Neonatal hemolytic disease: How should we use indirect and direct antiglobulin tests?

BACKGROUND: In newborns with hemolysis, the direct antiglobulin test (DAT) and indirect antiglobulin test (IAT) play a key role in demonstrating the presence of an immune cause. We aimed to emphasize the importance of IAT in mothers of DAT-positive babies. METHODS: DAT was performed with forward blood grouping on cord blood in term babies who were born between September 2020 and September 2022. IAT was performed in the mothers of the babies who were found to have a positive DAT and antibody identification was performed in the mothers who were found to have a positive IAT. Specific antibodies detected and identified were associated with the clinical course. RESULTS: The study included 2769 babies and their mothers. The prevalence of DAT positivity was found to be 3.3% (87 of 2661). In DAT-positive babies, the rate of ABO incompatibility was 45.9%, the rate of RhD incompatibility was 5.7% and the rate of RhD and ABO incompatibility in association was 10.3%. The rate of subgroup incompatibility and other red blood cell antibodies was 18.3%. Phototherapy was applied because of indirect hyperbilirubinemia in 16.6% of the DAT-negative babies and in 51.5% of the DAT-positive babies. The need for phototherapy was significantly higher in DAT-positive infants (p < 0.01). Severe hemolytic disease of the newborn, bilirubin level, duration of phototherapy and use of intravenous immunoglobulin were found to be significantly higher in the babies whose mothers were IAT positive compared with the babies whose mothers were IAT negative (p < 0.01). CONCLUSIONS: IAT should be performed on all pregnant women. When screening with IAT is not performed during pregnancy, performing DAT in the baby plays a key role. We showed that the clinical course was more severe when mothers of DAT-positive babies were IAT positive.

Significance of immunohematologic testing in mother and newborn ABO incompatibility.

The aim of this study was to define risk factors for jaundice and anemia in newborns with a positive direct antiglobulin test (DAT) and/or with an incompatible crossmatch due to ABO incompatibility between mother and newborn. ABO incompatibility has become a more significant cause of hemolytic disease of the fetus and newborn since the introduction of effective anti-D prophylaxis. The condition is common and, if clinically significant at all, causes only mild jaundice, which can be treated with phototherapy (PT). However, rare and serious presentations, requiring transfusion therapy, have been noted. Clinical, laboratory, and immunohematologic data were collected retrospectively from medical records of ABO-incompatible newborns and their mothers over a 5-year period (2016-2020) from University Hospital Centre Zagreb. Two groups of newborns were compared: those who needed medical intervention because of hyperbilirubinemia or anemia and those who did not. Within the group of newborns requiring intervention, we also compared those with A and B blood groups. Over the 5-year period, 72 of 184 (39%) newborns required treatment. The treatment was PT in 71 (38%) newborns and erythrocyte transfusion in 2 (1%). In 112 (61%) newborns, ABO incompatibility was an accidental finding while performing blood group typing; these newborns did not require any therapy. In conclusion, we found a statistical, but not clinically significant, difference between the groups of treated and untreated newborns, related to the mode of delivery and DAT positivity within hours of delivery. There were no statistically significant differences in characteristics between the groups of treated newborns, except for two newborns with blood group A who received erythrocyte transfusions.

Clinical value of combination detection of direct antiglobulin test and serum albumin globulin ratio in severe hyperbilirubinemia caused by ABO hemolytic disease of the newborn.

Background To explore of a combination of antiglobulin test(DAT) and albumin globulin ratio(AGR) could predict the severity of ABO hemolytic disease of the newborn(ABO-HDN).Methods The measurement of DAT, AGR and combination detection of DAT and AGR was done to predict severe ABO-HDN hyperbilirubinemia in 270 full-term infants based on whether the infants received transfusions of blood components. The infants were divided into three groups according to the results of DAT and ARG and compared the differences of phototherapy day and hospitalization day of the three groups.Results Of the 270 cases enrolled in this study, 69 infants were DAT positive. Peak total bilirubin, AGR, and positive DAT were independently associated with the need for blood components transfusion. ROC curve analysis for blood components transfusion showed that DAT cutoff value >± with a sensitivity of 39.4% and a specificity of 83.9%, AGR cutoff value <2.05 with a sensitivity of 54.1% and a specificity of 85.7%, and combination detection of DAT and ARG with a sensitivity of 62.1% and a specificity of 91.2%. The AUCs for DAT, AGR, and combination detection of DAT and AGR were .621, .740, and .750 respectively. The phototherapy day and hospitalization day were significantly longer in group of AGR <2.05 and DAT >± than that of a group of AGR <2.05 and group of DAT >±.Conclusions DAT and ARG could be early predictors for the severity ABO-HDN hyperbilirubinemia and combination detection of DAT and AGR could further increase its predictive value.

A Rare Case of Hemolytic Disease of the Fetus and Newborn Caused by Anti-s Antibody in a Chinese Patient.

BACKGROUND: Anti-s is a rare alloantibody, and the reported cases of hemolytic disease of the fetus and newborn (HDFN) caused by anti-s are limited to non-Asian populations. METHODS: Here, we report the case of a Chinese woman with a history of multiple pregnancies who developed an alloantibody with anti-s specificity. RESULTS: Her newborn developed HDFN caused by anti-s but the clinical symptoms were not serious. After supportive treatment and bilirubin light phototherapy, the baby was discharged with a good prognosis. CONCLUSIONS: This is the first reported case of anti-s-induced HDFN in a Chinese patient, highlighting the need for further research in the Asian population.

Hemolytic disease of the fetus and newborn mediated by anti-Dia in a U.S. hospital.

Dia is one of the most clinically significant low-prevalence antigens in the Diego blood group system, since antibodies to Dia have, albeit rarely, been implicated in hemolytic transfusion reactions and hemolytic disease of the fetus and newborn (HDFN). Given the geographical association, most anti-Dia HDFN cases have been reported in Japan, China, and Poland. We describe a case of HDFN in a neonate born to a 36-year-old G4P2012 woman of self-identified Hispanic ethnicity and of South American descent with multiple negative antibody detection tests in a U.S. hospital. Upon delivery, a cord blood direct antiglobulin test was positive (3+ reactivity), and neonatal bilirubin levels were moderately elevated, but phototherapy and transfusion were not required. This case highlights a rare, unexpected cause of HDFN in the United States secondary to anti-Dia, given the near-universal absence of this antigen and antibody in most U.S. patient populations. The case also demonstrates the need for awareness of antibodies to antigens that are considered "low-prevalence" in most populations but that might be encountered more frequently in specific racial or ethnic groups and may require more extensive testing.

History and current standard of postnatal management in hemolytic disease of the fetus and newborn.

Since the discovery of the Rh blood group system in 1940, a greater understanding of hemolytic disease of the fetus and newborn (HDFN) was gained. In the years thereafter, researchers and clinicians came to the current understanding that fetal and neonatal red blood cells (RBC) are hemolyzed by maternal alloantibodies directed against RBC antigens potentially leading to severe disease. Preventative measures, such as Rhesus(D) immunoprophylaxis (RhIG), have greatly decreased the prevalence of Rh(D)-mediated HDFN, although a gap between high-income countries and middle- to low-income countries was created largely due to a lack in availability and high costs of RhIG. Other important developments in the past decades have improved the identification, monitoring, and care of pregnancies, fetuses, and neonates with HDFN. Prenatally, fetal anemia may occur and intrauterine transfusions may be needed. Postnatally, pediatricians should be aware of the (antenatally determined) risk of hemolysis in RBC alloimmunization and should provide treatment for hyperbilirubinemia in the early phase and monitor for anemia in the late phase of the disease. Through this review, we aim to provide an overview of important historic events and to provide hands-on guidelines for the delivery and postnatal management of neonates with HDFN. Secondarily, we aim to describe recent scientific findings and evidence gaps. CONCLUSION:  Multiple developments have improved the identification, monitoring, and care of pregnancies and neonates with HDFN throughout the centuries. Pediatricians should be aware of the (antenatally determined) risk of hemolysis in RBC alloimmunization and should provide treatment for hyperbilirubinemia in the early phase and monitor for late anemia in the late phase of the disease. Future studies should be set in an international setting and ultimately aim to eradicate HDFN on a global scale. WHAT IS KNOWN: • Developments have led to a greater understanding of the pathophysiology, an improved serological identification and monitoring of at-risk cases and the current pre- and postnatal treatment. WHAT IS NEW: • This review provides the pediatrician with hands-on guidelines for the delivery and postnatal management of neonates with HDFN. • Future studies should be set in an international setting with the ultimate aim of eradicating HDFN.

From A to AB: A Caucasian Mother with High Anti-B Titer Causing Hemolytic Disease of the Newborn.

We report on a term infant with clinically significant hemolysis and hyperbilirubinemia. Testing revealed ABO incompatibility between maternal type A and infant type AB. The maternal alloantibody screen was negative. The infant's direct antiglobulin test was positive, and anti-B IgG was eluted off the infant's red blood cells (RBCs). Testing of the mother's plasma revealed a high anti-B titer. The infant was successfully treated with phototherapy and intravenous immunoglobulin. The bilirubin and hematocrit stabilized, and the infant was discharged home. This case was unusual because of its severity and unusual ABO constellation. Furthermore, this report is an exemplary educational case study on how effective collaboration between the clinical team and the blood bank laboratory is critical in reaching the correct diagnosis. In summary, the differential diagnosis of more unusual and atypical ABO-incompatible constellations must be considered when an infant presents with unexplained hemolysis.

Management and clinical consequences of red blood cell antibodies in pregnancy: A population-based cohort study.

INTRODUCTION: Anti-D alloimmunization is the most common cause of severe hemolytic disease of the fetus and newborn (HDFN). The management of pregnancies affected by less frequent red blood cell (RBC) antibodies poses a challenge to clinicians, and perinatal outcomes are less well described. This study aimed to describe the frequency of clinically significant RBC antibodies in our pregnant population and analyze the risk of prenatal and postnatal treatment for HDFN in relation to our national risk classification system and management guidelines. MATERIAL AND METHODS: A retrospective cohort study in the population of all alloimmunized singleton pregnancies in the Stockholm region 1990-2016. Descriptive summaries of different RBC antibodies and pregnancy outcomes were presented, the risks of intrauterine blood transfusion (IUT) and neonatal treatment for HDFN were estimated by type of antibodies. RESULTS: Of the 1724 alloimmunized pregnancies, 1079 (63%) were at risk of HDFN and constituted our study cohort. Anti-D was detected in 492 (46%) pregnancies, followed by anti-E in 161 (15%), and anti-c in 128 (12%). Eighty-seven (8%) pregnancies had IUT, with the highest risk in pregnancies affected by anti-D combined with other antibodies. The maximum titer recorded before IUT was 64 or above, except for two pregnancies affected by anti-c, for which the maximum titers were 8 and 16. For the 942 (95%) live-born neonates from 992 alloimmunized pregnancies without IUT, the median gestational age at birth was 38+5  weeks compared with 35+5  weeks for those who had IUT. Neonatal treatment was most common in the anti-D alone and anti-D combined groups, with 136 (57%) and 21 (44%), respectively, treated with phototherapy and 35 (15%) and 9 (20%) receiving exchange transfusions, respectively. For pregnancies complicated by moderate- and low-risk antibodies, phototherapy was less frequent (32 [36%] and 21 [19%]) and exchange transfusion was rare (5 [6%] and 3 [3%]). CONCLUSIONS: Anti-D, especially in combination with other antibodies, presents the highest risk of severe HDFN. The classification of less frequent and less well-known RBC antibodies into risk groups can help clinicians in assessing the risk of HDFN and counseling alloimmunized pregnant women regarding the risk of prenatal and postnatal treatments.

Hemolytic Disease of the Fetus and Newborn Caused by Maternal Autoantibody with Mimicking Anti-E Specificity.

OBJECTIVE: There are few reports of hemolytic disease of the fetus and newborn (HDFN) caused by maternal autoantibodies. METHODS: We describe the case of a pregnant patient aged 26 years with systemic lupus erythematosus without any transfusion history who developed autoantibody with mimicking anti-E specificity. Her newborn developed HDFN caused by the maternal autoantibody. RESULTS: The clinical symptoms of the newborn were not serious. After bilirubin light phototherapy and other symptomatic supportive treatment, the baby was discharged with a good prognosis. CONCLUSION: This is the first reported case of HDFN caused by maternal autoantibody with mimicking anti-E specificity. However, the real antigenic target of the autoantibody was not clear.

[Remote monitoring of neonatal jaundice in newborns with ABO hemolytic disease].

OBJECTIVE: To explore the feasibility of remote monitoring of neonatal jaundice in newborns with ABO hemolytic disease. METHODS: Forty six neonates of gestational age >35 weeks with ABO hemolytic disease admitted to Women's Hospital, Zhejiang University School of Medicine from January 20th, 2020 to February 29th, 2020 were enrolled in the study (study group). The newborns were followed up at home after discharge, the transcutaneous bilirubin (TCB) levels were measured by parents using the provided device and the results were sent to the doctor by smart phone using the installed APP. Fifty six newborns with ABO hemolytic disease admitted in 2018 who received conventional outpatient follow-up after discharge served as the control group. The demographic characteristics, total serum bilirubin (TSB) level during hospitalization, number of outpatient visit and rate of re-admission due to rebound hyperbilirubinemia were compared between the two groups. RESULTS: There were no significant differences between the two groups in gestational age, birth weight, delivery mode, gender, length of the first hospitalization, TSB level before phototherapy and before discharge, and the managements during the first hospitalization (all P>0.05). Compared with the control group, TSB level before readmission [(265±16) µmol/L vs. (295±15) µmol/L] and the number of outpatient visits (1.3±0.8 vs. 3.8±0.5) were significantly lower in the study group (all P<0.01), while the rate of readmission (17.4%vs. 12.5%) and the weight at the time of readmission[(3398±452) g vs. (3477±324) g] were not significantly different (all P>0.05). No cases of acute bilirubin encephalopathy occurred in both groups. CONCLUSIONS: The remote follow-up for neonatal jaundice at home can effectively reduce the number of outpatient visits without increasing the risk of readmission and severe neonatal hyperbilirubinemia for newborns with ABO hemolytic disease.

A case of mild HDFN caused by anti-C, anti-D, and anti-G: Diagnostic strategy and clinical significance of distinguishing anti-G from anti-D and anti-C.

Anti-G is commonly present with anti-D and anti-C and can confuse serological investigations. The differentiation of anti-G from anti-D and anti-C is particularly essential for the accurate diagnosis of hemolytic disease of the fetus and newborn (HDFN) and appropriate administration of anti-D immunoglobulin prophylaxis in Rhesus (Rh) negative women. We reported a rare case of anti-G together with anti-D and anti-C in a pregnant woman and her female neonate. The titers of IgG anti-D, anti-C, and anti-G in the woman were 256, 128, and 32, respectively. While the titers of IgG anti-D, anti-C, and anti-G in the neonate were 16, 8, and 4, respectively. The neonate experienced mild HDFN and only received phototherapy during hospitalization. This report discusses the diagnostic strategy and clinical significance of differentiating anti-G from anti-D and anti-C.

Remote monitoring of neonatal jaundice in newborns with ABO hemolytic disease / 浙江大学学报·医学版

OBJECTIVE@#To explore the feasibility of remote monitoring of neonatal jaundice in newborns with ABO hemolytic disease.@*METHODS@#Forty six neonates of gestational age >35 weeks with ABO hemolytic disease admitted to Women's Hospital, Zhejiang University School of Medicine from January 20th, 2020 to February 29th, 2020 were enrolled in the study (study group). The newborns were followed up at home after discharge, the transcutaneous bilirubin (TCB) levels were measured by parents using the provided device and the results were sent to the doctor by smart phone using the installed APP. Fifty six newborns with ABO hemolytic disease admitted in 2018 who received conventional outpatient follow-up after discharge served as the control group. The demographic characteristics, total serum bilirubin (TSB) level during hospitalization, number of outpatient visit and rate of re-admission due to rebound hyperbilirubinemia were compared between the two groups.@*RESULTS@#There were no significant differences between the two groups in gestational age, birth weight, delivery mode, gender, length of the first hospitalization, TSB level before phototherapy and before discharge, and the managements during the first hospitalization (all @*CONCLUSIONS@#The remote follow-up for neonatal jaundice at home can effectively reduce the number of outpatient visits without increasing the risk of readmission and severe neonatal hyperbilirubinemia for newborns with ABO hemolytic disease.

Anemic Disease of the Newborn With Little Increase in Hemolysis and Erythropoiesis Due to Maternal Anti-Jra: A Case Study and Review of the Literature.

The severity of the hemolytic disease of the fetus and newborn (HDFN) due to Jra mismatch ranges from no symptoms to severe anemia that requires intrauterine and exchange transfusions. We encountered a newborn, born to a healthy mother having anti-Jra at 38 weeks of pregnancy, who had moderate anemia, a positive direct antiglobulin test (DAT) result, no increased erythropoiesis, and no jaundice at birth. Flow cytometry revealed that the Jra antigen of red cells in the infant was nearly negative at birth, biphasic at 5 weeks, and lowly expressed at 7 months of life. We searched online for previous case reports on HDFN due to Jra incompatibility. Among 63 reported cases, excluding 25 cases, 38 were included with the present case for analysis. Of 39 newborns, 10 developed clear anemia (hemoglobin <10.0 g/dL), and 1 died, 5 developed hydrops fetalis, 4 needed intrauterine transfusion and/or exchange transfusion, and 3 received red cell transfusion after birth; overlaps were included. Among 29 neonates with no anemia, 8 needed interventions including phototherapy and γ-globulin infusion, and the remaining 21 received conservative supports only. The maternal anti-Jra titer, ranging between 4 and 2048, did not correlate with the severity of anemia, levels of bilirubin, or any interventions required. The DAT of red cells was positive in 29 of 36 fetuses/newborns tested, whereas it was often negative among anemic neonates (4 of 9) (P < .05). Hematopoiesis did not increase effectively, as indicated by reticulocyte ratios between 1.7% and 22.3%, even with the increase in reticulocytes in anemic neonates compared with nonanemic neonates (P < .05). Total bilirubin levels ranged broadly between 0.2 and 14.3 mg/dL but were generally low. The maternal anti-Jra titer and IgG3 subclass did not correlate with the morbidity of the newborns. Being identical/compatible between mothers and their infants may possibly enhance infants' morbidity, as a weak tendency was observed (P = .053). Maternal anti-Jra may suppress erythropoiesis in fetuses via a mechanism different from the established HDFN, such as anti-D, as evidenced by the lower reticulocyte count and small increase in bilirubin in neonates. As the anti-Jra titer, IgG subclass, and DAT were not correlated with the severity, the mechanism of anti-Jra-induced HDFN remains to be elucidated.

Characteristics of Bilirubin According to the Results of the Direct Antiglobulin Test and Its Impact in Hemolytic Disease of the Newborn.

BACKGROUND: Hyperbilirubinemia, which is a sign of hemolytic disease of the newborn (HDN), can irreversibly damage the central nervous system. OBJECTIVES: To determine the etiology of HDN in affected patients and characterize the changing pattern of bilirubin using direct antiglobulin testing (DAT). METHODS: We collected clinical data from newborns who underwent perinatal DAT and from their mothers, between August 2008 and July 2017. RESULTS: Among 303 neonates, 37 (12.2%) showed positive DAT results. The positive predictive values (PPVs) and negative predictive values (NPVs) based on DAT results were 75.7% and 28.9%, respectively, for starting phototherapy. Bilirubin levels increased more rapidly in the DAT-positive group, compared with the DAT-negative group. The initial bilirubin level differed significantly according to the etiology of hyperbilirubinemia. Further, neonates with anti-D showed higher delta bilirubin per day than neonates with other antibodies. CONCLUSION: Our results may help to determine the measurement period for bilirubin according to DAT results and etiology.

Severe ABO Hemolytic Disease of the Newborn Requiring Exchange Transfusion.

ABO incompatibility (ABOi), the most common cause of hemolytic disease of the newborn (HDN), is nearly always mild and treatable with phototherapy. Reports of ABOi HDN requiring neonatal exchange transfusion are extremely rare since the inception of modern guidelines. Here, a case of ABOi HDN clearly met criteria for exchange transfusion. An O-positive African American mother delivered a B-positive neonate that quickly developed hyperbilirubinemia. The neonatal DAT was positive from anti-B and anti-A,B, and maternal IgG titer was 1024. Double volume exchange transfusion resulted in a favorable outcome. Given early discharge of newborns, further understanding of factors predicting severe disease is needed.

Jk3 alloantibodies during pregnancy-blood bank management and hemolytic disease of the fetus and newborn risk.

BACKGROUND: The Kidd-null phenotype, Jk(a-b-), occurs in individuals who do not express the JK glycoprotein. Jk(a-b-) individuals can make an antibody against the Jk3 antigen, a high-incidence antigen present in more than 99.9% of most populations. This presents many challenges to the blood bank including identification of the antibody, masking of other antibodies, and how to provide transfusion support given the rarity of Jk3-negative blood products. Kidd antibodies may cause acute and delayed hemolytic reactions as well as hemolytic disease of the fetus and newborn (HDFN). In this article, we present a series of four practical cases of pregnant women with the anti-Jk3 alloantibody that demonstrate a range of clinical presentations of Kidd-related HDFN. STUDY DESIGN AND METHODS: We retrospectively reviewed the clinical and blood bank records for four patients and their newborns encountered at institutions in Tennessee, Missouri, Hawaii, and Guam with an anti-Jk3 identified during pregnancy. RESULTS: Two cases showed no significant evidence for HDFN, while two cases were of mild-to-moderate severity requiring early delivery due to elevated middle cerebral artery (MCA) flow velocities but requiring only phototherapy for hyperbilirubinemia. No intrauterine or neonatal transfusions were necessary. Anti-Jk3 alloantibody titers ranged from 2 to 128. CONCLUSION: Clinical manifestations of anti-Jk3 HDFN are generally mild to moderate. Anti-Jk3 titers were not found to correlate directly with HDFN severity. We suggest a titer of 16 to 32 as a cutoff for implementing enhanced monitoring of fetal MCA flow velocities, as such titers may be indicative of elevated HDFN risk.

The incidence and outcome of clinically significant antibodies detected in Rhesus-D positive pregnant women of the Northern Territory.

BACKGROUND: Haemolytic disease of the fetus/newborn secondary to clinically significant non-Rhesus-D antibodies has risen in importance since the advent of immunoprophylactic anti-D administration to Rhesus-D negative women. Of interest is the incidence of these antibodies in Rhesus-D positive women, who receive less frequent antenatal alloantibody screening. This is of particular concern if the antibodies arise late in pregnancy and may go undetected. AIMS: To assess the proportion of Rhesus-D positive pregnant women with late developing clinically significant antibodies for haemolytic disease of the fetus/newborn, and whether these resulted in adverse fetal outcomes. MATERIALS AND METHODS: A retrospective analysis over a 12-month period at a tertiary hospital in the Northern Territory. Group and antibody screen results in addition to clinical data regarding pregnancy/newborn were collected. RESULTS: Sixty-four of 2612 women (2.5%) had red blood cell antibodies detected during their pregnancy. Of these, 21 clinically significant antibodies were detected in 19 women (0.7% of initial cohort). The most common antibody detected was anti-c (28.5%). In six of these women (0.23% of initial cohort), the antibodies were late developing. Mild jaundice was noted in three newborns with phototherapy required in one. CONCLUSIONS: Although clinically significant antibodies were detected during pregnancy, and in a small proportion of cases as a late developing antibody undetected in the first trimester screening, clinical outcomes for the newborn were mild. As such, the cost of retesting all Rhesus-D positive pregnant women in the third trimester would be considerable and unlikely to result in any meaningful clinical benefit.

Anti-M induced severe haemolytic disease of foetus and newborn in a Malay woman with recurrent pregnancy loss.

Haemolytic disease of the foetus and newborn (HDFN) is caused by maternal red blood cells (RBC) alloimmunisation resulted from incompatibility of maternal and foetal RBCs. However, only a few HDFN attributed to anti-M were reported, varying from asymptomatic to severe anaemia with hydrops foetalis and even intrauterine death. A case of severe HDFN due to anti-M alloantibody from an alloimmunized grandmultiparous Malay woman with recurrent pregnancy loss is reported here. The newborn was delivered with severe and prolonged anaemia which required frequent RBC transfusions, intensive phototherapy and intravenous immunoglobulin administration. Although anti-M is rarely known to cause severe HDFN, a careful serological work-up and close assessment of foetal well-being is important, similar to the management of RhD HDFN. Alloimmunisation with anti-M type can lead to severe HDFN and even foetal loss.

[Positive Coomb's test in newborns; causes and clinical consequences Summary of cases diagnosed in the Blood Bank in the years 2005 to 2012].

INTRODUCTION: Hemolytic disease of the fetus and newborn (HDFN) is caused by the destruction of fetal red blood cells due to red cell antibodies produced by the mother. HDFN can cause fetal hydrops during pregnancy or neonatal jaundice after birth. Direct Antiglobulin Test (DAT) detects antibodies bound to red cells and is a valuable test aiding in the diagnosis of HDFN. In Iceland DAT is routinely performed on cord blood or newborn blood samples if the mother is Rhesus D negative or has non-A/B red cell alloantibodies. The aim of this study was to investigate the causes and consequences of positive DAT in newborns in Iceland over a period of eight years. MATERIAL AND METHODS: The study population was infants diagnosed with a positive DAT in the Blood Bank in Iceland in the years 2005-2012. Relevant data on the blood group and antibody status of mother and child, blood transfusion and DAT results were retrieved from the Blood Bank information system ProSang. Birth records provided information on birth weight, gestational age and phototherapy. Health records from the Children's Hospital provided information on the management and fate of the newborn. RESULTS: Over the study period 383 newborns had a positive DAT result at the Blood Bank. In 73.6% of cases the underlying cause was ABO blood group mismatch between mother and infant, in 20.4% of cases the mother had non-A/B red cell alloantibodies, in 3.9% both of above factors were present, while in 2.1% the cause was unclear. A total of 179 (47.6%) children had neonatal jaundice that required treatment, of which 167 (93.3%) only needed phototherapy. Eight infants required exchange transfusion, five of these had Rhesus antibodies and three ABO blood group mismatch. CONCLUSION: ABO blood group mismatch between mother and child was the most common cause for a positive DAT in neonates in Iceland in the years 2005-2012. Almost half of the neonates required treatment but usually phototherapy was sufficient. Rarely, blood transfusion or exchange transfusion was necessary in severe cases of ABO blood group mismatch or non-A/B red cell alloantibodies. KEY WORDS: Coombs test, Direct Antiglobulin Test (DAT), Hemolytic disease of the fetus and newborn (HDFN), ABO blood group mismatch, red cell alloantibodies, neonatal jaundice, exchange transfusion. Correspondence: Anna Margret Halldorsdottir, annamha@landspitali.is.

Third trimester screening for alloimmunisation in Rhc-negative pregnant women: evaluation of the Dutch national screening programme.

OBJECTIVE: To evaluate the effect of red blood cell (RBC) antibody screening in the 27th week of pregnancy in Rhc-negative women, on detection of alloimmunisation, undetected at first trimester screening ('late' alloimmunisation), and subsequent haemolytic disease of the fetus and newborn (HDFN), to assess risk factors for late alloimmunisation. DESIGN: Prospective cohort and nested case-control study. SETTING: The Netherlands. POPULATION: Two-year nationwide cohort. METHODS: Prospective inclusion of Rhc-negative women with negative first trimester screening and of screen-negative controls. Assessment of incidence and numbers needed to screen (NNS) of late alloimmunisation and HDFN; logistic regression analysis to establish risk factors for late alloimmunisation. MAIN OUTCOME MEASURES: Late alloimmunisation, HDFN. RESULTS: Late alloimmunisation occurred in 99 of 62 096 (0.159%) Rhc-negative women; 90% had c/E antibodies and 10% non-Rhesus antibodies. Severe HDFN (fetal/neonatal transfusion) occurred in two of 62 096 (0.003%) of Rhc-negative women and 2% of late alloimmunisations; moderate HDFN (phototherapy) occurred in 20 children [22.5%; 95% confidence interval (CI), 13.8-31.1%]. Perinatal survival was 100%. The NNS to detect one HDFN case was 2823 (31 048 for severe, 3105 for moderate HDFN). Significant risk factors were former blood transfusion [odds ratio (OR), 10.4; 95% CI, 1.14-94.9], parity (P-1: OR, 11.8; 95% CI, 3.00-46.5; P > 1: OR, 7.77; 95% CI, 1.70-35.4) and amniocentesis/chorionic villus sampling during current pregnancy (OR, 9.20; 95% CI, 1.16-72.9). CONCLUSIONS: Additional screening of Rhc-negative women improved the detection of late alloimmunisation and HDFN, facilitating timely treatment, with a NNS of 2823. Independent risk factors for late alloimmunisation were blood transfusion, parity and chorionic villus sampling/amniocentesis in the current pregnancy. The occurrence of most factors before the current pregnancy suggests a secondary immune response explaining most late alloimmunisations. TWEETABLE ABSTRACT: Third trimester screening for alloimmunisation in Rhc-neg women improves detection and treatment of severe HDFN.