.7).

CONCLUSIONS

RBC transfusion is by far the most important independent risk factor for non-RhD immunisation in pregnancy, followed by parity, major surgery and haematological disease. Pregnancy-related risk factors are a prior male child and caesarean section. Subgroup screening for RBC antibodies, with exclusion of RhD-positive para-0 without clinical risk factors, is to be considered. This approach will be equally sensitive in detecting severe Haemolytic Disease of the Fetus and Newborn compared with the present RBC antibody screening programme without preselection. Primary prevention by extending preventive matching of transfusions in women younger than 45 will prevent more than 50% of pregnancy immunisations.

Feto - maternal haemorrhage in parturients: Incidence and its determinants

This prospective study of parturients at a tertiary health institution in south-western Nigeria aims to identify the incidence, severity and obstetric factors predisposing to feto - maternal haemorrhage (FMH) in our population. The exclusion criteria were haemoglobinopathy and patient's refusal of consent to participate in the study. The prepared slide was processed as in the acid elution test described by Kleihauer - Betke. The FMH was calculated using Mollison formula (Mollison 1972). Baseline data included maternal biodata, blood group, RhD and haemoglobin electrophoresis, route/mode of delivery, duration of labour, obstetric interventions, fetal blood group and birth weight. Data generated were analysed with Statistical Package for Social Scientists (SPSS) version 11 software. Frequency tables, cross-tabulations and correlations were performed. Pearson's correlation was applied to continuous variables, while Spearman's correlation was utilised for discrete variables. Level of statistical significance was set at p < 0.05. A total of 163 parturients were studied, of which eight were multifetal gestations. There were no significant differences in maternal age, parity, estimated gestational age at delivery and birth weight, in both groups of parturients with and without FMH. A total of 17 parturients (10.43%), four of which were multifetal gestations (2.45%), had demonstrable FMH. Large FMH (>15 ml fetal cells) were noted in 10 (6.14%) parturients, of which, four were RhD-negative mothers. A total of 9.8% and 11.5% parturients in the vaginal and caesarean delivery groups, respectively, had significant FMH (p = 0.736). Incidence of large FMH was similar with each of the routes of delivery. Antepartum complications of pregnancy, delivery manoeuvres and episiotomy were not significant determinants of FMH. Multiple gestations, fetal birth weight and complications in labour were significantly associated with risk of FMH. Risk-based approach to management, in RhD negative pregnant women, might lead to under-treatment, with attendant increased incidence of isoimmunisation. At least in all RhD-negative women, the cord blood should be tested to determine the baby's blood group and if RhD-positive, Kleihauer - Betke test should be done to determine the degree of FMH and anti-D immunoglobulin dose administered appropriately. Further studies are necessary to establish the determinants/risk factors for FMH.

[Evaluation of fetomaternal hemorrhage in postpartum patients with indication for administration of anti-D immunoglobulin]

This study evaluated fetomaternal hemorrhage (FMH) in 343 postpartum patients who required prophylaxis of Rh alloimmunization with anti-D immunoglobulin. The rosette test was applied to screen for patients needing quantitative determination of fetal blood transferred from the maternal circulation, which was then measured by the Kleihauer-Betke test (K-B). The rosette test was positive in 22 cases (6.4%). In five of these cases, K-B did not show fetomaternal hemorrhage (a 1.45% false-positive rate for the rosette test), and in one case the test was inconclusive. There were 8 cases with FMH < 10 ml (2.3%), 6 cases with FMH from 10 to 30 ml (1.7%), and two cases with FMH > 30 ml (0.58%), requiring a supplementary dose of anti-D. The study concludes that following the rosette test, additional evaluation of FMH using a quantitative test was unnecessary in 93.6% of the cases.

The Incidence of Large Fetomaternal Hemorrhage and the Kleihauer-Betke Test

OBJECTIVE

To assess the frequency of large fetomaternal hemorrhage and to estimate its incidence in cesarean compared with vaginal deliveries.

METHODS

In this prospective cohort study, the study group was composed of 313 women who underwent cesarean delivery. Control subjects were 253 women who delivered vaginally and were matched for age, parity, ethnic origin, and gestational age. Ninety-six pregnant women at term, but before delivery (prelabor group), were also included to determine whether delivery itself is the cause of fetomaternal hemorrhage. Fetomaternal hemorrhage was measured by using the Kleihauer-Betke test.

RESULTS

Twenty women (6.4%) in the study group and 17 (6.7%) in the control group had a large fetomaternal hemorrhage (Kleihauer-Betke test > 0.4%). Five women (5.2%) in the prelabor group had a large fetomaternal hemorrhage. The differences were not significant. A large fetomaternal hemorrhage occurred in 14 of 146 (9.6%) women who underwent emergency cesarean, compared with 6 of 167 (3.5%) who delivered by elective cesarean (P = .04). In deliveries complicated by oligohydramnios, cord around the neck, or low birth weight, a higher rate of large fetomaternal hemorrhage was seen.

CONCLUSION

Our results indicate a rate of large fetomaternal hemorrhage that is substantially higher than previously reported, with no difference between vaginal and cesarean deliveries. This may reflect inaccuracies with the current method used to estimate the degree of fetomaternal hemorrhage.

Prevention and management of RhD isoimmunization

An Rh-negative woman is at risk for developing Rh isoimmunization upon exposure to RhD antigens from her Rh-positive baby through fetal-maternal hemorrhage. The incidence of Rh isoimmunization and fetal hemolytic disease has decreased substantially since Rh immune globulin was introduced in 1968. When RhD sensitization does occur, careful follow-up of these mothers and judicious intervention can result in good outcomes for most pregnancies. Both Doppler assessment of middle cerebral artery peak systolic velocity and spectral analysis of amniotic fluid at 450 nm (DeltaOD 450) are useful in the diagnosis and management of fetal anemia.

Prevention of Rh alloimmunization

OBJECTIVE

To provide guidelines on use of anti-D prophylaxis to optimize prevention of rhesus (Rh) alloimmunization in Canadian women.

OUTCOMES

Decreased incidence of Rh alloimmunization and minimized practice variation with regards to immunoprophylaxis strategies.

EVIDENCE

The Cochrane Library and MEDLINE were searched for English-language articles from 1968 to 2001, relating to the prevention of Rh alloimmunization. Search terms included: Rho(D) immune globulin, Rh iso- or allo-immunization, anti-D, anti-Rh, WinRho, Rhogam, and pregnancy. Additional publications were identified from the bibliographies of these articles. All study types were reviewed. Randomized controlled trials were considered evidence of highest quality, followed by cohort studies. Key individual studies on which the principal recommendations are based are referenced. Supporting data for each recommendation is briefly summarized with evaluative comments and referenced.

VALUES

The evidence collected was reviewed by the Maternal-Fetal Medicine and Genetics Committees of the Society of Obstetricians and Gynaecologists of Canada (SOGC) and quantified using the Evaluation of Evidence guidelines developed by the Canadian Task Force on the Periodic Health Exam.

RECOMMENDATIONS

1. Anti-D Ig 300 microg IM or IV should be given within 72 hours of delivery to a postpartum nonsensitized Rh-negative woman delivering an Rh-positive infant. Additional anti-D Ig may be required for fetomaternal hemorrhage (FMH) greater than 15 mL of fetal red blood cells (about 30 mL of fetal blood). Alternatively, anti-D Ig 120 microg IM or IV may be given within 72 hours of delivery, with testing and additional anti-D Ig given for FMH over 6 mL of fetal red blood cells (12 mL fetal blood). (I-A) 2. If anti-D is not given within 72 hours of delivery or other potentially sensitizing event, anti-D should be given as soon as the need is recognized, for up to 28 days after delivery or other potentially sensitizing event. (III-B) 3. There is poor evidence regarding inclusion or exclusion of routine testing for postpartum FMH, as the cost-benefit of such testing in Rh mothers at risk has not been determined. (III-C) 4. Anti-D Ig 300 microg should be given routinely to all Rh-negative nonsensitized women at 28 weeks' gestation when fetal blood type is unknown or known to be Rh-positive. Alternatively, 2 doses of 100-120 microg may be given (120 microg being the lowest currently available dose in Canada): one at 28 weeks and one at 34 weeks. (I-A) 5. All pregnant women (D-negative or D-positive) should be typed and screened for alloantibodies with an indirect antiglobulin test at the first prenatal visit and again at 28 weeks. (III-C) 6. When paternity is certain, Rh testing of the baby's father may be offered to all Rh-negative pregnant women to eliminate unnecessary blood product administration. (III-C) 7. A woman with "weak D" (also known as Du-positive) should not receive anti-D. (III-D) 8. A repeat antepartum dose of Rh immune globulin is generally not required at 40 weeks, provided that the antepartum injection was given no earlier than 28 weeks' gestation. (III-C) 9. After miscarriage or threatened abortion or induced abortion during the first 12 weeks of gestation, nonsensitized D-negative women should be given a minimum anti-D of 120 microg. After 12 weeks' gestation, they should be given 300 microg. (II-3B) 10. At abortion, blood type and antibody screen should be done unless results of blood type and antibody screen during the pregnancy are available, in which case antibody screening need not be repeated. (III-B) 11. Anti-D should be given to nonsensitized D-negative women following ectopic pregnancy. A minimum of 120 microg should be given before 12 weeks' gestation and 300 microg after 12 weeks' gestation. (III-B) 12. Anti-D should be given to nonsensitized D-negative women following molar pregnancy because of the possibility of partial mole. Anti-D may be withheld if the diagnosis of complete mole is certain. (III-B) 13. At amniocentesis, anti-D 300 microg should be given to nonsensitized D-negativeesis, anti-D 300 microg should be given to nonsensitized D-negative women. (II-3B) 14. Anti-D should be given to nonsensitized D-negative women following chorionic villous sampling, at a minimum dose of 120 microg during the first 12 weeks' gestation, and at a dose of 300 microg after 12 weeks' gestation. (II-B) 15. Following cordocentesis, anti-D Ig 300 microg should be given to nonsensitized D-negative women. (II-3B) 16. Quantitative testing for FMH may be considered following events potentially associated with placental trauma and disruption of the fetomaternal interface (e.g., placental abruption, blunt trauma to the abdomen, cordocentesis, placenta previa with bleeding). There is a substantial risk of FMH over 30 mL with such events, especially with blunt trauma to the abdomen. (III-B) 17. Anti-D 120 microg or 300 microg is recommended in association with testing to quantitate FMH following conditions potentially associated with placental trauma and disruption of the fetomaternal interface (e.g., placental abruption, external cephalic version, blunt trauma to the abdomen, placenta previa with bleeding). If FMH is in excess of the amount covered by the dose given (6 mL or 15 mL fetal RBC), 10 microg additional anti-D should be given for every additional 0.5 mL fetal red blood cells. There is a risk of excess FMH, especially when there has been blunt trauma to the abdomen. (III-B) 18. Verbal or written informed consent must be obtained prior to administration of the blood product Rh immune globulin. (III-C) VALIDATION: These guidelines have been reviewed by the Maternal-Fetal Medicine Committee and the Genetics Committee, with input from the Rh Program of Nova Scotia. Final approval has been given by the Executive and Council of the Society of Obstetricians and Gynaecologists of Canada.

RhD isoimmunization and current management modalities

OBJECTIVE

To review the literature on current perspectives and treatment of RhD isoimmunization.

DATA SOURCES

A search was conducted on MEDLINE and CINAHL, and supplemental articles/ bulletins were obtained from cited references and the Web site of the American College of Obstetricians and Gynecologists. Recent texts also were reviewed. Key search words: isoimmunization, Rho (d) immune globulin, fetal erythroblastosis, intrauterine blood transfusions, alloimmunization.

STUDY SELECTION

Articles and comprehensive works from indexed journals in the English language relevant to key words and published after 1995 were evaluated. Historically relevant periodicals and texts were also reviewed and selected.

DATA EXTRACTION

Data were extracted and organized under the following headings: testing of the antepartum patient, antepartum treatment of isoimmunization, testing of the postpartum patient, anti-D immune globulin, antepartum anti-D immune globulin prophylaxis, other antepartum and obstetric indications for anti-D immune globulin administration, postpartum anti-D immune globulin prophylaxis, nursing implications, and future possibilities.

DATA SYNTHESIS

RhD isoimmunized pregnancies continue to contribute to worldwide perinatal and neonatal morbidity and mortality. This review describes the basic knowledge necessary to care for these pregnancies and the current management modalities.

CONCLUSIONS

The management options for RhD compromised gestations continue to evolve almost as quickly as technological advances are made. Multiple areas of research in this field have surfaced, and nurses can become valuable members of these research teams. The literature also indicates that with the available knowledge and resources, the current rate of RhD isoimmunization can be further decreased with closer adherence to proposed management guidelines by all health care professionals.

The incidence of significant fetomaternal hemorrhage in patients undergoing cesarean section

To determine the incidence of fetomaternal hemorrhage in patients undergoing cesarean section, Kleihauer-Betke tests were performed in the immediate postoperative period on 199 parturients. Some degree of hemorrhage was detected in 18.5% of patients, with 2.5% demonstrating greater than 30 ml of fetal blood. Comparison of groups on the basis of indication for cesarean delivery revealed no difference in rates of fetal hemorrhage. Because patients with greater than 30 ml of fetal blood would not be adequately protected from Rh sensitization by the standard 300 micrograms dose of Rh immune globulin, we recommend screening all Rh-negative patients undergoing cesarean section for the presence of significant fetomaternal hemorrhage.

Clinical use of the Kleihauer-Betke test

Results of all Kleihauer-Betke (KB) tests performed in 1988, at a center with 4,201 deliveries, were reviewed. Two hundred and twenty-seven tests were performed on maternal specimens from 205 patients. Eighteen (8.8%) of the 205 patients had positive test results. Medical records were available for 147 (71.7%) of the patients, including 17 of the 18 patients with a positive result. Indications for testing were: vaginal bleeding (33%), maternal trauma (31%), unexplained fetal death (5%), Rh incompatibility (3%), fetal distress (3%), and miscellaneous (24%). Most of the tests were performed antepartum. In only one case, and without clear benefit, did the KB test prompt a clinical intervention. At least two of the 18 patients with positive test results had probable false positive results due to maternal hemoglobin F. Such false positive KB test results may be misleading. Further evaluation of the role of the KB test in obstetrical management is needed.