Intrauterine Blood Transfusion Research Articles

Prenatal Management and Perinatal Outcome in a Large Series of Hydrops Fetalis.

Nonimmune hydrops fetalis (NIHF) is the most frequent etiology of hydrops fetalis (HF), accounting for around 95% of cases. It associates high perinatal mortality and morbidity rates. The aim of the study was, first, to investigate etiology, prenatal management, and perinatal outcome in a large single-center series of HF; second, to identify prenatal prognostic factors with impact on perinatal outcome. Observational retrospective study of 80 HF diagnosed or referred to a single tertiary center between 2012 and 2021. Clinical characteristics, etiology, prenatal management, and perinatal outcome were recorded. Adverse perinatal outcome was defined as intrauterine fetal death (IUFD), early neonatal death (first 7 days of life) and late neonatal death (between 7 and 28 days). Seventy-six of the 80 cases (95%) were NIHF, main etiology being genetic disorders (28/76; 36.8%). A total of 26 women (32.5%) opted for termination of pregnancy, all of them in the NIHF group. IUFD occurred in 24 of 54 patients (44.4%) who decided to continue the pregnancy. Intrauterine treatment was performed in 29 cases (53.7%). There were 30 newborns (55.6%). Adverse perinatal outcome rate was 53.7% (29/54), significantly higher in those diagnosed <20 weeks of gestation (82.4% < 20 weeks vs. 40.5% ≥ 20 weeks; p = 0.004). Survival rate was higher when fetal therapy was performed compared to the expectantly managed group (58.6% vs. 32%; p = 0.05). Intrauterine blood transfusion and thoraco-amniotic shunt were the procedures that achieved the highest survival rates (88.9% and 100%, respectively, p = 0.003). NIHF represented 95% of HF with genetic disorders as the main etiology. Most of them were diagnosed before 20 weeks of gestation, with worse prognosis than cases detected later in gestation. Rates of TOP, IUFD, and early neonatal death were higher in NIHF. Intrauterine therapy, when indicated, improved the perinatal outcome.

539 Clinical characteristics and outcomes of intrauterine blood transfusion (IUT) for infectious etiologies

539 Clinical characteristics and outcomes of intrauterine blood transfusion (IUT) for infectious etiologies

SFM Fetal Therapy Practice Guidelines: Intrauterine Blood Transfusion

AbstractDespite routine antenatal anti-D prophylaxis with immunoglobulin, Rh alloimmunization and hemolytic disease of the fetus and newborn continue to occur due to a myriad of reasons. Intrauterine intravascular transfusion (IUT) or fetal blood transfusion is a therapeutic prenatal procedure in which specifically prepared and treated unit of donor red blood cells is injected intravascularly into the umbilical vein under ultrasound guidance. Originally introduced in the year 1963, it continues to be the standard treatment for severe fetal anemia. The objective of this guideline is to provide an evidence-based update of IUT for the perinatal healthcare providers.

Case of Hemolytic Disease of the Fetus and Newborn Treated Without Blood Products.

Hemolytic disease of the fetus and newborn (HDFN) affects 3/100,000 to 80/100,000 patients yearly and can cause severe anemia and hyperbilirubinemia. Recombinant human erythropoietin has been used as an adjunct therapy in patients with HDFN and hypo-regenerative anemia in the setting of receiving intrauterine blood transfusions. This case describes a patient with HDFN, in which the family were Jehovah Witnesses, and blood transfusions were declined. The patient had symptomatic anemia with a hematocrit nadir of 18.6%. The patient was successfully treated with recombinant human erythropoietin, ferrous sulfate, and folic acid, avoiding the need for transfusion.

Current Insights Into K-associated Fetal Anemia and Potential Treatment Strategies for Sensitized Pregnancies

K-associated anemic disease of the fetus and newborn (K-ADFN) is a rare but life-threatening disease in which maternal alloantibodies cross the placenta and can mediate an immune attack on fetal red blood cells expressing the K antigen. A considerably more common disease, D-associated hemolytic disease of the fetus and newborn (D-HDFN), can be prophylactically treated using polyclonal α-D antibody preparations. Currently, no such prophylactic treatment exists for K-associated fetal anemia, and disease is usually treated with intrauterine blood transfusions. Here we review current understanding of the biology of K-associated fetal anemia, how the maternal immune system is sensitized to fetal red blood cells, and what is understood about potential mechanisms of prophylactic HDFN interventions. Given the apparent challenges associated with preventing alloimmunization, we highlight novel strategies for treating sensitized mothers to prevent fetal anemia that may hold promise not only for K-mediated disease, but also for other pathogenic alloantibody responses.

THE RISK OF PERINATAL LOSSES DUE TO PARVOVIRUS INFECTION DURING PREGNANCY AND WAYS TO PREVENT THEM

THE RISK OF PERINATAL LOSSES DUE TO PARVOVIRUS INFECTION DURING PREGNANCY AND WAYS TO PREVENT THEM

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.

Clinical Efficacy and Nursing Care of Fetal Intrauterine Blood Transfusion: Previous Experience Review

To summarize the clinical efficacy and nursing experience of intrauterine blood transfusion (IUT) treatment for fetal anemia cases. The clinical data of 4 fetal anemia cases receiving IUT in Beijing Obstetrics and Gynecology Hospital, Capital Medical University between 2020 and 2022 were collected. Four pregnant women aged 24-38 years were included in the study. They carried fetuses with anemia of unknown causes. The four pregnant women developed anxiety after they were informed of the diagnosis of fetal anemia. One-on-one psychological counseling before the IUT procedure and one-on-one companionship over the course of the surgery were provided for the pregnant women. In addition, they were closely monitored for blood transfusion reactions. Postprocedural observation of the puncture site and 24-hour monitoring of the newborns were also conducted. The four pregnant women underwent 1-3 times of IUT in the second and third trimesters, with the minimum gestational age at the time of IUT being 25 + weeks and the blood transfusion volume being 20-107 mL/time. Two pregnant women experienced irregular uterine contractions during IUT in the third trimester. Other than that, all other IUT treatments were successful. After IUT, there was a significant improvement in fetal hemoglobin, peak systolic velocity of the middle cerebral artery (MCA-PSV), and cardiothoracic area ratio. One case did not give birth in our hospital and the outcome of the fetus was not known. The other three fetuses achieved good outcomes. Positive preprocedural psychological counseling for pregnant women, close intraoprocedural and postprocedural pregnancy monitoring, and the prevention of maternal and fetal complications are the key to improving the clinical efficacy of IUT and achieving a good fetal outcome.

Rhesus alloimmunization is correlated to necrotizing enterocolitis and respiratory distress: A tertiary center experience

Background Rh alloimmunization occurs in pregnant women who do not express the red blood cell Rh antigen phenotype but carry a fetus that does. The mainstay of treatment is intrauterine blood transfusion (IUT). Necrotizing enterocolitis (NEC) is a rapidly progressive and life-threatening emergency that most commonly affects preterm neonates. It has been noticed that NEC has a predilection toward neonates with rhesus hemolytic disease (RHD) compared to neonates without RHD, particularly among the late preterm to near-term population with a moderate to severe grade of RHD. Methodology This is a retrospective cohort study that included all neonates delivered in our hospital between January 2015 and December 2021,who received IUT due to Rh-isoimmunization, and the control group consisted of neonates, who did not have Rh-isoimmunization and no history of IUT. Neonates were excluded from the study if they met our exclusion criteria. Results During a 7-year study period, a total of 144 neonates were included in the study. Of those, 72 neonates had RHD and received IUT (group 1), while 72 neonates did not have RH isoimmunization and did not receive IUT (group 2). Maternal and neonatal demographic data were similar between the two groups, except for birth weight, which was higher in group 1 (2.49 vs. 2.31 kg, P = 0.025). Ten cases developed NEC (13.89%) in group 1, while there were no cases of NEC in the other group (P = 0.001). We also found that the initial hemoglobin level was lower in group 1 (135.4 vs. 174.3 g/dL) with a P value of <0.001. The duration of respiratory support was significantly higher in group 1 (2.27 vs. 0.319 days; P = 0.006). Neonatal sepsis was more in group 1 (19.44 vs. 1.39%; P = 0.002). There was no significant difference between the two groups in terms of respiratory distress syndrome, intraventricular hemorrhage, and retinopathy of prematurity. Conclusion Neonates with rheus hemolytic disease (RHD) who undergo IUT are at a higher risk of developing NEC and prolonged course of respiratory support. Extra cautions may be necessary when advancing feeding in these patients. A well-designed multicenter prospective trial with an adequate sample size is recommended to validate our result.

Intrauterine Blood Transfusion for Parvo B19-Induced Fetal Anemia: Neuroimaging Findings and Long-Term Neurological Outcomes

Introduction: We aimed to evaluate the neuroimaging findings and long-term neurodevelopmental outcomes of fetuses and children following intrauterine blood transfusion (IUT) for parvo B19 infection-induced anemia compared to those with RBC alloimmunization. Methods: We conducted a retrospective cohort study including women who underwent an IUT due to fetal anemia between 2006 and 2019 in a tertiary, university-affiliated medical center. The cohort was divided into two groups: a study group – fetuses affected by congenital parvo B19 infection; and a control group – fetuses affected by RBC alloimmunization. Retrospective data such as antenatal sonographic evaluations, fetal brain MRI results, and short-term fetal and neonatal outcomes were collected. All children underwent a neurodevelopmental evaluation after birth using a Vineland questionnaire. Primary outcome was defined as the presence or absence of neurodevelopmental delay. Secondary outcome was defined as the presence of abnormal fetal neuroimaging findings such as cerebellar hypoplasia, polymicrogyria, intracranial hemorrhage, or severe ventriculomegaly. Results: Overall, 71 fetuses requiring at least one IUT were included in the study. Of these, 18 were affected by parvo B19 infection and 53 by RBC alloimmunization with various associated antibodies. Fetuses in the parvo B19 group presented at an earlier gestational age (22.91 ± 3.36 weeks vs. 27.37 ± 4.67 weeks, p = 0.002) and were more affected by hydrops (93.33% vs. 16.98%, p < 0.001). Three fetuses out of the 18 (16.67%) fetuses in the parvo B19 group died in utero following the IUT. Abnormal neuroimaging findings were detected in 4/15 (26.7%) of the parvo B19 survivors versus 2/53 (3.8%) of fetuses affected by RBC alloimmunization (p = 0.005). There was no difference in long-term neurodevelopmental delay rates between the children in the study and control groups, as assessed at the average age of 3.65 and 6.53 years, accordingly. Conclusion: Fetal anemia due to parvo B19, treated with IUT, might be associated with increased rates of abnormal neurosonographic findings. The correlation between those findings and long-term adverse neurodevelopmental outcomes requires further investigation.

Double/Triple Intrauterine Blood Transfusion in Rh-isoimmunized Anemic Fetuses in Multiple Pregnancies with Favorable Outcome.

Multiple pregnancies have increased with the use of assisted reproduction, and we expect more women reporting with Rh isoimmunization among multiple gestation in near future. Intrauterine transfusion in singleton itself is technically difficult and requires a lot of skill and precision. Performing double/triple transfusion in twins/triplets is expected to be more demanding. To create awareness on the technical difficulties encountered in intrauterine transfusion in twins and triplets. We report a case series of four Rh-isoimmunized twins/triplets in 5years who presented with severe anemia requiring intrauterine transfusion. Each of the four sets of cases had their own intricacies that needed to be pondered before tackling them as not much was available in the literature. In Case 1, the first twin intrauterine transfusion in our 20-year-long experience, the difficulty in the approach to the first twin due to a posteriorly placed placenta has been highlighted. Case 2 was rare due to the concomitant presence of atypical antibodies in the mother in addition to Rh-D isoimmunization that made it difficult to cross match any donor blood for intrauterine transfusion. The third case was exclusive due to its monochorionic-diamniotic nature of the twins where the impact of inter-twin anastomosis on the transfusion was to be taken into consideration. Fourth case was a triplet gestation where the difficulty of which cord to be assigned to which fetus, the crowded space for intervention, as well as the risk of prolonged operative time and associated risk of preterm/premature rupture of membranes were our concern. Intrauterine transfusion (IUT) in twins/triplets is challenging. Difficulties encountered during IUT in multifetal gestation are due to different or uncertain chorionicity, intraplacental anastomosis between vessels, different degree of anemia in twins, difficult to ascertain cord-fetus relationship and difficulty to reach placental insertion site due to crowding by multiple fetal parts.

The Perinatal Outcomes of Maltese and Sub-Saharan African Migrant Women: A Comparative, Retrospective Study

A paucity of evidence exists on whether the health and social services introduced in Malta for Sub-Saharan African (SSA) migrants have improved perinatal outcomes.Research Aim:This research aimed to compare the sociobiological characteristics and obstetric and perinatal outcomes between SSA migrant women and a local cohort of Maltese women who delivered neonates in Malta.Design:A retrospective comparison of two samples, SSA migrant women and Maltese women utilized the national obstetrics database kept by the Medical and Health Department during 2007–2016. The database had information about 898 SSA mothers (914 neonates) and 36,083 Maltese mothers (36,736 neonates). Statistical comparison was carried out using Pearson’s chi-square test.Results:SSA migrants were significantly more likely to be younger, married, poorly educated, and less likely to smoke cigarettes or abuse illicit drugs. They were statistically more likely to be multiparous and to poorly avail themselves of available antenatal care. Although SSA migrants had a significantly increased risk for perinatal complications, including preeclampsia–eclampsia, threatened preterm labor, placental abruption, intrauterine growth restriction, anemia, infection, hemorrhage, and blood transfusions, the risk for perineal trauma was lower than that for Maltese women. Significantly increased complications in SSA neonates included prematurity, low birth weight, low Apgar scores, respiratory distress syndrome, sepsis, seizures, and increased mortality.Conclusion:Despite the availability of comprehensive free-at-source obstetric healthcare and social support services, the perinatal outcomes of SSA migrants remained substandard when compared to Maltese women. These findings require further investigation of the adequacy and standard of maternity care offered to SSA migrants.

Suspected twin anemia polycythemia sequence in a dichorionic, diamniotic twin pregnancy: a case report

BackgroundTwin anemia polycythemia sequence is a rare complication in monochorionic twin pregnancy.Case presentationWe describe a case of dichorionic twin pregnancy presenting with suspected twin anemia polycythemia sequence. A 31-year-old White female, on her third pregnancy, had a routine ultrasound scan at 12 weeks gestation, which demonstrated a dichorionic twin pregnancy with one placenta located in the anterior wall and the other in the posterior wall of the uterus. At 21 weeks, a scan demonstrated a 24% growth discordance between the two fetuses with normal Doppler studies and amniotic fluid. At 27 weeks, one twin showed signs of anemia and the other polycythemia; the fetal middle cerebral artery peak systolic velocity was high in the anemic fetus and low in the polycythemic twin (1.8 and 0.5 multiples of the median). An intrauterine blood transfusion was carried out and this increased the fetal hemoglobin concentration in the anemic twin from 3.5 to 12.5 g/dL. At 29 weeks, delivery by cesarean section was carried out because of evidence from middle cerebral artery peak systolic velocity of recurrence of anemia in one twin and worsening polycythemia in the co-twin; at birth the hemoglobin concentrations were 5.6 and 24.9 g/dL, respectively. Histopathological examination confirmed dichorionicity with no communicating vessels between the two placentas.ConclusionsThis is the first case of twin anemia polycythemia sequence in a dichorionic, diamniotic twin pregnancy where intrauterine blood transfusion was used to prolong the pregnancy by almost 2 weeks in a “twin anemia polycythemia sequence-like” setting.

A CASE OF INCOMPATIBILITY DUE TO MATERNAL ANTI-C

Hemolytic disease of the fetus and newborn (HDN) is a condition in which the lifespan of an infant's red blood cells (RBCs) is shortened by the action of specific IgG antibody (ies) derived from the mother directed against Rhesus or other blood group antigens on fetal RBCs that are inherited from the father but are not expressed by the mother. The widespread use of Rh immune globulin has dramatically decreased the occurrence of anti D-HDN among D negative pregnant women, but has not eliminated the problem. No measures are available to prevent sensitization to other blood groups, most notably other Rhesus (C,c,E,e), Kell and Duffy antigens. In this article, a case of anti-c incompatibility is presented and the issue of risks involving Rh negative blood transfusion in aloimmunized patients with anti-c is discussed. Twin live babies named newborn1, sex female, and newborn2 were born from the 8th pregnancy of a 38 year-old brazilian mother from Pinhão-Paraná-Brazil through a normal vaginal route. Medical report of newborn1 during twenty days described levels of indirect bilirubin oscillating between 7 to 11 mg/dl and hemoglobin dropping from 13,9 to 10,1 g/dl without jaundice, phototherapy or transfusion registered. Thirty days postnatal, newborn1 had hemoglobin 7,7 g/dl and indirect bilirubin 11,3mg/dl and a blood transfusion was required. Antibody screen of the mother was positive and crossmatching with O negative blood was not compatible. Other tests, performed at Hemocentro Regional de Guarapuava-Paraná, identified mother's blood as A positive, phenotype C(+)c(-)E(-)e(+)K1(-), antibody screen detected anti-c antibodies with 1:256 titre. Baby's blood sample was identified as O positive, phenotype C(+)c(+)E(-)e(+)K1(-) with the direct anti-globulin test (DAT) positive (2+). After centrifugation with saline solution baby's sample after showed yellowed supernatant. A blood transfusion with 30 ml of O positive, c antigen negative blood, match compatible with the mother's serum, was transfused without reactions. At the hospital the mother revealed that these were her 8th and 9th children. Also, she said to be illiterate and that ignored her pregnancy until the 8th month and for it she simply did not have antenatal care. Unfortunately details about her other pregnancies could not be got. Anti-c is an important Rh antibody that may cause severe HDN, and in some cases may be as severe as anti-D HDN. In a series of 1022 cases of non Rh D aloimmunization Kenneth found that only anti-c was associated with severe HDN that ended in hydropic stillbirth or necessitated intrauterine blood transfusion[1]. This was not the case presented in the article. Nevertheless, an important aspect embedded issue along with anti-c that goes unnoticed by many refers to the matter of Rh negative blood available for transfusion, including aloimmunized anti-c patients. The stereotype held by Rh negative blood as universal blood not applies to anti-c. If ones take into account the high incidence of c antigen both in Rh positive and Rh negative blood among the population, we can suppose that people having anti c antibodies, like the mother in the article, are sitted on an authentic powder keg where a transfusional mistake, either for misinformation or any reason can bring unexpected results.

Intrauterine transfusion of a hydropic fetus with anemia due to a giant chorioangioma: A case report

Giant chorioangiomas are a potentially life-threatening condition that may require intrauterine therapy. We describe a case of a large chorioangioma (>4cm) diagnosed at 30 weeks of gestation causing severe fetal anemia and hydrops. An intrauterine blood transfusion was performed at 31 weeks with reversal of the anemia and hydrops. The neonate was born at 37 weeks showing respiratory distress syndrome that required neonatal intensive care unit admission but was discharged at 30 days of life. Further evaluation at two months of age showed no signs of abnormal neurodevelopment. When timely indicated, intrauterine transfusion of a hydropic fetus with anemia due to a giant chorioangioma is a potentially life-saving therapy that shows good neurodevelopment of the surviving fetus.

Development of a Training Model for Teaching Intrauterine Fetal Blood Transfusion

This article describes an inexpensive simulator developed for teaching intrauterine blood transfusion. The model is constructed from a boneless chicken thigh folded over a Penrose drain placed in a water-filled snap-lock lid container and covered by melted ballistic gel to simulate the fetal intrahepatic vessel. Participants valued this educational tool and reported feeling the model was practical and realistic. This low-cost, high-fidelity model provides realistic tissue resistance and represents a sonographically accurate intrahepatic fetal blood transfusion training tool.

MANAGEMENT OF FETAL ANEMIA AND THROMBOCYTOPENIA WITH INTRAUTERINE BLOOD TRANSFUSION

Fetal anemia and fetal thrombocytopenia are two of the most unsmiling complications in pregnant women, and they can lead to perinatal mortality and morbidity. After long years of study with intravascular intrauterine blood transfusion, a number of varieties of implications have been described. Intrauterine Blood Transfusion (IUBT) is considered the best method in the case of fetal anemia because it is caused by red cell alloimmunization. Not only for red blood cell transfusion, this method can also be used for the transfusion of platelets to thrombocytopenic fetuses in pregnant women. It is generally detected after a child is born who is symptomatic and shows signs of bleeding in the brain and skin. The biggest milestone for the clinician is to give preventive treatment in next pregnancy. Pregnancies at risk require serial monitoring, and Fetal Middle Cerebral arterial (MCA) Doppler is the non-invasive test that is now proving to be the choice for monitoring. IVIG (Intravenous immunoglobulin) is used to manage severe Rh-immunization and is now showing promising effects. Indications like Parvovirus B19, Fetomaternal hemorrhage (FMH), Fetal SacrococcygealTeratoma (SCT), Twin-twin transfusion syndrome, placental chorioangioma diseases, or other infections can be treated with this method. This review covers fetal transfusion techniques and explores current management of fetal anemia and thrombocytopenia.

A Nonimmune Hydrops Case.

A Nonimmune Hydrops Case.

Population-based incidence and risk factors for cholestasis in hemolytic disease of the fetus and newborn

ObjectiveTo estimate the incidence of cholestasis in neonates with hemolytic disease of the fetus and newborn (HDFN) and investigate risk factors and long-term liver disease.Study designA population-based cohort study of all infants born with HDFN within the Stockholm region between 2006 and 2015. The study period was the first 90 days of life, and presence of any chronic liver disease was evaluated at two years of age.ResultsCholestasis occurred in 7% (11/149). Median age at detection was 1.1 days. Intrauterine blood transfusions and maternal alloimmunization with multiple red blood cell antibodies including D-, c- or K-antibodies were independent risk factors for cholestasis. No infant had chronic liver disease at two years of age.ConclusionsInfants with severe HDFN have increased risk for cholestasis, particularly those requiring multiple intrauterine transfusions. Early and repeated screening for conjugated hyperbilirubinemia in the first week of life is needed to ensure adequate management.

The rate of decline in fetal hemoglobin following intrauterine blood transfusion in the management of red cell alloimmunization

ObjectiveHemolytic disease of the fetus and newborn is characterized by fetal anemia, secondary to maternal alloantibody-mediated fetal erythrocyte destruction. Despite our reliance on intrauterine blood transfusion (IUT) to maintain severely affected pregnancies, it remains difficult to predict the fetal response to an infusion of donor blood. Our objective was to determine the daily rate of decline in fetal hemoglobin following one, two, and three transfusions. We also evaluated the relationship between the fetal hemoglobin level and the corresponding doppler measurement of the fetal middle cerebral artery peak systolic velocity (MCA-PSV). Study DesignA prospective observational study of all singleton pregnancies treated with intrauterine transfusion for fetal anemia secondary to maternal alloimmunization at the National Maternity Hospital, a tertiary referral centre, was conducted over a 10-year period (2011–2020). Demographic and clinical data was obtained from the electronic patient records. Ethical approval was granted by the Ethics and Research Committee of the National Maternity Hospital. ResultsA total of 90 intrauterine blood transfusions were performed in 41 fetuses affected by maternal alloimmunization, of which 70% (n = 29), 34% (n = 14) and 15% (n = 6) required a 2nd, 3rd, and 4th transfusion, respectively. The mean rate of decline in fetal hemoglobin following the first transfusion was 0.4 g/dl/day (range, 0.12–0.64 g/dl/day). The mean rate of decline was lower after repeat transfusions at 0.27 g/dl/day (range, 0.16–0.45 g/dl/day). The sensitivity of MCA-PSV threshold of 1.5 Multiples of the Median (MoM) to detect moderate-severe anaemia declined with rank of IUT, from 82% after one previous transfusion, to 75% after two or more previous transfusions. No fetal mortality was seen in our series. ConclusionKnowledge of the expected rate of decline in fetal hemoglobin following an IUT aids in the determination of appropriate timing of subsequent transfusions in a fetus affected by red cell alloimmunization. We observed a reducing rate of daily decline in hemoglobin in fetuses requiring successive transfusions. Our findings suggest a reduced accuracy of the MCA-PSV threshold of 1.5 MoM in determining the optimal timing of 2nd, 3rd, and 4th transfusions.