Evaluating automated titre score as an alternative to continuous flow analysis for the prediction of passive anti-D in pregnancy.

OBJECTIVES: To evaluate the potential of the automated titre score (TS) as an alternative method to continuous flow analysis (CFA) for the prediction of the nature of anti-D in pregnancy. BACKGROUND: The 2016 revised British Society for Haematology (BSH) antenatal guidelines recommended a measurement of anti-D concentration by CFA to ensure the detection of potential immune anti-D. Due to high referral costs and resource pressures, uptake has been challenging for hospital laboratories. Serious Hazards of transfusion (SHOT) data have previously shown that this has contributed to missed antenatal follow ups for women with immune anti-D and neonates affected by haemolytic disease of the fetus/newborn. METHODS/MATERIALS: In this multicentre comparative study, samples referred for CFA quantification were also tested by an ORTHO VISION automated anti-D indirect antiglobulin test (IAT) serial dilution and then converted to TS. CFA results and history of anti-D prophylaxis were used to categorise samples as passive or immune, with the aim of determining a potential TS cut-off for CFA referral of at risk patients. RESULTS: Five UK National Health Service (NHS) trusts generated a total of 196 anti-D TS results, of which 128 were classified as passive and 68 as immune. Diagnostic testing of CFA and TS values indicated a TS cut-off of 35 to assist in distinguishing the nature of anti-D. Using this cut-off, 175 (89%) results were correctly assigned into the passive or immune range, giving a specificity of 92.19% and a negative predictive value of 91.47%. CONCLUSION: TS in conjunction with clinical and anti-D prophylaxis history can be used as a viable and cost-effective alternative to CFA in a hospital laboratory setting.

The Kidd (JK) Blood Group System.

The Kidd blood group system was discovered in 1951 and is composed of 2 antithetical antigens, Jka and Jkb, along with a third high-incidence antigen, Jk3. The Jk3 antigen is expressed in all individuals except those with the rare Kidd-null phenotype. Four Kidd phenotypes are therefore possible: Jk(a+b-), Jk(a-b+), Jk(a+b+), and Jk(a-b-). The glycoprotein carrying the Kidd antigens is a 43-kDa, 389-amino acid protein with 10 membrane-spanning domains which functions as a urea transporter on endothelial cells of the renal vasa recta as well as erythrocytes. The HUT11/UT-B/JK (SLC14A1) gene encoding this glycoprotein is located on chromosome 18q12-q21. The Jka and Jkb antigens are the result of a single-nucleotide polymorphism present at nucleotide 838 resulting in an aspartate or asparagine amino acid at position 280, respectively. The Kidd blood group can create several difficult transfusion situations. Besides the typical acute hemolytic transfusion reactions common to all clinically relevant blood group antigens, the Kidd antigens are notorious for causing delayed hemolytic transfusion reactions due to the strong anamnestic response exhibited by antibodies directed against Kidd antigens. The Kidd-null phenotype is extremely rare in most ethnic groups, but is clinically significant due to the ability of those with the Kidd-null phenotype to produce antibodies directed against the high-incidence Jk3 antigen. Anti-Jk3 antibodies behave in concordance with anti-Jka or anti-Jkb possessing the capability to cause both acute and delayed hemolytic reactions. Antibodies against any of the 3 Kidd antigens can also be a cause of hemolytic disease of the fetus and newborn, although this is generally mild. In this review, we will outline the makeup of the Kidd system from its historical discovery to the details of the Kidd gene and glycoprotein, and then discuss the practical aspects of Kidd antibodies and transfusion reactions with an extended focus on the Kidd-null phenotype. We will end with a brief discussion of the donor aspects related to the screening and supply management of blood from donors with the rare Jk(a-b-) phenotype.

Feto-maternal haemorrhage assessment in a woman with a large population of red blood cells containing fetal haemoglobin.

BACKGROUND: FMH quantification is necessary to calculate an individual dose of prophylactic anti-RhD immunoglobulin and to diagnose fetal anaemia causes. We encountered a healthy woman with a numerous RBCs containing fetal haemoglobin (HbF). AIMS: To investigate the cause of this sign and the correct evaluation of fetal RBCs in maternal circulation. MATERIALS AND METHODS: Patients samples and artificial mixtures were tested by microscopic Kleihaur-Betke (KB) and flow cytometric (FC) tests with anti-HbF + anti-CA (carbonic anhydrase), and with anti-D. The patient's blood count with reticulocyte parameters, and concentration of bilirubin, haptoglobin, iron, transferrin, ferritin, hepcidin, sTR, HbF, HbA2 were measured. Genes coding the beta- and gamma-globin were sequenced. RESULTS: It was impossible to distinguish the population of fetal and maternal HbF positive cells using KBT and FC with anti-HbF. Application of anti-CA and anti-D allowed to separate them. Maternal blood haematological and biochemical parameters were normal but HbF was 3.3% of total Hb concentration (normal < 1%). There were no mutations in the beta- and gamma-globin genes, but Xmn I polymorphism at -158 position in gamma-globin gene was detected in the homozygous state. CONCLUSION: A very large population of HbF positive cells sometimes can be detect in a healthy woman. Implementation of the various procedures for FMH assessment is necessary in the such case, otherwise, the detection of fetal erythrocytes may not be possible or can give false results.

Sickle cell disease in areas of immigration of high-risk populations: a low cost and reproducible method of screening in northern Italy.

BACKGROUND: From 2005 to 2010, we observed a 10-fold increase of newly diagnosed sickle cell disease in children in the province of Modena (northern Italy). The median age at diagnosis was 24 months. Since these children are too old for optimal disease management, earlier detection of the disease is needed for prophylaxis and comprehensive care before the occurrence of clinical manifestations. MATERIALS AND METHODS: In each Maternity Unit of the province of Modena, blood samples are collected daily for assessment of haemolytic disease of the newborn. We designed a selective, low-cost haemoglobin screening for sickle cell disease in high-risk immigrants. We enrolled 469 mothers from sub-Saharan countries and their neonates for a primary screening of peripheral blood haemoglobin variants using high-performance liquid chromatography. RESULTS: Of the 469 women approached, 330 (70.36%) agreed to undergo the test. Ninety-two (27.88%) were carriers of variant haemoglobin, 48 newborns (51%) of these carriers had the carrier trait and 9 (9.6%) were affected (haemoglobin SC compound heterozigote - HbSC, haemoglobin S homozygote - HbSS). DISCUSSION: These results support the feasibility and usefulness of a selective screening for the detection of haemoglobin variants in high-risk subjects in an area in which sickle cells disease is not endogenous. We achieved the goal of detecting subjects with carrier trait/disease in order to implement preventive measures that reduce the clinical manifestations of sickle cell disease. We are, however, aware that it will be necessary to extend this screening to the overall population in the near future.

Wasted health care dollars. Routine cord blood type and Coombs' testing.

OBJECTIVE: To determine if selective newborn cord blood testing (NCBT) could contain costs without increasing morbidity of hemolytic disease of the newborn (HDN). DESIGN: A national telephone survey confirmed the common practice of routine blood type and Coombs' NCBT. Two 12-month study arms, retrospective and prospective, were conducted. Hemolytic disease of the newborn was studied retrospectively under an unrestricted NCBT policy. Then, HDN was studied after a policy change that restricted NCBT to patients in newborn intensive care units and normal newborns with clinical jaundice or Rh-negative mothers, and/or positive maternal antibody screenings, or unavailable maternal blood testing. PARTICIPANTS: All newborns (N = 8501) at the Metro-Health Medical Center, Cleveland, Ohio, were studied (retrospective arm, all 1989 admissions; prospective arm, all July 1990 to June 1991 admissions). OUTCOME MEASURES: Blood type and Coombs' NCBT, maternal blood type and antibody screening, Hobel risk scores for clinical severity of newborn hospitalization, duration of hospitalizations, and peak serum bilirubin levels. RESULTS: No quantitative or qualitative increases in morbidity from jaundice were detected by retrospective analysis with unrestricted NCBT, or prospectively after selective testing on 4498 newborns. Each study arm resulted in 15 readmissions for jaundice; these included two patients with ABO HDN. Furthermore, selective testing resulted in performance of NCBTs on only 390 infants in the "normal" nursery (24% of the original sample). Estimates projected on 1991 US births (4,111,000) showed that selective NCBT offers potential yearly savings above $30.8 million of patient charges, savings above $11.3 million of hospital costs, and the reassignment of more than 112 personnel full-time equivalents. CONCLUSION: Selective NCBT decreases the use of resources and costs without apparent additional patient morbidity from HDN.

[Clinical aspects of prenatal prevention of rhesus incompatibility]. / Klinische Aspekte der antenatalen Rhesus-Prophylaxe.

The postnatal treatment with anti-D immunoglobulin to prevent rhesus sensitization is successful in about 90% of all rhesus-negative mothers at risk. Failures derive mostly from large fetomaternal hemorrhages during the last months of pregnancy. Studies from Canada, Great Britain and Sweden have shown that the injection of an additional dosage of anti-D during the 28th to 34th week of pregnancy results in a further 90% reduction of the failure rate. Although there is only a limited number of cases of hemolytic diseases in the newborn, the cost-effect ratio of this prophylactic treatment calculated for the Federal Republic of Germany shows not only a medical but also an economic benefit.

Assessment of size of small volume feto-maternal bleeds. A new method of quantification of the Kleihauer technique.

The risk of Rh-isoimmunization is probably related to the volume of foeto-maternal bleeding. With the Kleihauer technique foetal cells may be detected in maternal blood, but estimation of the size of foetal bleed the cells represent is at present difficult and open to serious error.A new method of quantifying the technique by using a standard volume of maternal blood, and a simple machine for the preparation of comparable blood films, is described. The new method eliminates many of the errors of previous techniques, and should be capable of automation for large-scale screening programmes.