Prediction of ABO hemolytic disease of the newborn using pre- and perinatal quantification of maternal anti-A/anti-B IgG titer.

BACKGROUND: Hemolysis in fetus/newborns is often caused by maternal antibodies. There are currently no established screening procedures for maternal ABO antibodies harmful to fetus/newborn. We investigated the clinical significance, and predictive value of maternal anti-A/B titer for hyperbilirubinemia in ABO-incompatible newborns. METHODS: We conducted a case-control study of blood group O mothers and their ABO-compatible (O) vs. -incompatible (A/B) newborns receiving phototherapy, and of ABO-incompatible newborns receiving phototherapy vs. no phototherapy. Newborn data and treatment modalities were recorded, and total serum bilirubin and hemoglobin were measured. Maternal anti-A/B immunoglobulin-γ (IgG) titers were measured prenatally and perinatally, and negative and positive predictive values (NPV, PPV) were calculated to assess the risk of developing hyperbilirubinemia requiring phototherapy. RESULTS: We found a significantly higher maternal IgG antibody titer in the case group (p < 0.001). Maternal anti-A/B titers at first trimester had modest predictive values: NPV = 0.82 and PPV = 0.65 for neonatal hyperbilirubinemia; titers at birth improved the predictive values: NPV = 0.93 and PPV = 0.73. Newborn hemoglobin was significantly lower in incompatibles compared to compatibles (p = 0.034). Furthermore, increased anti-A/B IgG production during pregnancy was associated with hyperbilirubinemia and hemolysis in incompatible newborns. CONCLUSIONS: There was a significant association between maternal anti-A/B IgG titer and hyperbilirubinemia requiring treatment. IMPACT: Maternal anti-A/B IgG titer in the first trimester and at birth is predictive of hemolytic disease of the ABO-incompatible newborn. Increased IgG anti-A/B production throughout pregnancy in mothers to ABO-incompatible newborns developing hyperbilirubinemia contrasts a constant or reduced production in mothers to newborns not developing hyperbilirubinemia. Screening tools available in most immunohematology laboratories can identify clinically important IgG anti-A/B. Use of maternal samples taken at birth yielded NPV = 0.93 and PPV = 0.73.

Hemolytic anemia caused by non-D minor blood incompatibilities in a newborn.

Hyperbilirubinemia is one of the most widely seen cause of neonatal morbidity. Besides ABO and Rh isoimmunization, minor blood incompatibilities have been also been identified as the other causes of severe newborn jaundice. We report a newborn with indirect hyperbilirubinemia caused by minor blood group incompatibilities (P1, M, N, s and Duffy) whose hemolysis was successfully managed with intravenous immunoglobulin therapy. A thirty-two gestational weeks of preterm male baby became severely icteric on postnatal day 11, with a total bilirubin level of 14.66 mg/dl. Antibody screening tests revealed incompatibility on different minor groups (P1, M, N, s and Duffy (Fya ve Fyb)). On postnatal day thirteen, the level of bilirubin increased to 20.66 mg/dl although baby was under intensive phototherapy. After the administration of intravenous immunoglobulin and red blood cell transfusion, hemoglobin and total bilirubin levels became stabilised. Minor blood incompatibilities should be kept in mind during differential diagnosis of hemolytic anemia of the newborn. They share the same treatment algorithm with the other types hemolytic anemia. New studies revealed that intravenous immunoglobulin treatment in hemolytic anemia have some attractive and glamorous results. It should be seriously taken into consideration for treatment of minor blood incompatibilities.

Is Cord Blood Bilirubin Level a Reliable Predictor for Developing Significant Hyperbilirubinemia?

OBJECTIVE: We aimed to investigate whether cord blood bilirubin (CBB) level could be used to identify the newborns at a high risk of developing hyperbilirubinemia. STUDY DESIGN: Total and direct serum bilirubin level were evaluated from umbilical cord blood of newborns. We checked blood groups and Rh status of all mothers and determined blood groups and direct Coombs test (DC) of newborns born to mothers whose blood group was O type or Rh negative to determine the maternal-fetal blood group or Rh incompatibility. RESULTS: A total of 418 newborns were included, and phototherapy (PT) was required in 17 newborns. The cutoff value of CBB for predicting the occurrence of significant hyperbilirubinemia requiring PT was 1.67 mg/dL, with a sensitivity of 82% and specificity of 99%. The mean CBB level in babies receiving PT was 2.4 ± 0.9 mg/dL. When blood group, CBB level, DC, gender, and mode of delivery were assigned as possible risk factors, multivariate analysis showed ABO, Rh incompatibility, and CBB level increased the risk of PT requirement. CONCLUSION: CBB could be useful to determine newborns at a risk of developing hyperbilirubinemia and prevent developing severe complications due to delay in diagnosis.

Indirect neonatal hyperbilirubinemia in hospitalized neonates on the Thai-Myanmar border: a review of neonatal medical records from 2009 to 2014.

BACKGROUND: Indirect neonatal hyperbilirubinemia (INH) is a common neonatal disorder worldwide which can remain benign if prompt management is available. However there is a higher morbidity and mortality risk in settings with limited access to diagnosis and care. The manuscript describes the characteristics of neonates with INH, the burden of severe INH and identifies factors associated with severity in a resource-constrained setting. METHODS: We conducted a retrospective evaluation of anonymized records of neonates hospitalized on the Thai-Myanmar border. INH was defined according to the National Institute for Health and Care Excellence guidelines as 'moderate' if at least one serum bilirubin (SBR) value exceeded the phototherapy threshold and as 'severe' if above the exchange transfusion threshold. RESULTS: Out of 2980 records reviewed, 1580 (53%) had INH within the first 14 days of life. INH was moderate in 87% (1368/1580) and severe in 13% (212/1580). From 2009 to 2011, the proportion of severe INH decreased from 37 to 15% and the mortality dropped from 10% (8/82) to 2% (7/449) coinciding with the implementation of standardized guidelines and light-emitting diode (LED) phototherapy. Severe INH was associated with: prematurity (< 32 weeks, Adjusted Odds Ratio (AOR) 3.3; 95% CI 1.6-6.6 and 32 to 37 weeks, AOR 2.2; 95% CI 1.6-3.1), Glucose-6-phosphate dehydrogenase deficiency (G6PD) (AOR 2.3; 95% CI 1.6-3.3), potential ABO incompatibility (AOR 1.5; 95% CI 1.0-2.2) and late presentation (AOR 1.8; 95% CI 1.3-2.6). The risk of developing severe INH and INH-related mortality significantly increased with each additional risk factor. CONCLUSION: INH is an important cause of neonatal hospitalization on the Thai-Myanmar border. Risk factors for severity were similar to previous reports from Asia. Implementing standardized guidelines and appropriate treatment was successful in reducing mortality and severity. Accessing to basic neonatal care including SBR testing, LED phototherapy and G6PD screening can contribute to improve neonatal outcomes.

In utero treatment of severe fetal anemia resulting from fetomaternal red blood cell incompatibility: a comparison of simple transfusion and exchange transfusion.

OBJECTIVE: To compare in utero exchange transfusions (IUET) and in utero simple transfusions (IUST) for the treatment of fetal anemia resulting from red blood cell fetomaternal incompatibility. STUDY DESIGN: Retrospective comparative study from January 2006 through December 2011. The two techniques were compared for effectiveness, complications, and neonatal outcomes. RESULTS: 36 patients had 87 IUETs and 85 patients 241 IUSTs. Gestational age at the first transfusion was similar in both groups (IUET: 27±3.8 weeks; IUST: 27±4.7 weeks; NS) as was the initial fetal hemoglobin level (IUET: 6.4±2.8g/dL; IUST: 6.0±2.5g/dL; NS). No significant differences were noted for postprocedure complications or efficacy. The daily drop in hemoglobin level was similar in both groups (IUET: 0.41±0.23g/dL/day; IUST: 0.44±0.17g/dL/day; NS) as were the time intervals between two procedures. Gestational age at birth was earlier in the IUET group (34.4±1.3 weeks vs 35.5±1.8 weeks; p<0.001), but the postnatal transfusions or exchange transfusions rates and the duration of intensive phototherapy did not differ. No significant differences were noted for the overall survival rates (IUET: 100%; IUST: 96.4%; p>0.99). CONCLUSION: IUET does not appear to provide any benefits compared with IUST, neither to be associated with a higher complication rate. The choice of the technique depends on availability of packed blood cells with high hematocrit (70-80%).

Indication of Mild Hemolytic Reaction Among Preterm Infants With ABO Incompatibility.

BACKGROUND: Among term infants, ABO incompatibility is a leading cause of hemolytic disease and neonatal jaundice. With respect to preterm infants, data are lacking. OBJECTIVE: To evaluate the incidence and severity of ABO incompatibility hemolytic disease among preterm infants with respect to hemolytic and jaundice parameters. DESIGN: Clinical and laboratory data were collected retrospectively from the medical records of 118 ABO-incompatible preterms born at gestational age (GA) 29-34 weeks, as well as 118 controls matched for GA, birth weight, and multiplicity. All infants were born at the Sheba Medical Center Tel-Hashomer between 2009 and 2012. RESULTS: The study and control groups were similar on all maternal and neonatal outcome parameters. No differences between the groups were recorded throughout hospitalization regarding hematocrit levels or the need for blood transfusion. Bilirubin levels were higher among the study (ABO-incompatible) group during the first 10 days of life; however, no significant differences were found regarding the need for phototherapy. Upon evaluating subgroups divided by GA, we found no differences on any hematological and jaundice factors among preterms of 29-31 weeks, whereas among preterms of 32-34 weeks higher positive direct antiglobulin test (DAT) results (7% vs. 0% in the control, P = 0.014) as well as higher bilirubin levels were documented. CONCLUSIONS: Among ABO-incompatible preterm infants with GA 29-34 weeks, there is no evidence of significant hemolytic reaction derived from placental transfer of antibodies. With increasing GA, antibody transfer becomes more significant, resulting in more positive DAT results and greater incidence of neonatal jaundice.

Variable Clinical Presentations of ABO Incompatibility in Dizygotic Twins.

Newborns with ABO blood group incompatibility can have a spectrum of clinical presentations from remaining asymptomatic to severe hemolytic anemia with jaundice. This case presentation discusses dizygotic twins who demonstrated both ends of the clinical spectrum. Similar cases in which there is such extreme variation between twins were not attainable in the current literature, which prompted the authors to present it as a rare occurrence and one that was unexpected based on their past experience with ABO incompatibility both in singletons and in twins.

[Efficacy and safety of intravenous immunoglobulins in the management of neonatal hyperbilirubinemia due to ABO incompatibility: a meta-analysis]. / Efficacité et tolérance des immunoglobulines polyvalentes dans l'hyperbilirubinémie néonatale par incompatibilité ABO. Méta-analyse.

OBJECTIVES: ABO fetomaternal red blood cell incompatibility (ABO FMI) induces an immune hemolysis after fetal transfer of hemolyzing maternal anti-A or anti-B. ABO hemolytic disease (ABO HD) remains the most frequent cause of severe and early jaundice in newborns. High levels of unconjugated hyperbilirubinemia may induce acute and chronic neurological complications. Severe hyperbilirubinemia can be prevented by first-line phototherapy (PT) treatment, but exchange transfusion (ET) is required if treatment is not effective, even if ET is linked with high hemodynamic, infectious, gastrointestinal, and/or biological morbidity. Intravenous human polyclonal immunoglobulins (IVIg) have been proposed in concomitant use with PT in order to avoid the requirement for ET in ABO FMI. METHODS: Electronic databases of all published clinical trials in neonatal hyperbilirubinemia due to ABO incompatibility were systematically queried for randomized controlled clinical trials comparing PT alone to PT associated with IVIg based on the requirement for ET. Duration of PT and adverse events were optional criteria. A meta-analysis of the selected data was performed on six selected trials out of 28 found. RESULTS: IVIg doses ranged from 0.5 to 1.5 g/Kg in one to three administrations. Requirement for ET was lower in the IgIV+PT group, with a relative risk of 0.27 [CI 95% 0.17-0.42; P<0.00001], expressed as a number needed to treat of five neonates to avoid one ET. The mean duration of PT was 4 days in the PT group and association of PT with IVIg significantly reduced the duration of PT treatment by 0.84 days. The tolerance of the IVIg and PT association was good with no reported cases of ulcerative enterocolitis in 265 treated newborns. CONCLUSION: IVIG associated with PT reduces the need for ET and the duration of PT in newborns with hyperbilirubinemia due to ABO hemolytic disease. Their efficacy and good tolerance prompt consideration of IVIg as a therapeutic adjuvant to PT in severe hemolytic hyperbilirubinemia due to ABO incompatibility.

Activity of therapeutic JAK 1/2 blockade in graft-versus-host disease.

Graft-versus-host-disease (GVHD) is a severe complication of allogeneic hematopoietic cell transplantation (allo-HCT) characterized by the production of high levels of proinflammatory cytokines. Activated Janus kinases (JAKs) are required for T-effector cell responses in different inflammatory diseases, and their blockade could potently reduce acute GVHD. We observed that inhibition of JAK1/2 signaling resulted in reduced proliferation of effector T cells and suppression of proinflammatory cytokine production in response to alloantigen in mice. In vivo JAK 1/2 inhibition improved survival of mice developing acute GVHD and reduced histopathological GVHD grading, serum levels of proinflammatory cytokines, and expansion of alloreactive luc-transgenic T cells. Mechanistically, we could show that ruxolitinib impaired differentiation of CD4(+) T cells into IFN-γ- and IL17A-producing cells, and that both T-cell phenotypes are linked to GVHD. Conversely, ruxolitinib treatment in allo-HCT recipients increased FoxP3(+) regulatory T cells, which are linked to immunologic tolerance. Based on these results, we treated 6 patients with steroid-refractory GVHD with ruxolitinib. All patients responded with respect to clinical GVHD symptoms and serum levels of proinflammatory cytokines. In summary, ruxolitinib represents a novel targeted approach in GVHD by suppression of proinflammatory signaling that mediates tissue damage and by promotion of tolerogenic Treg cells.

UGT1A1 gene variants and clinical risk factors modulate hyperbilirubinemia risk in newborns.

OBJECTIVE: To study the contribution of UGT1A1 gene variants and clinical risk factors in modulating hyperbilirubinemia risk in newborns. STUDY DESIGN: Seven UGT1A1 gene variants and clinical risk factors were studied in 113 hyperbilirubinemia cases and 218 control newborns. Hyperbilirubinemia was defined as the total serum bilirubin levels >95th percentile of the American Academy of Pediatrics nomogram. The study population included term (37 to 41 weeks) newborns below 2 weeks of age. RESULT: UGT1A1 gene variants, namely, c.211G>A, g.-3279T>G, TATA box polymorphism and CAT insertion were identified as independent molecular risk factors for neonatal hyperbilirubinemia, whereas c.686C>A, c.1091C>T and c.1456T>G were not detected in study cohort. Among clinical risk factors, excessive weight loss, sepsis and ABO incompatibility emerged as independent risk factors. Co-expression of UGT1A1 variants and clinical risk factors further accentuated the risk of neonatal hyperbilirubinemia. CONCLUSION: Multiple risk factors, whether genetic or clinical, are instrumental in modulating hyperbilirubinemia risk in newborns. Disordered bilirubin conjugation through interactions of UG1TA1 gene variants contributes to the clinical phenotype of neonatal hyperbilirubinemia.

Neonatal hyperbilirubinemia due to ABO incompatibility: does blood group matter?

Newborn infants with maternal-fetal ABO incompatibility are at a greater risk for developing subsequent significant hyperbilirubinemia, and therefore, prediction of probable risk factors, such as the degree of hemolysis, gains importance. In this study, we aimed to evaluate the effect of fetal-neonatal blood group on the severity of hemolysis and jaundice due to maternal-fetal ABO incompatibility. In a retrospective analysis of 166 cases with ABO hemolytic disease of the newborn, risk factors for the severity of jaundice were compared in infants with blood group A or B. Both groups had similar demographic parameters such as birth weight, gender and day of admission. Similarly, there were no statistically significant differences in hematological parameters, such as initial hemoglobin levels, initial and final indirect bilirubin levels, frequency of positive direct Coombs test and hemolytic findings on peripheral blood smear, duration of phototherapy, number of exchange transfusions, and intravenous immunoglobulin (IVIG) therapy (p>0.05). We conclude that blood type has no effect on the severity of the hemolytic jaundice in ABO incompatibility.

Morbidity of ABO haemolytic disease in the newborn.

BACKGROUND: Better understanding of the clinical characteristics of ABO haemolytic disease in neonates helps optimise care. OBJECTIVE: To assess the morbidity associated with maternal-neonatal ABO incompatibility. METHODS: Neonates with blood groups A or B born to mothers with blood group O with simultaneous rhesus blood factor compatibility were studied prospectively. Maternal and neonatal details, direct Coomb's test (DCT) on the cord blood, onset and progression of jaundice, and requirement and duration of phototherapy were studied. Neonates requiring phototherapy were considered to have significant hyperbilirubinaemia, and peripheral smear, reticulocyte count and haematocrit values were obtained. ABO haemolytic disease of the newborn (ABO HDN) is defined as a newborn with a positive DCT and/or laboratory evidence of haemolysis such as reticulocytosis and spherocytes on blood smear. RESULTS: Of 878 deliveries, 151 (17.3%) neonates were ABO incompatible with their mothers. The proportions who were O-A and O-B incompatible were 50.4% and 49.6%, respectively. Forty-six (30.4%) had significant hyperbilirubinaemia (119.7-256.5 mmol/L) and required phototherapy, 26 (34.2%) of them in the O-A group and 20 (26.6%) in the O-B group. None required exchange transfusion. Jaundice was detected within the first 24 hours in 47.8%. Of 46 newborns who required phototherapy, 25 (54.3%) had laboratory evidence of haemolysis. DCT was positive in 1.9% of ABO-incompatible newborns. There was no significant difference in the incidence and severity of haemolysis between the O-A and O-B-incompatible neonates. Neonates with haemolysis required phototherapy significantly earlier and for longer than neonates without haemolysis (P<0.001). CONCLUSIONS: ABO incompatibility was observed in 17.3% of pregnancies with almost equal O-A and O-B frequency. About a third of infants had significant hyperbilirubinaemia. There was no difference in severity between those with O-A and O-B HDN.

Hyperbilirubinemia: current guidelines and emerging therapies.

It is estimated that about two thirds of newborns will appear clinically jaundiced during their first weeks of life. As newborns and their mothers spend fewer days in the hospital after birth, the number of infants readmitted yearly in the United States for neonatal jaundice over the last 10 years has increased by 160%. A portion of these infants present to the emergency department, requiring a careful history and physical examination assessing them for the risk factors associated with pathologic bilirubin levels. Although the spectrum of illness may be great, the overwhelming etiology of neonatal jaundice presenting to an emergency department is physiologic and not due to infection or isoimmunization. Therefore, a little more than a good history, physical examination, and indirect/direct bilirubin levels are needed to evaluate an otherwise well-appearing jaundiced newborn. The American Academy of Pediatrics' 2004 clinical practice guidelines for "Management of Hyperbilirubinemia in the Newborn Infant 35 or More Weeks of Gestation" are a helpful and easily accessible resource when evaluating jaundiced newborns (available at http://aappolicy.aappublications.org/cgi/content/full/pediatrics;114/1/297). There are several exciting developments on the horizon for the diagnosis and management of hyperbilirubinemia including increasing use of transcutaneous bilirubin measuring devices and medications such as tin mesoporphyrin and intravenous immunoglobulin that may decrease the need for exchange transfusions.

Middle cerebral artery-peak systolic velocity in dizygotic twins with anti-E alloimmunization.

Middle cerebral artery-peak systolic velocity (MCA-PSV) has been reported to predict fetal anemia with similar accuracy as amniotic ΔOD450 assay. Alloimmunized dizygotic twin pregnancy allows us to compare anemic and non-anemic twins in the same intrauterine environment. We herein present a case of Rh (E)-incompatible dizygotic twin pregnancy, where MCA-PSV could precisely detect the anemia in one of the twins. A 36-year-old woman, whose previous child required exchange transfusion due to hemolytic anemia of newborn (HFDN), conceived twins after in vitro fertilization-embryo transfer. At 24 weeks' gestation, MCA-PSV of twin A and twin B were 23.9 cm/s (0.8 multiples of median; MoM) and 30.7 cm/s (1.0 MoM), respectively. At 31 weeks' gestation, MCA-PSV values of both twins were sharply elevated to nearly 1.4 MoM. Thereafter, MCA-PSV of twin A fell to 1.0 MoM, whereas MCA-PSV of twin B exceeded 1.5 MoM at 34 weeks' gestation. Development of fetal anemia was suspected and emergency cesarean section was performed. Twin B showed moderate anemia with positive direct Coombs' test and was diagnosed as HFDN due to anti-E alloimmunization. Twin B required phototherapy and red cell transfusion, but exchange transfusion was safely obviated.

Extreme hyperbilirubinemia in newborn infants.

This study was undertaken to determine the frequency and investigate the etiology of extreme hyperbilirubinemia (total serum bilirubin [TSB]>or=25 mg/dL [428 micromol/L]) in newborns admitted to a neonatal intensive care unit in southern Turkey. The charts of 93 term and near-term infants admitted with TSB levels of 25 mg/dL (428 micromol/L) or greater in the first 30 days after birth were retrospectively reviewed. During the 4.5-year study period, 774 infants were admitted to our unit with neonatal jaundice. Ninety-three (12%) of these infants had TSB levels of 25 mg/dL (428 micromol/L) or greater. The mean TSB level in the 93 cases was 30.1+/-5.7 mg/dL (514.7+/-97.5 micromol/L), and the peak levels ranged from 25.0 to 57.4 mg/dL (428-981.5 micromol/L). Thirty-three (35.5%) of the 93 babies had TSB levels of 30 mg/dL (513 micromol/L) or greater. Eighty-nine of 93 infants were being exclusively breast-fed. Nineteen babies were isoimmunized, 7 were bacteremic, 2 of the 39 babies tested for glucose-6-phosphate dehydrogenase had this enzyme deficiency, and 1 of the 71 infants tested for thyroid function had hypothyroidism. No cause for extreme hyperbilirubinemia was found in 61 (65.6%) cases.

Intravenous immunoglobulin in the management of hemolytic disease of the newborn.

Jaundice caused by hemolysis continues to challenge practitioners caring for infants in the NICU. Bilirubin levels can rise quickly in the first days of life, and interventions must be prompt to prevent side effects related to hyperbilirubinemia. Conventional treatments such as hydration and phototherapy are common, but new studies suggest that use of intravenous immunoglobin (IVIG) as an additional treatment may prevent the need for exchange transfusion in some babies. This article presents a case study of an infant with blood-type incompatibility treated successfully with multiple doses of IVIG, discusses the pathophysiology and clinical presentation of hemolytic jaundice, and reviews current management strategies for this disease.

[The practice guideline 'Blood transfusion' (third integral revision)]. / Richtlijn 'Bloedtransfusie' (3e algehele herziening).

The revised and expanded practice guideline 'Blood transfusion' describes the whole transfusion chain within the hospital for the first time. Despite compatibility tests before transfusion (determination of the ABO and Rhesus blood groups and detection of clinically relevant antibodies (C, c, D, E, e, Fy(a), Fy(b), Jk(a), Jk(b), M, S and s)), transfusion reactions can occur. So that a transfusion reaction can be recognised in time, the patient must be observed intensively for the first 5-10 minutes after the start of any new transfusion and the vital functions must be recorded. In patients with a Hb level of 4-6 mmol/l, the decision whether or not to transfuse should be made dependent on the patient's other characteristics. Thrombocyte transfusion is not indicated in case of thrombopenia due to increased breakdown or pooling. If leukaemia, tumour infiltration or drug toxicity is the underlying cause of thrombopenia, then a platelet count of 10 x 10(9)/l or 20 x 10(9)/l should be the transfusion trigger. Reduction of the number of blood transfusions can be achieved by the administration of epoetin in case of renal insufficiency: transfusion can thus be avoided in more than 70% of the patients concerned. Autotransfusion during surgery with severe blood loss also results in a reduction of the number of allogenic blood transfusions.

Does prophylactic phototherapy prevent hyperbilirubinemia in neonates with ABO incompatibility and positive Coombs' test?

OBJECTIVE: The objective of the study was to determine whether initiation of early phototherapy in positive direct Coombs' test (DCT) with ABO-incompatible newborns would prevent severe jaundice. STUDY DESIGN: A prospective controlled study was performed at Al Qassimi Hospital. Infants born at term and weighing >2000 g with ABO incompatibility and a positive DCT were included in the study. Within their first 4 hours of life and after parental consent, infants were enrolled into one of two groups: prophylactic phototherapy group, which received phototherapy during the first 24 hours of life (group I), or no prophylactic phototherapy, which represents the control group (group II). Selection of infants to either group was by 2-week alternative strategy. Blood group, complete blood count (CBC), reticulocyte count, blood smears, total serum bilirubin (TSB) and DCT were performed on cord blood of all neonates born to mothers with O-positive blood group. CBC, reticulocytes and TSB level were obtained in all enrolled infants at 12, 24, 48, 72, and 96 hours of life. RESULTS: During the study period, 242 newborns with positive DCT were enrolled. A total of 102 infants were allocated to the prophylactic phototherapy arm and 140 as controls. Prophylactic phototherapy was associated with a significant decrease in the TSB at 24 hours (p=0.002) and at 48 hours (p=0.003) but not later on. The total number of patients who had hyperbilirubinemia at any time during the first 96 hours was significantly less in the prophylactic group (17 vs 45--p=0.006). Prolonged hospital stay because of phototherapy was more frequent in the control group (p=0.03). CONCLUSION: Prophylactic phototherapy was associated with a significant reduction of TSB in the first 48 hours of life but not later on. Clinical benefits of this strategy could not be proven.