Dose Of Rh Immune Globulin Research Articles

Rh immune globulin immunoprophylaxis after RhD-positive red cell exposure in RhD-negative patients via transfusion: A survey of practices.

Current Association for the Advancement of Blood & Biotherapies (AABB) standards require transfusion services to have a policy on Rh immune globulin (RhIG) immunoprophylaxis for when RhD-negative patients are exposed to RhD-positive red cells. This is a survey of AABB-accredited transfusion services in the United States (US) regarding institutional policies and practices on RhIG immunoprophylaxis after RhD-negative patients receive RhD-positive (i.e., RhD-incompatible) packed red blood cell (pRBC) and platelet transfusions. Approximately half of the respondents (50.4%, 116/230) have policies on RhIG administration after RhD-incompatible pRBC and platelet transfusions, while others had policies for only pRBC (13.5%, 31/230) or only platelet (17.8%, 41/230) transfusions, but not both. In contrast, 18.3% (42/230) report that their institution has no written policies on RhIG immunoprophylaxis after RhD-incompatible transfusions. Most institutions (70.2%, 99/141) do not have policies addressing safety parameters to mitigate the risk of hemolysis associated with the high dose of RhIG required to prevent RhD alloimmunization after RhD-incompatible pRBC transfusions. With approximately half of US AABB-accredited institutions report having policies on RhIG immunoprophylaxis after both RhD-incompatible pRBC and platelet transfusions, some institutions may not be in compliance with AABB standards. Further, most with policies on RhIG immunoprophylaxis after RhD-incompatible pRBC transfusion do not have written safeguards to mitigate the risk of hemolysis associated with the high dose of RhIG required. This survey underscores the diverse and inadequate institutional policies on RhIG immunoprophylaxis after RhD exposure in Rh-negative patients via transfusion. This observation identifies an opportunity to improve transfusion safety.

Use of Fetal Hemoglobin Quantitation for Rh-Positive Pregnant Females: A National Survey and Review of the Literature.

The Kleihauer-Betke (KB) test is validated for estimating the dose of Rh immune globulin needed for Rh-negative pregnant females. However, some clinicians are also ordering the test for Rh-positive women. The degree to which this practice occurs is unknown. To evaluate the number of laboratories that perform the KB test on Rh-positive pregnant women, and to establish current ordering practices for this indication. We added 9 supplemental questions regarding KB test use for fetomaternal hemorrhage to the 2016 College of American Pathologists proficiency test survey. We also reviewed the available literature regarding the diagnostic utility of the KB test for Rh-positive women. A total of 1578 surveys were evaluated and revealed that 52% (824) of respondents perform these tests for Rh-positive women, and more than 50% (440 of 819; 53.7%) of these laboratories report that the results for Rh-positive women are treated as important or very important. The KB test is commonly used for Rh-positive women, and the information obtained from the test is considered as urgent and important. However, the available literature in support of this practice is still nonconclusive.

A Guide to Terminology for Rh Immunoprophylaxis

Rh immunoprophylaxis for Rh-negative women requires an understanding of terminology used for Rh blood typing laboratory reports. The pathophysiology of Rh hemolytic disease of the fetus and newborn was elucidated by studies in rhesus monkeys. Subsequent studies revealed that the human blood group antigen responsible for Rh hemolytic disease of the newborn (D antigen) is related to, but different from, the rhesus monkey antigen. Weak expression of the D antigen on red cells, originally termed D, is currently reported by laboratories as a "serologic weak D phenotype," which can be further defined by RHD genotyping to be either a weak D type or a partial D phenotype. Weak D types 1, 2, or 3 are molecularly defined RHD weak D types, which have an adequate number of intact D antigens to be managed safely as Rh-positive. Partial D phenotypes result from mutations causing loss of one or more D epitopes. Most persons with a partial D phenotype have sufficient D antigen to type as Rh-positive. Some women with a partial D phenotype are detected as serologic weak D phenotypes by routine Rh typing. Whether they type as Rh-positive or serologic weak D phenotype, after being exposed to Rh-positive red cells by transfusion or pregnancy, women with partial D phenotype can form anti-D antibodies and, if they do, are at risk for hemolytic disease of the fetus and newborn. A pregnant woman with a laboratory report of a serologic weak D phenotype should be further tested for her RHD genotype to resolve whether her case should be managed as Rh-positive or Rh-negative. For more than five decades, the practice of Rh immunoprophylaxis has remained unchanged in terms of the dose of Rh immune globulin and timing of injections. In contrast, advances in the science of Rh blood typing have resulted in a continuously evolving terminology, obliging obstetricians to update their vocabulary to guide their practice. The following review and glossary provide guidance for current Rh terminology and the rationale for changes.

Obstetrics and gynecology physician knowledge of Rh immune globulin prophylaxis.

Previous studies have shown that more than 20% of laboratories would have recommended inaccurate doses of Rh immune globulin (RhIG) in hypothetical cases. Efforts have been made in educating laboratories in correct dosing calculations; however, obstetricians are most often responsible for ordering RhIG. The objective of this study was to assess knowledge of RhIG indications and dosing among obstetrics and gynecology (OB/GYN) physicians in the United States. An anonymous 17- question online survey was distributed to all OB/GYN resident and attending physicians affiliated with US residency training programs. A total of 165 surveys were collected, with 139 fully completed. Ninety-two percent of respondents correctly recognized the need for RhIG in D- patients with negative antibody screens. In a scenario of a fetomaternal hemorrhage (FMH) of 45 mL, only 22% of respondents correctly chose the appropriate RhIG dosage. Of those who were correct, 10% had correctly identified 30 mL as the amount of fetal whole blood covered by one dose of RhIG, while 48% incorrectly identified 15 mL (n=31). A total of 49.3% of respondents reported residency as the most recent formal training on RhIG dosing and 35% reported never (n=140). Our study found that OB/GYN physicians are knowledgeable regarding indications for RhIG immunoprophylaxis but were insufficient at calculating dosages in cases of FMH. More standardized education and training among OB/GYN physicians may decrease the risk of maternal alloimmunization, in part because RhIG dosage recommendations from laboratories are not standard practice.

It's time to phase in RHD genotyping for patients with a serologic weak D phenotype. College of American Pathologists Transfusion Medicine Resource Committee Work Group.

It's time to phase in RHD genotyping for patients with a serologic weak D phenotype. College of American Pathologists Transfusion Medicine Resource Committee Work Group.

Postpartum Rh Immunoprophylaxis

The postpartum dose of Rh immune globulin varies according to an individual laboratory estimation of fetal red blood cells in each mother's peripheral blood. In the United States, a four-step procedure determines the postpartum dose (number of vials of 300 micrograms; 1,500 international units) of Rh immune globulin (anti-D) for each RhD-negative mother who has delivered an RhD-positive newborn and has not already formed anti-D. The first step is a rosette fetal red blood cell screen to determine whether an excessive (greater than 30 mL fetal whole blood) fetomaternal hemorrhage occurred. If the rosette screen is negative, the mother receives one vial of Rh immune globulin for Rh immunoprophylaxis. If the rosette screen is positive, the blood sample is retested by a quantitative method, typically an acid-elution (Kleihauer-Betke) assay. The result of the acid-elution assay is converted to an estimation of the volume of the fetomaternal hemorrhage, which is the basis for calculating the dose of Rh immune globulin. The acid-elution assay is subjective, imprecise, and poorly reproducible. As a result, the formula for calculating the dose includes a precautionary adjustment, adding an extra vial in borderline situations to prevent underdosing. Flow cytometry is a more precise method for quantifying a fetomaternal hemorrhage. However, few hospitals use flow cytometry, because it is not cost-effective to maintain an expensive, high-technology laboratory service for the relatively few occasions when a precise quantitative determination of fetomaternal hemorrhage is required.

Clinically Silent Massive Fetomaternal Hemorrhage: Important Lessons from an Illustrative Case

Massive fetomaternal hemorrhage (FMH) >150 mL is rare and may occur in the absence of high-risk obstetrical events. The significance of FMH in Rh D-negative women is alloimmunization with an increased risk of hemolytic disease of the newborn in subsequent Rh D-positive pregnancies and adverse outcomes for the fetus/neonate. The Kleihauer-Betke (KB) acid elution test is used to quantify fetal erythrocytes in the circulation of Rh D-negative women postpartum and to calculate the dose of Rh immune globulin (RhIG) needed for prophylaxis against alloimmunization. In this case, the KB stain unexpectedly revealed 4.5% fetal cells, a finding consistent with a massive FMH of 225 mL, in the absence of a predisposing cause and clinical signs in the infant. This case underscores the importance of FMH quantification in all Rh D-negative women with Rh D-positive fetuses, uncomplicated pregnancies, and healthy newborns. We discuss factors that can affect KB test performance and caveats in interpretation.

Laboratory methods for Rh immunoprophylaxis: a review

Abstract The recommended dose of Rh immune globulin for postpartum Rh immunoprophylaxis is based on an estimation of the volume of the fetomaternal hemorrhage, if any, measured as the percent of fetal RBCs in a sample of the D– mother’s blood. Laboratory methods for distinguishing fetal from maternal RBCs have been based on their different blood types (D+ versus D–) or predominant hemoglobin content (hemoglobin F versus hemoglobin A). We conducted a review of the medical literature describing laboratory methods for detecting and quantifying fetal RBCs in maternal blood samples. We also used data collected for the College of American Pathologists Fetal RBC Detection Surveys to determine which laboratory methods are used currently in hospitals in the United States. The rosette screen is used widely for identifying D– mothers who may require additional doses of Rh immune globulin for postpartum immunoprophylaxis. As the rosette screen targets the D antigen, it is not suitable for detecting a fetomaternal hemorrhage in D+ mothers or when the D type of the fetus or newborn is D– or unknown. The acid-elution (Kleihauer-Betke) assay is a sensitive laboratory method for quantifying a fetomaternal hemorrhage, but it is tedious, often inaccurate, and difficult to reproduce. Flow cytometry, using anti-D or anti-hemoglobin F reagents, offers a more precise quantification of fetal RBCs in maternal blood. However, flow cytometry services for this function are available in relatively few hospital laboratories in the United States because of logistic and fiscal impediments. Immunohematology 2010;26:92–103.

Inaccurate Doses of Rh Immune Globulin After Rh-Incompatible Fetomaternal Hemorrhage—Survey of Laboratory Practice

Inaccurate Doses of Rh Immune Globulin After Rh-Incompatible Fetomaternal Hemorrhage—Survey of Laboratory Practice

Inaccurate Doses of Rh Immune Globulin After Rh-Incompatible Fetomaternal Hemorrhage: Survey of Laboratory Practice

Abstract 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 ...

Inaccurate Doses of Rh Immune Globulin After Rh-Incompatible Fetomaternal Hemorrhage: Survey of Laboratory Practice

Abstract 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 μg/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.

Detection of multiple passively acquired alloantibodies following infusions of IV Rh immune globulin.

Passively acquired blood group alloantibodies are detected regularly after infusions of IV Rh immune globulin (RhIG) for the treatment of immune thrombocytopenic purpura (ITP) in D+ patients. Blood samples from 16 D+ patients with ITP were tested after treatment with IV RhIG for the presence of passively acquired alloantibodies. Similar studies were conducted for three D- patients after injections of IM RhIG for Rh immunoprophyl-axis. Four production lots of IV RhIG and 2 lots of IM RhIG were tested for the presence of alloantibodies. All 16 D+ patients with ITP developed a positive DAT, as well as positive antibody detection test results, after infusions of IV RhIG. All postinfusion plasma samples contained anti-D, as well as one or more additional antibodies, usually anti-C, -E, -G, -V, or -Fy(a). Eluates from patients' RBCs with positive DAT results contained multiple passively acquired alloantibodies. Multiple alloantibodies were detected in samples of different production lots of IV RhIG or IM RhIG. No acute transfusion reactions were observed in five D+ patients with ITP who had been treated with IV RhIG and had been given serologically incompatible D+ RBCs. After injections of IM RhIG, the only passively acquired alloantibody detected was anti-D. Plasma samples from D+ patients with ITP treated with IV RhIG regularly contained anti-D and multiple other passively acquired Rh, Duffy, or Kidd system alloantibodies. Postinfusion RBC samples all had positive DAT results with eluates containing anti-D and multiple other Rh, Duffy, or Kidd system antibodies. The consistent detection of multiple passively acquired alloantibodies after IV RhIG, in contrast to the detection of anti-D only after IM RhIG, reflects the immediate effect of the entire (bolus) dose of RhIG by the IV route, the dose for treating ITP that is approximately 10 times the dose for Rh immunoprophylaxis, and the expected serologic incompatibility with recipients' D+ RBCs.

A gel technology system to determine postpartum RhIG dosage

Abstract Failures of Rh immune globulin (RhIG) prophylaxis occur when the dose is too small. We report a test using a gel technology (GT) method to replace the Kleihauer–Betke (K–B) test to assess fetomaternal hemorrhage (FMH) and assist in determining the minimum necessary dose of RhIG. Cord blood (O, D+) was mixed with adult blood (O D–) to mimic an FMH of 10 mL, 20 mL, 28 mL, and 40 mL. Test samples were incubated with anti-D at known concentrations and centrifuged. The supernatant was titrated against D+ and D– red cells using GT and an interpretation of the required RhIG dose was made. Results were compared with the K–B test. Results were easily discernible and interpretations leading to determination of recommended RhIG dosage were reproducible. Correlation to standard K–B testing was confirmed. Elapsed time for result availability by GT testing was 60 minutes, with a direct technical time requirement of 30 minutes. The GT system is easier, objective, and quantitative, and compares well to the standard K–B test. A single procedure will allow assessment of the extent of FMH in the great majority of cases. This technique works well in determining the appropriate dose of anti-D required to treat D– patients with D+ newborns. There are potential cost savings in decreased use of RhIG, less direct technical time required, and more rapid availability of results. Immunohematology 2000;16:115–119.

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 > 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 > 30 ml of fetal blood would not be adequately protected from Rh sensitization by the standard 300 µg dose of Rh immune globulin, we recommend screening all Rh-negative patients undergoing cesarean section for the presence of significant fetomaternal hemorrhage.

Rh immune globulin and the Rh-positive Du variant, mother.

Questions have been raised by statements of the American College of Obstetricians and Gynecologists that Rh immune globulin should be given to all Rh positive, Du variant, mothers who have recently delivered Rh positive infants. This practice is not recommended. However, blood banks must assure that a positive Du test on a mother's blood sample is not caused by a massive fetal-maternal hemorrhage. Failure to recognize this cause of a positive Du test may result in the administration of an inadequate dose of Rh immune globulin.

Additional Uses for Immune Globulin

Dr. Stiehm's review article in Pediatrics (63:301, 1979) is excellent in its comprehensive treatment of the use of immune serum globulin. However, the portion on Rh immune globulin (RhIG) has two omissions regarding current management of the Rh-negative woman: (1) Amniocentesis is an indication for considering the use of RhIG in the Rh-negative pregnant woman, and (2) evidence of massive fetal-maternal hemorrhage (placenta abruptio, placenta previa, or neonatal anemia) in the Rh-negative woman should be cause for an attempt to determine the magnitude of that bleed and gauge the dose of RhIG to the volume of that bleed.

Reduced Dose Of Rh Immunoglobulin Following First Trimester Pregnancy Termination

The efficacy and safety of a 50-microgram dose of Rh immune globulin for prevention of Rh isosensitization following first trimester vacuum abortion are evaluated in this study. A total of 1027 women undergoing abortion at three outpatient facilities participated in the study; 755 (73.5%) completed follow-up serologic screening 6 months after termination of pregnancy. None showed serologic evidence of Rh sensitization at the time of followup. No serious adverse reactions to the drug were observed.

The Risk of Immunization to IgG Following Rh Immune Globulin Therapy

Three hundred thirteen women were typed for Gm and Inv factors and screened for the presence of antibodies to gamma globulin both before receiving Rh immune globulin and at six weeks, three, six, and nine months after injection. Thirty‐five of the 313 women received multiple doses of Rh immune globulin following one or more pregnancies. In this group of patients, the incidence of anti‐gamma globulins was no greater than in the women given a single 0.7 to 2.25 ml dose. Anti‐gamma globulins were found in only 17 women (5.4%). Eleven had antibody prior to treatment and in six it first appeared in post injection specimens. Five of the women had allotype specific Gm agglutinators. In three, these were found in the pretreatment specimens. No evidence of Rh sensitization was demonstrable in the eleven Rh immune globulin recipients who had circulating anti‐gamma globulins at the time of treatment. Our data indicates that the risk of sensitization to Gm and Inv factors is a function of the concentration of the antigen in the Rh immune globulin and the pheno‐type of the recipients.

Fetal cell counting as a guide to prevention of Rh sensitization.

Administration of a standard dose of Rh immune globulin in the immediate postpartum period is adequate to protect 93 per cent of the Rh negative mothers that would otherwise become sensitized. It is now possible by utilizing fetal cell counts to identify those patients in which the standard dose of immune globulin is inadequate for protection. A method for easy and accurate identification of potential failures is described.

Studies on Rh prophylaxis. II. Rh immune prophylaxis after transfusion with Rh-positive blood.

The incidence of Rh immunization of Rh‐negative volunteers given approximately 500 ml of Rh‐positive blood is 18 out of 22. Complete Rh immune suppression was achieved in a treated group given a precalculated dose of Rh immune globulin. Rh immune prophylaxis is safe, effective and practical after transfusion accidents or massive fetomaternal hemorrhages where large volumes of Rh‐positive blood enter the circulation of Rh‐negative individuals.The dose of RhoGAM,* Rho(D) Immune Globulin (Human) found to be effective in suppressing an immune response to the Rh factor was 20 μg/ml of red blood cells (not whole blood). Since each vial contains no less than 300 μg of anti‐Rho(D), the potency for RhoGAM is 15 ml of red blood cells/vial.