Rhesus D alloimmunization in pregnancy from 1996 to 2015 in Iceland: a nation-wide population study prior to routine antenatal anti-D prophylaxis.

BACKGROUND: Rhesus D (RhD) incompatibility is still the most important cause of hemolytic disease of the fetus and newborn (HDFN) worldwide. The aim of this study was to investigate the incidence, causes, and consequences of anti-D alloimmunizations in pregnancy in Iceland, prior to implementation of targeted routine antenatal anti-D prophylaxis (RAADP) in 2018. STUDY DESIGN AND METHODS: This was a nation-wide cohort study of 130 pregnancies affected by RhD alloimmunization in Iceland in the period from 1996 through 2015. Data were collected from transfusion medicine databases, medical records, and the Icelandic Medical Birth Register. RESULTS: Of 130 RhD alloimmunizations, 80 cases (61.5%) represented new RhD immunization in the current pregnancy. Sensitization was discovered in the third trimester in 41 (51.3%) and occurred in the first pregnancy in 14 cases (17.5%). The most likely causative immunization event was the index pregnancy for 45 (56.25%), a previous pregnancy/birth for 26 (32.5%), abortion for 3 (3.75%), and unknown for 6 women (7.5%). Higher anti-D titers were associated with shorter gestational length, cesarean sections, positive direct antiglobulin test (DAT), and severe HDFN. Intrauterine transfusion (IUT) was performed in five pregnancies (3.8%), and 35 of 132 (26.5%) live-born neonates received treatment for HDFN; 32 received phototherapy (24.2%), 13 exchange transfusion (9.8%), and seven simple blood transfusion (5.3%). CONCLUSION: In about half of cases, RhD alloimmunization was caused by the index pregnancy and discovered in the third trimester. Thus, the newly implemented RAADP protocol should be effective in reducing the incidence of RhD immunization in Iceland in the future.

Anti-D quantification in relation to anti-D titre, middle cerebral artery Doppler measurement and clinical outcome in RhD-immunized pregnancies.

BACKGROUND: The optimal strategy to monitor RhD-immunized pregnancies is not evident. Whether a quantitative analysis of anti-D antibodies adds valuable information to anti-D titre is unclear. The aim of this study was to evaluate the relevance of anti-D quantification in routine monitoring of RhD-immunized pregnancies. MATERIALS AND METHODS: In a retrospective study, 64 consecutive pregnancies in 61 immunized women with anti-D titre ≥128 at any time during pregnancy were included. According to routine, at titre ≥128, anti-D quantification was performed by flow cytometry and the peak systolic velocity in the middle cerebral artery was measured by ultrasound. Decisions for treatment with intrauterine blood transfusion were based on increased peak systolic velocity in the middle cerebral artery. RESULTS: Increasing anti-D concentrations correlated well to increasing anti-D titres, but at each titre value, there was a large interindividual variation, in the determined anti-D concentration. Intrauterine transfusions were initiated in 35 pregnancies according to algorithms based on ultrasound measurements, at anti-D concentrations of 2·4-619 IU/ml and titre 128-16 000. Sixty pregnancies resulted in a live-born child, three in miscarriage and one in termination of pregnancy. During the perinatal care in the neonatal intensive care unit, thirty-one of the neonates were treated with blood exchange transfusions and/or red cell transfusions and 47 were treated with phototherapy. CONCLUSION: Anti-D quantification does not add further information compared to anti-D titre, in defining a critical level to start monitoring RhD-immunized pregnancies with Doppler ultrasound.

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.

Red blood cell alloimmunization in pregnancy during the years 1996-2015 in Iceland: a nation-wide population study.

BACKGROUND: Red blood cell (RBC) alloimmunization during pregnancy is still a major problem. Historically, anti-D antibodies are most likely to cause severe hemolysis, but other antibodies are also important. In Iceland, postnatal RhIg prophylaxis was implemented in 1969, universal RBC antibody screening was implemented in 1978, but antenatal RhIg prophylaxis is not yet routine. STUDY DESIGN AND METHODS: This nation-wide population study gathered data on alloimmunized pregnancies in Iceland between 1996 and 2015. Blood bank alloimmunization data were linked to Icelandic Medical Birth Registry data. RBC antibodies were classified as either clinically significant or clinically nonsignificant. RESULTS: In total, 912 positive antibody screens from 87,437 births were identified (1.04% prevalence). The most frequent antibodies were anti-M (19.4%), anti-E (19.0%), and anti-D (12.5%). Anti-D prevalence among D-negative mothers was 1.1%. Icelandic Medical Birth Registry data were available for 881 (96.6%) pregnancies. In the clinically significant group (n = 474), anti-E (27%) and anti-D (20%) were most common, whereas anti-M was most frequent (53%) in the clinically nonsignificant group (n = 407). Mothers in the clinically significant group were older, more often multigravidae, had more abortions and stillbirths, and had shorter gestational length. Newborns in the clinically significant group were less healthy, had lower weight and Apgar scores, and required more treatment. Among specificities in the clinically significant group, anti-D antibodies were most strongly associated with severe hemolysis. CONCLUSION: In this study, the prevalence of alloimmunization was similar to that in previous reports. Of all clinically significant antibodies, anti-D was most strongly associated with severe hemolysis, requiring phototherapy or exchange transfusions. Our data emphasize the importance of implementing an antenatal prophylactic RhIg program in Iceland in the near future.

Targeted antenatal anti-D prophylaxis program for RhD-negative pregnant women - outcome of the first two years of a national program in Finland.

INTRODUCTION: The aim of this study was to assess the accuracy of the non-invasive fetal RHD test at 24-26 weeks of gestation as part of the national antenatal screening program to target routine antenatal anti-D prophylaxis (RAADP) at 28-30 weeks at women carrying an RhD-positive fetus. MATERIAL AND METHODS: A prospective cohort study involving all maternity care centers and delivery hospitals in Finland between February 2014 and January 2016. Fetal RHD genotyping using cell-free fetal DNA in maternal plasma was performed with real-time polymerase chain reaction in a centralized setting. The results were systematically compared with the serological newborn RhD typing. The main outcome measure was the accuracy of the fetal RHD assay; the secondary variable was compliance with the newly introduced RAADP program. RESULTS: Fetal RHD was screened from 10 814 women. For the detection of fetal RHD, sensitivity was 99.99% [95% confidence interval (CI) 99.92-99.99] and specificity 99.81% (95% CI 99.60-99.92). One false-negative and seven false-positive results were reported by the delivery hospitals in two years. The negative predictive value of the test was 99.97% (95% CI 99.81-99.99). At the end of the study period, over 98% of the RhD-negative women participated in the new screening program. CONCLUSIONS: The targeted RAAPD program was implemented effectively in the national maternity care program in Finland. An accurate fetal RHD screening test allows discontinuation of newborn testing without risking the postnatal prophylaxis program. In the future, the main area to investigate will be the clinical effect of RAADP on subsequent pregnancies.

Prevalence of positive direct antiglobulin test and clinical outcomes in Surinamese newborns from D-negative women.

BACKGROUND: In low-resource countries, screening for D antibodies to detect pregnancies at risk for hemolytic disease of the newborn is not routine practice. Retrospective data showed that 5.5% of Surinamese newborns of D-negative women had a positive direct antiglobulin test (DAT), indicating the presence of maternal antibodies against fetal antigens. Here, the frequency and clinical relevance of DAT positivity is evaluated. STUDY DESIGN AND METHODS: Between April 2015 and June 2016, an observational, multicenter cohort study was undertaken among Surinamese newborns born to D-negative women. In newborns, the DAT was performed, and clinical outcomes between DAT-negative and DAT-positive newborns were compared. RESULTS: Of the 232 evaluable newborns, 19 (8.2%) had a positive DAT, of which 11 of 15 antibody-tested newborns had D antibodies. DAT-positive newborns had lower hemoglobin levels (p = 0.02) and a trend toward higher bilirubin concentrations (p = 0.09) in the first days of life compared with DAT-negative newborns. DAT-positive newborns were admitted more frequently (p = 0.02), needed phototherapy treatment almost four times as often as DAT-negative newborns (26% vs. 7%; p = 0.008), and therapy took 2 days longer (p = 0.01). Exchange transfusions were performed in two newborns with D antibodies, both complicated with sepsis. The hospital stay was 2.5 days longer for DAT-positive newborns (p = 0.007). Overall, the prevalence of hemolytic disease of the newborn requiring treatment was 2.2% among the whole cohort of newborns. CONCLUSION: We found a high prevalence of DAT positivity with substantial need for hyperbilirubinemia treatment in newborns in Suriname. These results stress the necessity for better management procedures in D-negative women.

Successful treatment of severe rhesus D-incompatible pregnancy with repeated double-filtration plasmapheresis.

Fetal anemia is caused by Rhesus (RhD) sensitization as a result of RhD incompatibility during pregnancy. The severe form of this disease can cause hydrops fetalis leading to intrauterine death. We experienced a highly sensitized 39-year-old woman with B Rh-negative blood. She had a history of three induced abortions and experienced perinatal death associated with hydrops fetalis. During the pregnancy prior to her most recent one, she was treated with double-filtration plasmapheresis (DFPP), high dose γ-globulin and intrauterine fetal blood transfusion (IUT). For her most recent pregnancy, we performed only weekly or fortnightly DFPP from 13 weeks until delivery. Anti-D antibody titer was maintained between 32 and 256 without any signs of fetal anemia. IUT was not required at any stage of the pregnancy. No adverse events were observed. She successfully delivered a healthy male infant weighing 2,289 g by Cesarean section at 35 weeks. Repeated DFPP may be an effective and safe strategy to reduce antibody titers in highly sensitized women with RhD-incompatible pregnancy, avoiding the need for IUT.

A case of severe Rh (D) alloimmunization treated by intensive plasma exchange and high-dose intravenous immunoglobulin.

BACKGROUND: In extremely severe Rh (D) alloimmunization, during pregnancy, early diagnosis and treatment is essential to avoid hydrops fetalis. Intrauterine transfusion (IUT) is of utmost importance in the prevention of fetal anemia but it is usually feasible only after 20 weeks of pregnancy. Therefore, additional treatment options in early pregnancy are needed. STUDY DESIGN AND METHODS: A 27-year-old severely D+C immunized woman was admitted at 8 weeks of gestation in her fifth pregnancy with an extremely high concentration of anti-D. Her first pregnancy was uneventful but resulted in D+C alloimmunization. The next two pregnancies were unsuccessful, because of hydrops fetalis resulting in fetal death in pregnancy week 20 and 24, respectively, despite treatment with high-dose intravenous immunoglobulin (IVIG) and IUT treatment. A fourth pregnancy was terminated with legal abortion. The patient was eager and persistent to accomplish a successful pregnancy. Therefore, a combination of treatments consisting of plasma exchange (PE) three times/week and IVIG 100g/week was started in pregnancy week 12. PE was performed 53 times and totally 159L of plasma was exchanged. RESULTS: The anti-D concentration was 12mug/mL (IAT titer 2000) before start of treatment by PE and IVIG in pregnancy week 12. The concentration of anti-D was gradually reduced to approximately 3mug/mL after only two weeks of treatment and was maintained at that level until pregnancy week 22. In pregnancy week 26 and 27, signs of hydrops were detected by ultrasonography and IUT were performed at each occasion. Sectio was inevitable at pregnancy week 28+1 and a male baby was born: Hb 58g/L (cord sample) and 68g/L (venous sample); weight 1385g; Apgar score=4-5-7; Bilirubin 56-150mmol/L (4h). Exchange transfusion was performed on day two and day five. Phototherapy was also implemented for eight days. The newborn's recovery thereafter was uneventful and complete. CONCLUSION: A combination of PE and IVIG may be an efficient treatment possible to start in early pregnancy in patients with extremely severe Rh (D) alloimmunization, with a history of hydrops fetalis in previous pregnancies.

Hemolytic disease of the newborn due to anti-Di: a case study and review of the literature.

BACKGROUND: The severity of hemolytic disease of the newborn (HDN) due to Diego(b) (Di(b)) mismatch ranges from no symptoms to severe jaundice that requires exchange transfusion (ET). The clinical significance of anti-Di(b) is incompletely recognized. CASE REPORT: A male newborn, referred with jaundice, was revealed to have HDN due to Di(b) mismatch and was treated successfully with phototherapy and high-dose intravenous gamma globulin (IVGG). STUDY DESIGN AND METHODS: The literature of HDN caused by Di(b) mismatch was reviewed. The cases were classified into three groups according to their severity: the mildest needed no therapy (NO), the moderate group received phototherapy alone (PHOTO), and the most severe was treated with ET and/or high-dose IVGG therapy plus phototherapy (ET/IVGG). RESULTS: Among 27 cases of HDN due to Di(b) reported to date, 10, 6, and 11 cases required NO, PHOTO, and ET/IVGG, respectively. A significant correlation (p < 0.01) was found between the maternal anti-Di(b) titer and the severity of the disease when the ET/IVGG group was compared with the NO group. All mothers of the group that needed ET/IVGG had an anti-Di(b) titer of 64 or greater. CONCLUSION: A maternal high titer (> or =64) of anti-Di(b) is associated with a higher risk of severe hyperbilirubinemia for mismatched newborns.

Review of the problems involved in using enzymes in blood group serology--provision of freeze-dried ICSH/ISBT protease enzyme and anti-D reference standards. International Council for Standardization in Haematology. International Society of Blood Transfusion.

Proteolytic enzyme preparations and techniques used routinely in blood group serology for the detection of atypical patient antibodies prior to transfusion vary widely and are often poorly standardised. Recent advances have been made in the use of biochemical methods to standardise and stabilise the potency of the enzyme preparations used. A joint working party of the International Council for Standardization in Haematology (ICSH) and the International Society of Blood Transfusion (ISBT) has investigated possibilities for the provision of standards for the protease preparations and techniques. The specification for these standards was that the performance of enzyme reference preparation in the reference technique should be of equivalent sensitivity to the ICSH/ISBT LISS spin indirect antiglobulin test using a titration series of a reference weak anti-D, and be free from false-positive reactions. The working party circulated materials for evaluation in inter-laboratory trials, followed by a laboratory workshop meeting to achieve agreement on the specification for reference materials and methods. Reference freeze-dried papain at 0.6 azoalbumin units and weak anti-D preparations (91/562) have been prepared and validated to meet these specifications. The performance of a test enzyme preparation in the technique for which it is recommended for use should be at least equal to that of the reference papain preparation, by the reference two-stage technique in terms of sensitivity, using a titration series of the reference anti-D, and freedom from false-positive reactions, using six fresh inert sera. The reference papain and weak anti-D can also be used to calibrate the level of proteolytic activity required in other procedures in blood group serology, such as new technology methods for antibody detection, and automated and microplate cell grouping procedures. These preparations and an agreed method for their use are now available from listed centres as ICSH/ISBT and Food and Drug Administration reference materials.