Addendum for guidelines for blood grouping and red cell antibody testing during pregnancy. BCSH Transfusion Task Force

Comparative evaluation of DTT treated ABO isoagglutinin titres performed by two methods with solid phase red cell adhesion (SPRCA) titres

BACKGROUND AND AIMS

Measurement of actual concentration of IgG requires methods like treatment of serum with dithiothreitol (DTT). This study was aimed at comparing of DTT treated ABO titres performed by conventional test tube technique (CTT) and column agglutination technique (CAT) with HA/SPRCA.

MATERIALS AND METHODS

This was a prospective, observational study conducted from October 2019 to March 2020. All consecutive A, B and O group donors who gave consent for participation were included. All samples were tested by CTT and CAT before and after DTT treatment (pCTT, pCAT) and with HA/SPRCA.

RESULTS

A total of 300 donors were included; 100 each from A, B and O blood group donors. Group O titres were higher than group A/B titres. Group O titres were highest when performed by pCAT, followed by pCTT and lowest by HA/SPRCA. Group A/B titres were highest when performed by HA/SPRCA, followed by pCAT and pCTT for anti-A and highest when performed by pCAT, followed by HA/SPRCA and lowest by pCTT for anti-B.

CONCLUSION

Results obtained by pCAT were closer to results obtained by pCTT, whereas those obtained by HA/SPRCA were variable. SPRCA offers the advantage of automation, no inter-observer variation and less time consumption because IgM interference is not observed with SPRCA, thus providing an alternative to pCTT. However, these methods cannot be used interchangeably and to discern the most suitable method, a clinical impact of these results needs to be studied.

National comparative audit of blood transfusion: 2014 audit of transfusion services and practice in children and adults with sickle cell disease

OBJECTIVES

To determine the organisational resources in place; what blood was being transfused, why, how, where, when and by whom; whether laboratory support and policies met standards for patients with sickle cell disease (SCD).

BACKGROUND

SCD affects 14 000 people in the United Kingdom (UK). Standards and guidelines do not cover all aspects of transfusion in SCD and there are no data on their use; people may become very sick without warning presenting to non-specialist hospitals; blood services are increasingly supplying units for transfusion in SCD with little data on their use.

METHODS

A retrospective audit of transfusion services/practice for people with SCD who had received a transfusion in January-July 2014 in participating hospitals in the UK and Republic of Ireland (ROI).

RESULTS

Eighty-four hospitals submitted 1290 cases, 75% of cases came from 18 hospitals submitting 25 or more cases. Transfusions (91.2% [1164/1276]) were administered to patients with HbSS, 60% (732/1227) of patients needed Rh CE negative blood. Transfusion episodes (4528) were recorded, of which 84% were elective. Stroke prevention accounted for 42% of all transfusions; adults received 56% of transfusions of which 50% were automated red cell exchange (RCE), children received 44% of transfusions of which 87% were simple transfusions.

CONCLUSIONS

There was a paucity of appropriate clinical management protocols, adequately trained staff and network arrangements. The high numbers of children being transfused, disparity in transfusion modality between children and adults and the high frequency of the CE negative Rh phenotype were noted.

Prevalence and obstetric outcome of women with red cell antibodies in pregnancy at the Leeds Teaching Hospitals NHS Trust, West Yorkshire, England

OBJECTIVE

The prevalence of red cell antibodies in pregnancy varies with ethnicity and geographical location, while the obstetric outcome depends on the available standard of care. Despite being the tertiary fetal medicine centre in West Yorkshire, the prevalence of red cell antibodies, and the outcome of pregnancies associated with these antibodies at the Leeds University Teaching Hospitals Trust remains unreported. This article aims to provide this information for the purpose of patient education and counselling.

STUDY DESIGN

The data of pregnant women with red cell antibodies between January 2011 and December 2016 was obtained from the Trust's database and reconciled with the Fetal Medicine Unit records using Viewpoint©. Fetal anaemia requiring in utero transfusion (IUT) was defined as a Middle Cerebral Artery Peak Systolic Velocities ≥ 1.5multiple of the median expected for gestational age. The mean gestational age at delivery, and perinatal outcomes of the pregnancies were recorded.

RESULT

Overall, 398 of the 96, 692 pregnant women that were screened had red cell antibodies, giving a prevalence of 1: 242 pregnancies. The Anti- E and Anti-M antibodies were the most common (114 women; 28.6%, and 112 women; 28.1% respectively), but did not cause fetal anaemia in isolation, while anti-D alloimmunization was the predominant indication for in-utero transfusion (IUT). Anti-DE and anti-Kell antibodies had the highest mean number of transfusions per pregnancy. The mean gestational age at delivery was 34 ± 2weeks. Post-transfusion fetal demise was recorded in two hydropic fetuses, both at a gestational age of 25 weeks; giving a transfusion-related mortality rate of 2.5%.

CONCLUSION

The prevalence of red cell antibodies at West Yorkshire is lower compared with reports from other Caucasian populations.Nevertheless, these antibodies are important causes of iatrogenic preterm delivery and fetal morbidity. The prognosis is however good with prompt diagnosis and management.

Production of soluble recombinant proteins with Kell, Duffy and Lutheran blood group antigen activity, and their use in screening human sera for Kell, Duffy and Lutheran antibodies

The aim of this study was to show that soluble recombinant (sr) proteins can mimic blood group antigens and be used to screen human sera for blood-group-specific antibodies. The blood of all pregnant women and pretransfusion patients should be screened for blood-group-specific antibodies to identify and monitor pregnancies at risk of haemolytic disease of the foetus and newborn (HDFN), and to prevent haemolytic transfusion reactions. Current antibody screening and identification methods use human red blood cell panels, which can complicate antibody identification if more than one antibody specificity is present. COS-7 cells were transfected to produce sr forms of the extracellular domains of the red blood cell membrane proteins that express Kell, Duffy or Lutheran blood group antigens. These sr proteins were used to screen for and identify anti-Kell, anti-Duffy or anti-Lutheran blood-group-specific allo-antibodies in human sera by haemagglutination inhibition and in solid-phase enzyme-linked immunosorbent assays (ELISAs). There is a positive correlation (correlation coefficient 0.605, P value 0.002) between antibody titre by standard indirect antiglobulin test (IAT) and signal intensity in the ELISA test. This work shows that sr proteins can mimic blood group antigens and react with human allogeneic antibodies, and that such proteins could be used to develop solid-phase, high-throughput blood group antibody screening and identification platforms.

RhD haemolytic disease of the fetus and the newborn

When an RhD negative mother is exposed to the RhD positive red cells (usually as transplacental haemorrhage), she develops allo-anti-D which crosses the placenta and then results in the destruction of fetal red cells. Clinical manifestations of RhD haemolytic disease (HDN) range from asymptomatic mild anaemia to hydrops fetalis or stillbirth associated with severe anaemia and jaundice. HDN was a significant cause of fetal mortality and morbidity until the introduction of amniocentesis, intrauterine transfusion, controlled early delivery and exchange transfusion in the management of severely alloimmunised women and their fetuses. The objective of monitoring alloimmunised women is to identify fetal anaemia and prevent the development of life-threatening hydrops. Evaluation involves assessing the history of previous pregnancies; serial estimation of maternal anti-D levels; serial ultrasound measurements; serial amniocentesis; fetal blood sampling, and intrauterine transfusion when indicated. Diagnostic genotyping by DNA-based methods can identify at-risk RhD positive fetuses early in gestation. Identification of transplacental haemorrhage (TPH) as the stimulus for anti-D antibody production led to the development of anti-D immunoglobulin prophylaxis for at-risk RhD negative women who are not already alloimmunised. Prevention includes administration of anti-D immunoglobulin for any event associated with TPH during pregnancy, and at delivery of an RhD positive infant. Prophylactic routine administration of anti-D immunoglobulin at 28 (and 34) weeks gestation, in addition to the above, has reduced alloimmunisation to <1% of RhD negative women carrying an RhD positive fetus.