Red Cell Alloimmunization Research Articles

Fetal Anemia: Determinants and Perinatal Outcomes according to the Method of Intrauterine Blood Transfusion

Introduction: Fetal anemia from hemolytic disease treated by intrauterine transfusion (IUT) can be performed by intraperitoneal, intracardiac, and intravascular transfusion (IVT). Objective of our study was to compare different transfusion techniques. Methods: Retrospective review of IUT secondary to red cell alloimmunization was conducted at eight international centers from 2012 to 2020. Severe anemia suspected if middle cerebral artery peaks systolic velocity ≥1.5 multiples of the median. Demographic, delivery, and postnatal variables were analyzed. Results: Total of 344 procedures, 325 IVT and 19 other techniques (non-IVT) included. No difference in demographics, history of stillbirth (20.5 vs. 15.8%, p = 0.7), prior pregnancy IUT (25.6 vs. 31.6%, p = 0.5) or neonatal transfusion (36.1 vs. 43.8%, p = 0.5). At first IUT, non-IVT had higher hydrops (42.1% vs. 20.4%, p = 0.03), lower starting hematocrit (13.3% [±6] vs. 17.7% [±8.2], p = 0.04), and trend toward lower gestational age (24.6 [20.1–27] vs. 26.4 [23.2–29.6] weeks, p = 0.08). No difference in birthweight, neonatal phototherapy, exchange, or simple transfusion was observed. Conclusion: This is one of the largest studies comparing techniques to treat fetal anemia. IVT was most performed, other techniques were more likely performed in hydrops, and lower starting hematocrit was seen. Neither technique affected outcomes. This study may suggest that physician’s experience may be the strongest contributor of outcomes.

Frequency of Red Cell Alloimmunization in Patients with Thalassemia Major: A Report from the Southwest of Iran

Background: The mainstay of managing severe β-thalassemia remains lifelong blood transfusion. Mismatched red blood cell phenotypes between donors and recipients in multiple blood transfusions can result in the development of alloimmunization in recipients. The aim of this study was to determine the frequency of major and subgroup antigens and their phenotypes in thalassemia major patients.
 Materials and Methods: This cross-sectional descriptive study was performed on 105 patients with thalassemia major who referred to Baghaei Hospital in Ahvaz in 2021. Their alloimmunization to erythrocyte antigens was determined with standard tubular antibody search kits.
 Results: Among the thalassemia major patients participating in the study, 51 were female (48.45%). The mean age of the participants was 21.10 ± 5.8 years. Out of the 105 patients studied, 26 had detectable alloantibodies in the serum (24.7%). The two groups of patients with positive and negative alloantibodies were significantly different in terms of Rh and C blood groups (P-values of 0.03 and 0.05, respectively). There was no significant association between the existence alloantibody and age, gender, spleen condition and the time of first transfusion (P > 0.05).
 Conclusion: It was concluded that red blood cell matching, at least for Rh and C groups, is necessary to prevent alloimmunization in thalassemia major patients.

Effect of delayed cord clamping on red blood cell alloimmunization: a retrospective cohort study

Although delayed cord clamping has well-known benefits for preterm and term neonates, it has been inadequately assessed in alloimmunized neonates. This study aimed to evaluate the benefits and risks of delayed cord clamping in alloimmunized neonates. This was a retrospective comparative pre-post cohort study conducted from 2003 to 2018 in a tertiary care center in France. All living singleton neonates whose mothers were followed up for red blood cell alloimmunization during gestation and confirmed at birth (N=224) were included. Neonates were either exposed to immediate (n=125) or delayed cord clamping (n=99). Our main outcome was the time from birth to first exchange transfusions and/or transfusions. Secondary outcomes were hemoglobin level at birth, rate of exchange transfusion, number of postnatal transfusions, maximum bilirubin level, and number of phototherapy hours. Hemoglobin at birth was significantly higher in case of delayed cord clamping (mean difference, 1.7 g/dL; 95% confidence interval, 0.7-2.8). Among infants treated with exchange transfusion or transfusion, the time to initial treatment was higher in case of delayed cord clamping (median difference, 8 days; rate ratio, 1.51; 95% confidence interval, 1.09-2.10). There were no significant differences in the need for exchange transfusion, the number of transfusions, the maximum total bilirubin level, nor the number of phototherapy hours. In the subgroup analysis of neonates needing intrauterine transfusion during pregnancy (ie, severe alloimmunization), neonates had a lower rate of exchange transfusion in case of delayed cord clamping (odds ratio, 0.36; 95% confidence interval, 0.15-0.82). Our results indicate a benefit of delayed cord clamping in alloimmunization, regardless of pathology severity, without increased risk of jaundice.

Quality improvement review of O positive blood in emergency transfusion.

We recently introduced a policy to use O positive red cells in emergency transfusions for males >16 years of age and females >50 years of age. Here, we investigate changes in emergency transfusion practice and rates of red cell alloimmunization with the use of O positive blood for emergency transfusion. State-wide retrospective review of emergency transfusions between June 2020 and June 2021. The laboratory information system and patient medical records were used to collect demographic details, indications for transfusion, usage of O positive and O negative blood and rates of alloimmunization. There were 2354 red cell units transfused to 1013 patients (male = 59%, average age = 53 years) during the 12-month period. O positive units accounted for 46.9% (1103 units) of emergency transfusions. However, 726 (30.8%) O negative units were transfused to patients without a mandatory indication for O negative blood. Twenty-eight patients (2.9%) had a red cell alloantibody prior to transfusion including anti-E (n = 10), anti-D (n = 4), and anti-K (n = 4). One patient with prior anti-D had mild delayed hemolysis. There were 19 patients (4.3%, median follow-up 22 days) who developed a red cell alloantibody after emergency transfusion and include anti-E (n = 10), anti-D (n = 7), and anti-C (n = 5). The use of O positive blood for emergency transfusion has saved 1103 O negative red cell units with no detriment to patient outcome. There remains potential to optimize use of O positive blood in emergency transfusion and to understand red cell alloimmunization rates in a prospective fashion.

Increased red blood cell alloimmunization rates in transfused aplastic anemia and myelofibrosis patients.

Red blood cell (RBC) alloimmunization (AI) is a well-known complication of RBC transfusions, which results in the formation of alloantibodies to non-self antigens on donor RBCs, putting patients at risk of transfusion-related complications. The rate of AI with RBC transfusions in the general hospitalized population is estimated to be 2%-3%. However, some patients who are deemed "transfusion-dependent" require regular transfusions of blood products due to persistently low cell counts, putting them at even greater risk of RBC AI and increased morbidity. However, few studies currently exist investigating RBC AI in some transfusion-dependent patient populations, e.g., aplastic anemia (AA) and myelofibrosis (MF). We conducted a 5-year retrospective review to investigate the prevalence of RBC AI, alloantibody incidence, and the number of RBC transfusions in AA and MF patients, who received RBC transfusions within our hospital system. During the study period, 64 AA and 93 MF patients received 1301 and 2766 RBC transfusions, respectively. Compared to the RBC AI rate in the generalized hospitalized patient population (1%-2%), patients with AA and MF had an increased rate of RBC AI incidence rate at 14.1% and 12.9%, respectively. Furthermore, patients with primary MF demonstrated an isolated increased RBC AI incidence rate of 13.3%. The most common alloantibodies produced were anti-E and anti-K. Within our institution, patients with AA and MF had increased incidence rates of RBC AI compared to the general hospitalized patient population and may benefit from an antigen-matched protocol to minimize AI-related complications.

Proinflammatory state promotes red blood cell alloimmunization in pediatric patients with sickle cell disease.

We examined risk factors for RBC alloimmunization in pediatric patients with sickle cell disease (SCD), focusing on recipients' inflammatory state at the time of transfusion and anti-inflammatory role of hydroxyurea (HU). Among 471 participants, 55 (11.70%) participants were alloimmunized and formed 59 alloantibodies and 17 autoantibodies with an alloimmunization rate of 0.36 alloantibodies per 100 units. Analysis of 27 participants who formed alloantibodies with specificities showed 23.8% (30/126) of units transfused during a proinflammatory event resulted in alloantibody formation compared to 2.8% (27/952) of units transfused at steady state. Therefore, transfusion during proinflammatory events increased the risk for alloimmunization (odds ratio [OR]: 4.22; 95% confidence interval [CI]: 1.64-10.85; p = 0.003). Further analysis of all the 471 participants showed alloimmunization of episodically transfused patients who received transfusion mostly during proinflammatory events was not reduced by HU therapy (OR: 6.52; 95% CI: 0.85-49.77; p = 0.071), HU therapy duration (OR: 1.13; 95% CI: 0.997-1.28; p = 0.056) or HU dose (OR: 1.06; 95% CI: 0.96-1.16; p = 0.242). The analysis also identified high transfusion burden (OR: 1.02; 95% CI: 1.003-1.04; p = 0.020) and HbSS and HbSβ0-thalassemia genotypes (OR: 11.22, 95% CI: 1.51-83.38, p = 0.018) as additional risk factors for alloimmunization. In conclusion, the inflammatory state of transfusion recipients affects the risk of RBC alloimmunization, which is not modified by HU therapy. Judicious use of transfusion during proinflammatory events is critical for preventing alloimmunization.

Prevalence of Red Blood Cell Alloimmunization Among Pediatric Patients with Sickle Cell Disease in Saudi Arabia

Purpose: Sickle cell disease (SCD) is a common global hereditary hemoglobin disorder. One of the main treatments of sickle cell patients is the requirement of blood transfusions. Post transfusion alloimmunization of red blood cell antigens continue to be a major risk for SCD patients. The study objective is to determine the rate, nature, and risk factors of red cell alloimmunization among pediatric SCD patients in our center and compare our results to published reports from the KSA, regional and some international countries.
 Methodology: A retrospective study drsign was adopted with record review of SCD patients at King AbdulAziz Medical City-Jeddah (KAMC-J) between 2008-2019 where blood samples were analyzed for alloimmunization using immunohematological techniques. Demographic characteristics and transfusion history were recorded. Data analysis was conducted by SPSS ver. 26. Data are summarized as frequency distribution and chi square test was used to check significance of the difference in the frequency of alloantibodies among subgroups. 
 Findings: Out of all examined sickle cell patients (n=112). Alloantibodies were detected in 21 patients (17.4%), and these were mostly single in 15 patients (71.4%) as anti-K (23.7%), anti-E (19.0%), and anti-S (9.5%). The other six patients (28.6%) had multiple alloantibodies, especially the combination of anti-C and anti-K (9.5%) and the combination of anti-C and anti-E (9.5%). Alloantibodies were significantly higher in patients who had been admitted to the hospital > 5 times annually, those who had an exchange blood transfusion, age groups > 3 years, and for those who received a larger number of blood units (p-value < 0.05).
 Recommendations: The consequences of red blood cell alloimmunization are highly significant and, therefore, extended RBC antigens to include ABO, RH (D, C, c, E, e), K, Fya, Fyb, Jka and Jkb antigens in the screening panel for donors and recipients is highly recommended to ensure better transfusion practices and avoid transfusion related complications. Our rate of alloimmunization post frequent blood transfusion is considered relatively low compared to other nations.

Immunohematological evaluation of red cell alloimmunization and statistical assessment of various adsorption techniques in warm autoimmune hemolytic anemia

Adsorption techniques are widely applied to detect underlying masked alloantibodies in warm autoimmune hemolytic anemia (WAIHA). We established various adsorption techniques with an aim to detect alloimmunization in WAIHA This study conducted over a period of nine years included 298 patients of WAIHA. Complete immunohematological evaluation was performed on these 298 samples following departmental protocols. Clinical and laboratory details of patients were obtained from patient files. Various adsorption methods were performed and statistically evaluated in the study. Out of 479 cases of autoimmune hemolytic anemia, WAIHA comprised of 62.2 % (N = 298). A total of 139 (46.6 %) serum samples revealed autoantibodies. Adsorption study was performed in 101 (72.7 %) indicated samples and 24 (23.8 %) of these showed 26 alloantibodies. Among the patients subjected to adsorption study hemolytic marker were significantly deranged in the alloimmunization group (p < 0.01). Polyethylene glycol (PEG) adsorption was the quickest (52.2–54.6 min) of all adsorption techniques with minimum (1.3–1.5) numbers of adsorptions needing for complete removal of serum antibodies. The LISS-papain (LP) technique was found to be more sensitive and specific compared to the other two techniques. The agreement between PEG adsorption and LP adsorption was found to be ‘perfect’ (96.4 %) with a Cohen’s kappa (k) value of 0.9. We conclude that identification of alloantibody specificities underlying a warm autoantibody is critical for a safe and effective transfusion. All WAIHA patients with history of blood transfusion, pregnancy or both should be subjected to adsorption study. Selection of a suitable adsorption technique depends on multiple important factors.

Red Cell Alloimmunization and Antibody Specificity in Multigravida Attending Antenatal Clinic at Tertiary Care Centre from Rohilkhand Region

Introduction: Red cell alloimmunization is an immuneresponse to foreign red cell antigens which can occur due totransfusion between a donor and recipient, during pregnancybetween mother and fetus and also in transplant recipients.Such disparity may result in transfusion reactions or may beassociated with hemolytic disease of the fetus and newborn.The current study was undertaken to observe the prevalenceof red cell alloimmunization and antibody specificity inmultigravida patients with respect to epidemiological (age),obstetrical, major blood group systems and transfusion-relatedparameters.Material and Methods: This prospective cross-sectional studywas conducted over a period of 1.5 years from October 2018 toApril 2020, in the patients at risk of exposure to foreign red cellantigens in multigravida patients, in the blood bank of tertiarycare medical institute of North India.Antibody screening and identification was performed on 1055multigravida females using commercially prepared O cells(IMMUCOR, USA). Statistical evaluation by Chi-square testwas performed wherever applicable. p-value of &lt;0.05 wasconsidered statistically significant at 95% confidence interval.Results: Prevalence of red cell alloimmunization inmultigravida females was 1.99% with anti-D being the mostcommon antibody identified. Other less commonly detectedalloantibodies were anti-E, anti-Jkb (Kidds) and anti-Kpa (Kell).A statistically significant association was found between red cellalloimmunization and increase in gravida status, presence ofbad obstetric history, age (&gt;30 years) and Rh-D status. Whencompared with other independent variables such as parityand ABO blood group of the female, no statistical significantassociation was observed.Conclusion: Maternal alloimmunization is associated withanti-D specificity and antibodies against other clinicallysignificant minor blood group antigens such as anti-E andanti-Jkb (Kidd) and anti-Kpa (Kell). Routine antibody screeningof all antenatal females, irrespective of the Rh-D status mustbe adopted by health care system for detection of clinicallysignificant antibodies that may be associated with HDFN ordelayed hemolytic transfusion reaction.

Alloimmunization in children with sickle cell disease: A tertiary care experience

IntroductionPatients with sickle cell disease (SCD) show a high prevalence of red blood cell (RBC) alloimmunization, however, few studies have focused on children. The present study was undertaken to determine the prevalence of alloimmunization and autoimmunity in children with SCD and to assess any correlation with age, number of transfusions received, and the number and frequency of crisis. Material & methodsSixty children affected with homozygous SCD, aged between five to eighteen years and having received more than one packed red blood cell (PRBC) transfusion were enrolled in the study.The preliminary tests included antiglobulin test (indirect and direct), alloantibody screening by three panel, antibody typing using 11 panel and auto-control test to detect autoantibodies. ResultsDirect antiglobulin test was negative in all the 60 patients, whereas indirect antiglobulin test was positive in 4/60 (6.6%) patients. Specific typing of alloantibodies revealed anti-D and anti-Kell antibodies in 2 (3.3%) each. Patients with alloantibody (4) had a higher mean age at onset of first symptom (7.05 ± 2.12 years) and age at first transfusion (7.5 ± 2.12 years) as compared to those without alloantibody, (4.48 ± 3.09 and 4.91 ± 3.12 years respectively). Patients with alloantibody received more PRBC transfusions, maintained low hemoglobin, required higher doses of hydroxyurea and also had a larger liver and spleen. ConclusionThe present study found a low prevalence of antibodies in patients with SCD. Patients presenting with symptoms of SCD at younger age received hydroxyurea at an earlier age. Starting hydroxyurea at an earlier age may decrease subsequent alloantibodies development. Larger studies to compare groups of patients related to administration of hydroxyurea are required to confirm this hypothesis.

Immunohematological challenges in COVID infected patients

BackgroundSeveral autoimmune disorders have been reported to be related with COVID infection. In continuation to these autoimmune phenomenon, autoimmune hemolytic anaemia (AIHA) also has been noted in COVID infected patients. The aim of the study was to find out the prevalence of red cell alloimmunization, ABO discrepancy and positive direct antiglobulin test (DAT) results in COVID infected patients hospitalised in a tertiary care centre in North India. MethodologyThis was a retrospective observational study done from July 2020 to June 2021. All symptomatic patients admitted to ICU tested positive for SARS CoV-2 whose blood samples were received in the immunohematology laboratory of department of Transfusion Medicine for determination of blood group and issue of packed red cells, and found to have positive antibody screen, blood group discrepancy and positive DAT results, were included in the study. ResultsA total of 10,568 tests were run, out of which 4437 were for determination of blood group, 5842 were for antibody screen and 289 were for direct antiglobulin test. Included in this study were 146 patients who either had blood group discrepancy, or had a positive antibody screen or had a positive DAT. Out of 115 positive antibody screen, 66 patients had only alloantibodies, 44 patients had only autoantibodies while only 5 patients had both auto as well as alloantibodies. Total number of positive DAT cases was 50 (50/289 = 17.3 %). There were 26 ABO discrepancies (26/4437 =0.58 %) found. ConclusionOur results also indicate that there is rise in rate of alloimmunization and DAT positivity among COVID patients.

Red blood cell alloimmunizations in thalassaemia patients with regular transfusion in China: A systematic review and meta-analysis.

The development of red blood cell alloimmunization intensifies transfusion complication in thalassaemia patients. The purpose of this paper is to evaluate the existing evidence on the prevalence of erythrocyte alloimmunization in China by meta-analysis. We systematically searched cross-sectional studies regarding the alloimmunization of thalassaemia patients with regular blood transfusion in China from year 2000 to May 2021 in the Cochrane library, PubMed, EMBASE, Web of Science, and Chinese databases including CNKI, Wanfang Data, Vip and CBM. Data extraction and quality evaluation of the included studies were performed. Meta-analysis was performed using the DerSimonian and Laird random-effects models with inverse variance weighting. The presence of publication bias was tested by Egger's test, and the methodological quality of each included article was evaluated by the criteria specific to prevalence studies. A total of 1874 patients and 263 alloantibodies from 11 studies were identified and included in the meta-analysis. The proportion of alloantibodies against antigens belonging to the Rh, MNSs and Kidd systems were as high as 70.3%, 17.9%, and 6.5%, respectively. Meta-analysis showed that the overall prevalence of alloimmunization among transfusion-dependent thalassaemia patients in China is 11.4% (95%CI: 7.2%∼16.3%). The characteristics of red blood cell alloimmunization among thalassaemia patients with regular transfusion in China differ greatly from those in other countries. Therefore, transfusion strategies shall be actively adapted in line with thalassaemia patients in China to minimize the risk of alloimmunization.

Red Blood Cell Alloimmunization and Autoimmunization in Blood Transfusion-Dependent Sickle Cell Disease and β-Thalassemia Patients in Al-Ahsa Region, Saudi Arabia.

The risk of developing transfusion-related complications, especially alloimmunization, is an ongoing concern for transfusion-dependent patients. It is important to determine the rate of alloimmunization and autoimmunization in Al-Ahsa Region, Saudi Arabia, where sickle cell disease (SCD) and thalassemia incidence rates are the highest in Saudi Arabia. A cross-sectional study was conducted to review the transfusion history of patients with SCD and thalassemia at the King Fahad Hospital (KFH) in Al-Ahsa, Saudi Arabia. 364 transfusion-dependent patients were included in this study. Alloimmunization rates in patients with SCD and thalassemia were 16.7% and 11.97%, respectively, while autoimmunization rates in patients with SCD and thalassemia were 5.3% and 0.7%, respectively. The most frequent alloantibodies among the study participants were against Kell, Rh blood group systems. Blood transfusion-related alloimmunization and autoimmunization compromise the proper management of chronically transfused patients. Ideally, extended matched phenotyping should be implemented to prevent alloimmunization and reduce the risk of developing blood transfusion-related alloantibodies.

Study of the Frequency and Specificity of Red Cell Antibodies in Patients with Hemoglobinopathies

Patients with thalassemia and sickle cell disease (SCD) require blood transfusions as part of their supportive care. However, one of the most serious side effects of this treatment is the risk of red cell alloimmunization. The goal of this study was to assess the prevalence and Specificity of red cell alloimmunization in Egyptian thalassemia and sickle cell anaemia patients. This study included 200 multi transfused Egyptian patients, one hundred and forty patients with transfusion dependent thalassaemia and sixty patients with sickle cell anaemia, who were attending the Paediatric Children Hospital-Cairo University at the period from March 2019 to October 2019. Alloantibody identification was made by Diamed- ID microtyping system. In the studied groups both thalassemia and sickle patients, the prevalence of alloimmunization was 22/200 (11%) patients. The two most often alloantibodies were, antibodies against Kell antigen (37%) and against E antigen (30%). The prevalence of alloimmunization was more in females in comparison to males, but it did not reach statistical significance and patients with thalassemia major had higher alloimmunization rates than other studied groups but was not statistically significant. In the D negative patients in the research group, alloimmunization demonstrated a statistically significant difference (p = 0.01). Age, gender, age of transfusion onset and splenectomy were not contributing factors to the antibody presence in the group of patients being investigated. Before receiving blood transfusions, extended red blood cell phenotyping should be thought of as a crucial procedure for hemoglobinopathies patients who would likely have several transfusions. It is advised that haemoglobinopathies patients in Egypt be checked through phenotyping of RBC units for Kell and all Rh antigens to be phenotyped before starting transfusion in these patients which is also standard of care for these patients presently.

Fetal and neonatal outcome in severe alloimmunization managed with intrauterine transfusion: 18-year experience in a tertiary referral hospital in China.

Hemolytic disease of the fetus and newborn (HDFN) due to red cell alloimmunization, is an important cause of fetal and neonatal morbidity and mortality. However, fetal and neonatal outcome of HDFN managed with intrauterine transfusion (IUT) in China are unknown. In addition, fetal and neonatal outcomes according to the type of maternal red cell alloantibodies involved and outcomes of hydrops fetalis are also unclear. The objective of this study was to evaluate fetal and neonatal outcomes of severe red-cell alloimmunization treated by IUT, to compare the outcomes according to the type of antibody, and to investigate the perinatal and postnatal outcomes of hydrops fetalis due to red cell alloimmunization. A retrospective study of pregnancies affected by HDFN and managed with IUT at a tertiary care university hospital in China between January 2001 and December 2018 was performed. Fetal and neonatal outcomes were investigated, and comparison of outcomes depending on the type of antibody and comparison of outcome between hydrops fetalis and fetuses without hydrops were also conducted. 244 IUTs were performed in 81 fetuses from 80 pregnancies. Anti-RhD was the major etiology of HDFN requiring IUT (71.6%). The fetal survival rate was 90.1%. The survival rate of the hydropic fetuses was significantly lower than those of the non hydropic fetuses (61.2% vs. 95.6%) (P = 0.002**). Compared with non hydropic fetuses, hydropic fetuses had significantly lower gestational age and lower hemoglobin level at first IUT. The neonatal survival rate was 98.6%. Exchange transfusions were required in 26% of the neonates. 30.1% of neonates had late anemia and required top-up transfusions, and hydropic fetuses required more late top-up transfusions than fetuses without hydrops. No significant difference in fetal and neonatal outcomes was found among the four subgroups stratified by the antibody involved. Our study demonstrates that IUT is an effective and safe therapy for severe HDFN at our institution. Early detection and treatment of hydrops is critical for perinatal outcomes. Particular attention should be paid to late postnatal anemia in affected neonates and top-up transfusion is still commonly needed.

Associated Factors of Red Blood Cell Alloimmunization among Solid Cancer Patients in Teaching Hospital in Malaysia

Background: Alloimmunization is a known complication following repeated red blood cell transfusions. However, the associated factors of RBC alloimmunization are different among blood recipient groups. This study aimed to determine the associated factors of red blood cell alloimmunization among solid cancer patients in Hospital USM. Material and Methods: This cross-sectional study involved 322 adult solid cancer patients screened for red cell alloantibodies in our centre from October 2016 until February 2019. The clinical and transfusion data were obtained from the patient’s medical record and laboratory information system (My Transfusi). The multiple logistic regression was used for analysis of potential associated factors of red blood cells alloimmunization, and p-value of less than 0.050 was considered statistically significant. Results: The patient’s mean age was 52.0 years old, with the majority were Malays (91.0%) and females (61.2%). The most common cancers were breast (32.3%) followed by gastrointestinal (16.8%) and head and neck (14.3%). The presence of metastases (adjusted OR=13.53, p=0.017), numbers of packed red cell transfusions (adjusted OR=1.12, p= 0.015), and blood group A (adjusted OR=7.45, p=0.003) were the associated factors of alloimmunization. Conclusions: Solid cancer patients with metastases, received a higher number of packed red cell transfusions, and blood group A were at higher risk for alloimmunization. Strategies to provide phenotype RBC should focus on this type of patient to prevent red blood cells alloimmunization in solid cancer patients. Bangladesh Journal of Medical Science Vol. 22 No. 02 April’23 Page : 379-384

Non‐immune hydrops fetalis: a practical guide for obstetricians

Key content Hydrops fetalis is the accumulation of two or more fetal fluid collections, including pericardial effusion, pleural effusion(s), ascites and skin oedema. In the absence of red cell alloimmunisation, hydrops fetalis is non‐immune and affects approximately 1 in 2000 pregnancies. Non‐immune hydrops fetalis (NIHF) is associated with severe perinatal morbidity/mortality and significant maternal risks, including maternal mirror syndrome. Priorities for clinicians are determining the cause antenatally to optimise management and discuss treatment options, if available. Systematic reviews have indicated that a cause can be identified prenatally in ~60% cases. Recent evidence indicates fetal exome sequencing can provide a diagnosis in 30% of previously unexplained cases. Learning objectives To understand causes of NIHF and its association with perinatal and maternal morbidity and mortality To appreciate the basis for investigations for NIHF, including exome sequencing To understand how care can be effectively shared by referring units and tertiary fetal medicine units

Red Blood Cell Alloimmunization and Its Associated Factors among Chronic Liver Disease Patients in a Teaching Hospital in Northeastern Malaysia

Red blood cell (RBC) alloimmunization is an important complication of blood transfusion. Variations in the frequency of alloimmunization have been noted among different patient populations. We aimed to determine the prevalence of RBC alloimmunization and associated factors among chronic liver disease (CLD) patients in our center. This is a case-control study involving 441 patients with CLD who were being treated at Hospital Universiti Sains Malaysia and subjected to pre-transfusion testing from April 2012 until April 2022. Clinical and laboratory data were retrieved and statistically analyzed. A total of 441 CLD patients were included in our study, with the majority being elderly, with the mean age of patients 57.9 (SD ± 12.1) years old, male (65.1%) and Malays (92.1%). The most common causes of CLD in our center are viral hepatitis (62.1%) and metabolic liver disease (25.4%). Twenty-four patients were reported to have RBC alloimmunization, resulting in an overall prevalence of 5.4%. Higher rates of alloimmunization were seen in females (7.1%) and patients with autoimmune hepatitis (11.1%). Most patients developed a single alloantibody (83.3%). The most common alloantibody identified belonged to the Rh blood group, anti-E (35.7%) and anti-c (14.3%), followed by the MNS blood group, anti-Mia (17.9%). There was no significant factor association of RBC alloimmunization among CLD patients identified. Our center has a low prevalence of RBC alloimmunization among CLD patients. However, the majority of them developed clinically significant RBC alloantibodies, mostly from the Rh blood group. Therefore, phenotype matching for Rh blood groups should be provided for CLD patients requiring blood transfusions in our center to prevent RBC alloimmunization.

Rhesus (Rh) blood group antigens in multiparous women attending antenatal clinic in tertiary hospital, port harcourt, Nigeria

The routine blood screening test carried out for pregnant women attending antenatal clinic in Tertiary Hospital Port Harcourt, Nigeria especially with regards to blood group system is limited to ABO/Rh D antigen screening. This cross-sectional, hospital-based study was aimed at determining the prevalence of the Rh C, c, E and e blood group antigens in multiparous women attending antenatal clinic in Tertiary Hospital Port Harcourt, Nigeria. A total of one hundred and twenty (120) pregnant females within the age range of 18-40years were recruited randomly into the study between February-June, 2022. Blood samples were aseptically collected by venipuncture into EDTA sample bottle; Rh C, c, E and e blood group antigens were assay for using microwell agglutination technique. Data generated was statistically analyzed by simple percentage calculation and defining the percentage frequency of Rh antigens. Results obtained showed the percentage distribution of 17.5% for Rh C, 89.2% for Rh c, 39.2% for Rh E and 90.8% for Rh-e. Percentage distribution of Rh antigens amongst studied population based on parity showed that G3P2 group had the highest percentage positivity of 8(6.7%) for Rh-C antigen while those carrying their first pregnancy (prime) had the highest percentage positivity of 33(27.5%), 15(12.5%) and 36(30.0%) for Rh-c, Rh-E and Rh-e respectively. Distribution of Rh antigens with respect to previous transfusion history in studied participants showed 6 (5.0%), 15 (12.5%), 6 (5.0%) and 17 (14.2%) percentage positivity for Rh-C, Rh-c, Rh-E and Rh-e respectively. This study revealed a percentage positivity of 17.5%, 89.2%, 39.2 % and 90.8% for Rh-C, Rh-c, Rh-E and Rh-e respectively with high percentage expression for Rh-c, E and e antigens found on the red cells of Antennal Women carrying their first pregnancy. Furthermore, there is a high percentage expression of Rh antigens in previously transfused pregnant women in this study. Although routine phenotyping of these blood group antigens will be a financial burden in a resource limited country like Nigeria. It is expedient and needful to take into cognizance the fact that the presence of Rh C, c, E and e antigens may likely be the cause of some delayed transfusion reactions and haemolytic disease of the foetus and new born. Therefore, there is need for the inclusion of Rh C, c, E and e in routine antigen typing for pregnant women in other to help ameliorate red blood cell alloimmunization and delayed haemolytic transfusion reaction during pregnancy. Furthermore, there is need to promulgate policies that promote the optimum stocking of Rh-e, c antigen negative blood in blood banks in the area for emergency use.

A Retrospective Cohort Study of Red Cell Alloimmunisation in Rural, Remote, and Aboriginal and Torres Strait Islander Peoples Admitted to Intensive Care in the Northern Territory, Australia.

Red cell (RC) alloantibodies occur on exposure to non-self RC antigens in transfusion and pregnancy (typically IgG and clinically significant) or in association with non-RC immune environmental factors (typically IgM and not clinically significant). In Australia, the risk of RC alloimmunisation in First Nations peoples is unknown. We assessed the epidemiology, specificity, and antecedents of RC alloimmunisation via a data linkage retrospective cohort study of Northern Territory (NT) intensive care unit (ICU) patients (2015-2019). Of 4183 total patients, 50.9% were First Nations. In First Nations versus non-First Nations patients, the period prevalence of alloimmunisation was 10.9% versus 2.3%, with 390 versus 72 prevalent alloantibodies detected in 232 versus 48 alloimmunised patients, of which 135 (34.6%) versus 52 (72.2%) were clinically significant specificities. Baseline and follow-up alloantibody testing were available for 1367 patients, in whom new incident clinically significant alloantibodies developed in 4.5% First Nations versus 1.1% non-First Nations patients. On Cox proportional hazards modelling, adjusted hazard ratios (HR) showed First Nations status (HR 2.67 (95% CI 1.05-6.80), p = 0.04) and cumulative RC unit transfusion exposure (HR 1.03 (95% CI 1.01-1.05), p = 0.01) were independent predictors of clinically significant alloimmunisation. First Nations Australian patients are at increased risk of alloimmunisation due to RC transfusion, underscoring the importance of very judicious use of RC transfusions and shared decision-making with patients. Further studies are recommended to explore the role of other (non-RC) immune host factors, given the relative high prevalence of non-clinically significant IgM alloantibodies within alloimmunised First Nations patients.