Neonatal thrombocytopenia: new insights into pathogenesis and implications for clinical management

Incidence and Risk Factors of Thrombocytopenia in Neonates Admitted with Surgical Disorders to Neonatal Intensive Care Unit of Tikur Anbessa Specialized Hospital: A One-Year Observational Prospective Cohort Study from a Low-Income Country

BACKGROUND

Thrombocytopenia is one of the most common hematologic disorders affecting neonates admitted to the neonatal intensive care unit. The aim of this study was to determine the incidence and associated risk factors of neonatal thrombocytopenia in neonates admitted with surgical disorders.

METHODS

An observational prospective cohort study was conducted and all neonates admitted to neonatal intensive care unit of Tikur Anbessa Specialized Hospital with surgical disorders were included. Data were collected using a checklist and analyzed by SPSS version 23. Chi square test and independent sample t- test were used to assess the association among different variables.

RESULTS

A total of 210 neonates were included in the study, out of which 56.2% were males. The incidence of thrombocytopenia was 55.8%. Among neonates with thrombocytopenia, 90.9% had late onset thrombocytopenia and half were in the severe range (<50,000/µL). The presence of sepsis (P = 0.000) and atresia (P = 0.000) were found to be significantly associated with the development of thrombocytopenia. The mean non feeding hours were found to be significantly longer for patients with thrombocytopenia (t [199], 5.81, P = 0.000).

CONCLUSION

The incidence of thrombocytopenia is high in our institution. Prevention methods towards neonatal sepsis should be given due emphasis.

Predictive efficacy of procalcitonin, platelets, and white blood cells for sepsis in pediatric patients undergoing cardiac surgeries who are admitted to intensive care units: Single-center experience

Background:

Sepsis is one of the major contributor of morbidity and mortality in pediatric cardiac surgeries.

Aim:

The aim of this study was to compare the predictive efficacy of total leukocyte counts (TC), platelet count (PC), and procalcitonin (PCT) for sepsis in patients undergoing cardiac surgeries who are admitted to the Intensive Care Unit.

Materials and Methods:

This prospective, single-center study included 300 neonates, infants, and pediatric patients who had undergone various open heart surgeries at our center from September 2014 to November 2015.

Results:

Overall, the incidence of sepsis was 14% in pediatric patients undergoing cardiac surgeries. TC of postoperative 48 h were significantly lower (11889.19 ± 5092.86 vs. 14583.22 ± 6562.96; P = 0.004) in septic patients. The low levels of platelets on postoperative 24 h and 72 h were observed in patients with sepsis as compared to patients without sepsis, whereas the levels of PCT at various time intervals (preoperative, postoperative - 24 h, 48 h, and 72 h) had shown no association with sepsis in the study population. Low PC (24 h) was the strongest predictor of sepsis showing an odds ratio of 1.9 (95% confidence interval [CI]: 1.42–3.51; P = 0.001) and area under curve of 0.688 with 95% CI of 0.54–0.83 (P = 0.018).

Conclusion:

We may conclude that in Indian pediatric population platelet levels are highly associated with sepsis as compared to any other hematological parameter. The immediate postoperative level of platelet is the strongest predictor of sepsis and could be effectively used in the clinical settings.

Late-onset Neonatal Sepsis-A 10-year Review From North Queensland, Australia

OBJECTIVE

Late-onset sepsis (LOS) in neonates contributes significantly to both morbidity and mortality. To determine the incidence of LOS, risk factors for disease and the impact on subsequent hospital course, we evaluated a cohort of 6340 neonates admitted to the neonatal intensive care unit and of neonates (3-28 days) admitted from the community between January 2005 and January 2016.

METHODS

This was a retrospective case review of all neonates admitted with suspected LOS who had positive blood culture and/or cerebrospinal fluid cultures, for an organism determined to be a pathogen.

RESULTS

Of 6340 neonates who survived beyond 3 days, 2271 (35.8%) had 1 or more blood cultures collected for suspected LOS. Of these, 146 (6.4%) positive blood cultures were thought to represent true bacteremia. The vast majority of infections (73%) were caused by Gram-positive organisms, with coagulase-negative staphylococci accounting for 39.8% of infections. Late-onset neonatal sepsis occurred predominantly in the 24-28-week age group (75.9%) and in neonates who weighed less than 1000 g (73.6%). The incubation time for positive blood cultures for Gram-negative sepsis was less (13 hours) when compared with Gram-positive sepsis (20 hours). Thrombocytopenia, elevated C-reactive protein and chorioamnionitis were consistently associated with late-onset Gram-negative sepsis (P < 0.05). Eight neonates (6%) died secondary to LOS.

CONCLUSIONS

LOS contributes significantly to mortality and morbidity in neonates and remains a challenge to clinicians. Necessary steps to reduce late-onset neonatal sepsis should be undertaken.

Prognostic significance of early platelet count decline in preterm newborns

OBJECTIVES

Decline of platelets with or without thrombocytopenia is observed in critically ill preterm newborns. Prognostic significance of platelets count in Neonatal Intensive Care Unit focused on outcome after thrombocytopenia. We aimed to estimate the changes in platelets count within the first 7 days of life in preterm newborns and its relation to final outcomes.

METHODS

Retrospectively, the platelets count during the first 7 days of life, and its association with mortality, length of stay among survivors (LOS), and later severe morbidities were determined. Appropriate regression analyses were used to examine possible relations between studied variables.

RESULTS AND DISCUSSION

Platelets drop that did not reach thrombocytopenia level in the first 7 days of life happened in 61.7%. Platelets count drop in the first 7 days of life was a predictor of mortality, LOS, and major morbidities such as intraventricular hemorrhage and necrotizing enterocolitis.

CONCLUSIONS

Platelets count drop within the first 7 days of life independent of thrombocytopenia can be used to predict increased mortality, LOS, and the development of later severe morbidities in critically ill preterm neonates.

Mathematical model of platelet turnover in thrombocytopenic and nonthrombocytopenic preterm neonates

Neonatal thrombocytopenia affects 22-35% of all neonates admitted to neonatal intensive care units. The purpose of this study was to develop a mathematical model for characterizing platelet (PLT) kinetics in thrombocytopenic preterm neonates. Immature PLT fraction (IPF) and PLT counts were measured for up to 35 days after birth in 27 very low birth weight preterm neonates. PLT transfusions were administered to 8 of the 27 (24%) subjects. The final model included a series of four transit compartments to mimic the production and survival of IPF and PLT. Model parameters were estimated using nonlinear mixed effects modeling with the maximum likelihood expectation maximization algorithm. The model adequately captured the diverse phenotypes expressed by individual subject profiles. Typical population survival values for IPF and PLT life spans in nonthrombocytopenic patients were estimated at 0.912 and 10.7 days, respectively. These values were significantly shorter in thrombocytopenic subjects, 0.429 and 2.56 days, respectively. The model was also used to evaluate the influence of growth and laboratory phlebotomy loss on the time course of IPF and PLT counts. Whereas incorporating body weight was essential to correct for expanding blood volume due to growth, phlebotomy loss, a possible covariate, did not significantly influence PLT kinetics. This study provides a platform for identifying potential covariates that influence the interindividual variability in model parameters regulating IPF and PLT kinetics and for evaluating future pharmacological therapies for treating thrombocytopenic neonates.

Incidence of Thrombocytopenia in Idiopathic Hyperbilirubinemic Newborns

Background: Hyperbilirubinemia is the most common reason for admission during the neonatal period and may develop serious complications. Thrombocytopenia is defined as platelet count <150,000/mm3 and has not been conclusively reported as a complication of hyperbilirubinemia in any of the standard paediatric textbooks. The aim of this study was to find the incidence of thrombocytopenia in neonates with idiopathic jaundice and the relationship between hyperbilirubinaemia and platelet count.Methods: This was a descriptive-analytic study accomplished on 878 newborns. After a detailed history, clinical examination and baseline investigations,185 babies with idiopathic hyperbilirubinemia were tested for platelet counts and then categorized in two groups namely group A (n=65) and group B (n=120) showing the presence and absence of thrombocytopenia, respectively. Newborns data were recorded and Statistical analysis was carried out, using SPSS 11.5.Results: The incidence of thrombocytopenia was seen in 65 (12%) newborns admitted due to jaundice. The mean serum bilirubin in group A and B was defined as 19.7 (± 6) and 20.4 (± 5), respectively (P = 0.362).There was no significant difference in Laboratory variables likeTSH, T4, coombs test, reticulocite count, serum sodium and hematocrit values between two groups.Conclusion: This study determines higher rate of thrombocytopenia among idiopathic hyperbilirubinemic neonates (36%) and helps the practitioner to be aware of this association and avoid unnecessary investigations.We did not find a significant correlation between serum bilirubin values and thrombocytopenia.

Low immature platelet fraction suggests decreased megakaryopoiesis in neonates with sepsis or necrotizing enterocolitis

OBJECTIVE

In order to conclude on the megakaryopoietic activity during thrombocytopenia in sepsis or necrotizing enterocolitis (NEC), we analyzed the immature platelet fraction (IPF).

STUDY DESIGN

Serial measurements of platelet counts and IPF in neonates with blood culture-proven late-onset sepsis (n=21) or surgical NEC (n=12) at T0: prior to the diagnosis of sepsis/NEC; T1: at diagnosis; T2: days 3 to 5 after onset; T3: days 8 to 12 after onset.

RESULT

In parallel to declining platelet counts, the median absolute IPF significantly decreased between T0 and T2 in neonates with sepsis or NEC. We found a significant positive correlation between the platelet count and absolute IPF (r=0.71; P<0.001). In patients with low IPF (<2 per nl), the platelet count did not subsequently increase. Neonates with NEC who died exhibited significantly lower IPF compared with survivors (P<0.05).

CONCLUSION

Low absolute IPF values during the course of neonatal sepsis/NEC suggest suppression of megakaryopoietic activity.

Incidence of thrombocytopenia in the neonatal intensive care unit

BACKGROUND

Thrombocytopenia is the commonest haematological abnormality encountered in the neonatal intensive care unit (NICU). The incidence in neonates varies greatly, depending upon the population studied. The aim of the present study was to study the incidence of thrombocytopenia in the neonates admitted to the NICU.

METHOD

The study was carried out in 258 consecutive eligible neonates from August 2007 to August 2009. Neonates were placed in two risk groups for thrombocytopenia, viz. high risk and low risk, depending upon the presentation, maternal history and any antenatal/perinatal events. Platelet counts were done on the first, third and fifth day of admission and thereafter every 72 hours till counts were normal. Low counts were collaborated with a peripheral blood smear.

RESULTS AND CONCLUSION

The overall incidence of thrombocytopenia in the study group was 70% (182/258). The incidence in the high-risk group was 93.7% cases (134/143) and in the low-risk group was 41.7% (48/115). This difference was statistically significant. Factors associated with thrombocytopenia were sepsis, extreme low birth weight, intra-uterine growth restriction, birth asphyxia and pre-eclampsia in mothers. The most common severe bleeding manifestation was pulmonary haemorrhage. The overall mortality in babies with thrombocytopenia was 33% despite > 90% of these cases having received platelet transfusion. Of these pulmonary haemorrhage was the main cause of death in five cases. It is concluded that thrombocytopenia is very common in the NICU and should be actively looked for so that it can be managed appropriately.

Organism-specific platelet response and factors affecting survival in thrombocytopenic very low birth weight babies with sepsis

OBJECTIVE

To study organism-specific platelet response and factors affecting survival in thrombocytopenic very low birth weight (VLBW) babies with sepsis.

STUDY DESIGN

Very low birth weight babies (birth weight <1500 g) admitted to a single level-three intensive care unit from January 2000 to December 2005 were prospectively evaluated for sepsis by rapid screen test, blood counts and blood culture. In thrombocytopenic babies, organism-specific platelet response and its effect on various platelet parameters were evaluated. In addition, morbidity, mortality and factors affecting survival were studied.

RESULT

Sepsis was diagnosed in 230 of 620 (37%) patients. Gram-positive sepsis occurred in 20% (46/230), Gram-negative in 71% (164/230) and fungal in 8.6% (20/230) of patients. Thrombocytopenia was observed in 67% (155/230) of babies. The frequency and duration of thrombocytopenia were more with Gram-negative and fungal infections. The incidence of persistent bacteremia, multiorgan failure and death was more in thrombocytopenic neonates (P<0.01). The incidence of multiorgan failure and death was directly related to the duration of thrombocytopenia. On multiple logistic regression analysis, poor prognostic factors include a high SNAP score at admission, a severe drop in platelet count at onset of sepsis, a low platelet nadir, a prolonged duration of thrombocytopenia, a need for platelet transfusion, less number of days off ventilation and a prolonged stay in the hospital.

CONCLUSION

In thrombocytopenic VLBW babies with sepsis, organism-specific platelet response is seen. In addition, persistent bacteremia, multiorgan failure and death are more in these babies, and survival decreases with the increased severity and duration of thrombocytopenia, with prolonged ventilation and increased need for platelet transfusions.

Neonatal thrombocytopenia

Thrombocytopenia (platelets <150 x 10(9)/L) is one of the most common haematological problems in neonates, particularly those who are preterm and sick. In those preterm neonates with early thrombocytopenia who present within 72 h of birth, the most common cause is reduced platelet production secondary to intrauterine growth restriction and/or maternal hypertension. By contrast, the most common causes of thrombocytopenia arising after the first 72 h of life, both in preterm and term infants, are sepsis and necrotizing enterocolitis. The most important cause of severe thrombocytopenia (platelets <50 x 10(9)/L) is neonatal alloimmune thrombocytopenia (NAIT), as diagnosis can be delayed and death or long-term disability due to intracranial haemorrhage may occur. Platelet transfusion is the mainstay of treatment for severe thrombocytopenia. However, the correlation between thrombocytopenia and bleeding is unclear and no studies have yet shown clinical benefit for platelet transfusion in neonates. Studies to identify optimal platelet transfusion practice for neonatal thrombocytopenia are urgently required.

Thrombocytopenia in the neonate

Thrombocytopenia is one of the commonest haematological problems in neonates, affecting at least 25% of all admissions to neonatal intensive care units (NICUs) [Murray NA, Howarth LJ, McCloy MP et al. Platelet transfusion in the management of severe thrombocytopenia in neonatal intensive care unit patients. Transfus Med 2002;12:35-41; Garcia MG, Duenas E, Sola MC et al. Epidemiologic and outcome studies of patients who received platelet transfusions in the neonatal intensive care unit. J Perinatol 2001;21:415-20; Del Vecchio A, Sola MC, Theriaque DW et al. Platelet transfusions in the neonatal intensive care unit: factors predicting which patients will require multiple transfusions. Transfusion 2001;41:803-8]. Although a long list of disorders associated with neonatal thrombocytopenia can be found in many textbooks, newer classifications based on the timing of onset of thrombocytopenia (early vs. late) are more useful for planning diagnostic investigations and day-to-day management. The mainstay of treatment of neonatal thrombocytopenia remains platelet transfusion although it is important to note that no studies have yet shown clinical benefit of platelet transfusion in this setting. Indeed some reports even suggest that there may be significant adverse effects of platelet transfusion in neonates, including increased mortality, and that the effects of transfusion may differ in different groups of neonates with similar degrees of thrombocytopenia [Bonifacio L, Petrova A, Nanjundaswamy S, Mehta R. Thrombocytopenia related neonatal outcome in preterms. Indian J Pediatr 2007;74:269-74; Kenton AB, Hegemier S, Smith EO et al. Platelet transfusions in infants with necrotizing enterocolitis do not lower mortality but may increase morbidity. J Perinatol 2005;25:173-7]. There is also considerable variation in transfusion practice between different countries and between different neonatal units. Here we review recent progress in understanding the prevalence, causes and pathogenesis of thrombocytopenia in the newborn, the clinical consequences of thrombocytopenia and developments in neonatal platelet transfusion.

Transfusion therapy in critically ill children

Critically ill children in pediatric intensive care units are commonly indicated for blood transfusion due to many reasons. Children are quite different from adults during growth and development, and that should be taken into consideration. It is very difficult to establish a universal transfusion guideline for critically ill children, especially preterm neonates. Treating underlying disease and targeted replacement therapy are the most effective approaches. Red blood cells are the first choice for replacement therapy in decompensated anemic patients. The critical hemoglobin concentration may be higher in critically ill children for many reasons. Whole blood is used only in the following conditions or diseases: (1) exchange transfusion; (2) after cardiopulmonary bypass; (3) extracorporeal membrane oxygenation; (4) massive transfusion, especially in multiple component deficiency. The characteristics of hemorrhagic diseases are so varied that their therapy should depend on the specific needs associated with the underlying disease. In general, platelet transfusion is not needed when a patient has platelet count greater than 10,000/mm3 and is without active bleeding, platelet functional deficiency or other risk factors such as sepsis. Patients with risk factors or age less than 4 months should be taken into special consideration, and the critical thrombocyte level will be raised. Platelet transfusion is not recommended in patients with immune-mediated thrombocytopenia or thrombocytopenia due to acceleration of platelet destruction without active bleeding or life-threatening hemorrhage. There are many kinds of plasma-derived products, and recombinant factors are commonly used for hemorrhagic patients due to coagulation factor deficiency depending on the characteristics of the diseases. The most effective way to correct disseminated intravascular coagulation (DIC) is to treat the underlying disease. Anticoagulant therapy is very important; heparin is the most common agent used for DIC but the results are usually not satisfactory. Antithrombin III, protein C, or recombinant thrombomodulin has been used successfully to treat this condition. For reducing the risk of organism transmission and adverse reactions resulting from blood transfusion, the following measures have been suggested: (1) replacement therapy using products other than blood (e.g., erythropoietin, iron preparation, granulocyte colony-stimulating factor); (2) special component replacement therapy for specific diseases; (3) autotransfusion; (4) subdividing whole packed blood products into smaller volumes to reduce donor exposure; (5) advances in virus-inactivating procedures. To avoid viral transmission, vapor-heated or pasteurized products and genetic recombinant products are recommended. Cytomegalovirus (CMV)-seronegative blood, leukoreduced and/or irradiated blood are recommended for prevention of CMV infection, graft-versus-host-disease and alloimmunization in neonate and immunocompromised patient transfusion. There is no reason to prescribe a plasma product for nutritional supplementation because of the risk of complications. The principle: complications of transfusion must be avoided, the rate of blood exposure should be reduced and the safety of the transfused agents or components should be maintained must always be kept in mind.

Increase in platelet count is not affected by the platelet yield of single donor pheresed platelets

OBJECTIVES

To determine if the rise in platelet count after transfusion in neonates is associated with platelet yield of the pheresed platelet unit.

STUDY DESIGN

Cohort study of infants in a level 3 Neonatal Intensive Care Unit that received single donor platelets (SDP). Platelet rise in infants were compared between 3 groups: underproduction, destruction, and idiopathic. The main outcome variable studied was the rise in platelet count posttransfusion. Statistical analysis included analysis of variance, Pearson correlation, and multivariate linear regression.

RESULTS

The gestational age was 28+/-4.5 weeks. The platelet yield was 4.2+/-0.7 (x10(11)) and resultant platelet rise was 71+/-58.6x1000/mm3. Infants with platelet underproduction (n=30) had a greater rise compared with infants with platelet destruction (n=51) after transfusion (95.3+/-58 vs. 59.6+/-57.5x1000/mm3, P=0.01). After controlling for confounding variables, there was no correlation between the platelet yield and platelet rise, but the etiology of the thrombocytopenia remained associated with increased platelet rise.

CONCLUSIONS

There was no association between platelet yield of SDP and platelet rise. Infants with thrombocytopenia related to platelet underproduction had a greater rise in platelets after transfusion compared with those with platelet destruction, independent of yield or volume of the SDP transfusion.

Diagnosis and treatment of heparin-induced thrombocytopenia in neonates and children

Heparin-induced thrombocytopenia (HIT), a well-known side effect of heparin therapy, occurs with an incidence of 1-2% in certain pediatric patient groups. In affected children, HIT markedly increases the risk of venous and arterial thromboembolism. The use of alternative anticoagulation with danaparoid, lepirudin and argatroban in adults and children has demonstrated to be safe and could reduce morbidity and mortality also in affected pediatric patients. Thus, in children and neonates, an early diagnosis and accurate management is crucial to avoid the deleterious consequences of HIT. This review article will focus on the presentation of HIT in neonates and children. It reviews the pathophysiology of HIT and it summarizes epidemiological data. Finally important diagnostic and therapeutic issues are discussed.

Enteric gram-negative bacilli bloodstream infections: 17 years' experience in a neonatal intensive care unit

OBJECTIVE

To assess the occurrence of enteric gram-negative bacilli (EGNB) bloodstream infections (BSI) in a neonatal intensive care setting during a 17-year period in which a consistent antibiotic treatment program was in place. To document infections, outbreaks, or epidemics, emergence of antibiotic resistance, clinical correlates, and outcomes of the most prevalent EGNB (Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae).

METHODS

This study analyzed demographic, clinical, and bacteriologic information from 360 infants born 1986-2002 who developed 633 blood culture-proven BSI. A total of 121 EGNB were isolated (E coli, K pneumoniae, and E cloacae). Early-onset BSI were discovered within 48 hours from birth, and late-onset BSI were those that occurred thereafter. Suspected early-onset BSI were treated with ampicillin and gentamicin, suspected late-onset BSI with vancomycin and gentamicin. Antibiotics were changed on the basis of organism antimicrobial susceptibility.

RESULTS

Early-onset BSI were noted in 52 of 21,336 (244/100,000) live births (1986-1991), 40 of 20,402 (196/100,000) live births (1992-1997), and 25 of 17,926 (139/100,000) live births (1998-2002). Of these cases, 39 were caused by E coli and 4 by K pneumoniae. Antibiograms for E coli isolated during the last 5 years of the study showed an increase in antibiotic resistance that coincided with obstetric group B streptococcus antepartum antibiotic prophylaxis. Group B streptococcus declined from 41 to 4 cases from the first to the last period. Late-onset BSI increased from 111 to 230 cases from the first to the second 6-year study period and declined modestly (171 cases) during the last. Fifteen percent (78 cases) of late-onset BSI were caused by EGNB, 5% by other gram-negative bacilli, 67% primarily by coagulase-negative staphylococcus, and 13% by fungus. Nonspecific clinical and hematologic signs of late-onset BSI were similar across EGNB species, but necrotizing enterocolitis was often associated with E coli, whereas pneumonia and prolonged thrombocytopenia characterized K pneumoniae infections. No outbreaks or epidemics were observed, and strains of EGNB with evidence of extended spectrum beta-lactamase production were never isolated.

CONCLUSION

Antepartum antibiotic prophylaxis may have increased antibiotic resistance in E coli isolates from early-onset BSI but has dramatically decreased group B streptococcus infections. Late-onset BSI caused by EGNB increased, but without changes in antibiotic susceptibility. In spite of medical advances, E coli, K pneumoniae, and E cloacae remain responsible for significant morbidity and mortality, especially in very low birth weight infants.

Evaluation and treatment of severe and prolonged thrombocytopenia in neonates

Thrombocytopenia is one of the most common hematologic problems in the neonatal intensive care unit (NICU). Despite its prevalence,several basic pathophysiologic questions remain unanswered. For instance, there is a lack of evidence-based guidelines for treatment,and the kinetic mechanisms (decreased platelet production,increased platelet consumption, or sequestration) responsible for most varieties of neonatal thrombocytopenia are not well defined.Moreover, a clear correlation between degree of thrombocytopenia and the resulting bleeding risk has not been demonstrated, and no transfusion-trigger studies have been conducted in neonates. As a consequence of these deficiencies in knowledge, there is great variability in platelet transfusion practices among NICUs. This article presents an overview of the evaluation of a neonate with severe thrombocytopenia and a review of current and projected therapeutic options.

Alloimmune thrombocytopenias

Alloimmunization against platelet antigens may take place during pregnancy and following transfusion or transplantation. The resulting antibodies bind to the target platelet antigens and may lead to a rapid sequestration of incompatible platelets. The alloimmune thrombocytopenias are classified into neonatal alloimmune thrombocytopenia, post-transfusion purpura, passive alloimmune thrombocytopenia, transplantation-associated alloimmune thrombocytopenia, and platelet transfusion refractoriness. Neonatal alloimmune thrombocytopenia occurs in roughly one of 1,000 births and is the most important type in children. The management of affected infants during pregnancy is yet not established, and the most rapidly effective treatment after delivery is the transfusion of compatible platelets.

Alloimmune thrombocytopenia in the fetus: current management theories

Fetal alloimmune thrombocytopenia (AIT) affects only a small number of fetuses but the consequences may be devastating. Outcomes range from mild thrombocytopenia without signs or symptoms to intracranial hemorrhage (ICH) and fetal or neonatal death. Antenatal screening is available but not used routinely in the United States. The most frequent method of AIT identification is its diagnosis in the neonatal period (index neonate). AIT may be diagnosed antenatally if an ICH is noted on routine obstetric ultrasound. There are accurate predictors of AIT, as well as antenatal therapies, to prevent the occurrence of severe disease and ICH.

Interleukin-11 levels in healthy and thrombocytopenic neonates

Thrombocytopenia is common in sick neonates, and affected neonates have adverse outcomes compared with those without thrombocytopenia. As impaired platelet production underlies many neonatal thrombocytopenias, affected neonates are potential candidates for hemopoietic growth factor therapy. Although recombinant human (rh) thrombopoietin remains under therapeutic development, rhIL-11, which stimulates megakaryocytopoiesis and increases platelet counts after chemotherapy, is already licensed for clinical use. However, nothing is known about IL-11 in neonates. We therefore measured plasma IL-11 by ELISA in healthy term neonates, stable preterm neonates with or without thrombocytopenia, and preterm neonates with sepsis or necrotizing enterocolitis (NEC) with or without thrombocytopenia. At birth IL-11 was undetectable (<10 pg/mL) in healthy term neonates (n = 20) and 27 of 31 (87%) stable preterm neonates. Three stable preterm neonates with detectable IL-11 (mean+/-SD, 11.3 +/- 0.4 pg/mL; median, 11.6 pg/mL) suffered chorioamnionitis, the remaining neonate (IL-11, 14 pg/mL) being one of nine with early onset thrombocytopenia (present by <72 h of age). IL-11 was also measured in 58 preterm neonates with suspected sepsis or NEC. In 25 of 58, sepsis or NEC was unconfirmed and IL-11 was undetectable. By contrast, 14 of 33 with proven sepsis or NEC had elevated IL-11 (median, 14.9 pg/mL; range, 11.2-92.2 pg/mL). Of these 33 neonates, 19 developed thrombocytopenia: nine of 19 (47%) had detectable IL-11 and 10 of 19 (53%) did not (p > 0.05). Although its role in platelet production in neonates remains unclear, these data suggest that IL-11 is involved in the endogenous cytokine response to sepsis or NEC in preterm neonates. Further studies of IL-11 in neonates are warranted to assess its role both in platelet production and in mediation of the endogenous inflammatory response.

Alloimmune thrombocytopenia of the fetus and the newborn

Fetal/neonatal alloimmune thrombocytopenia results from a maternal alloimmunization against fetal platelet antigens. Care must be taken in making a correct diagnosis that eliminates other causes of thrombocytopenia that may occur during pregnancy. Biological diagnosis is normally made by platelet genotyping and search for the maternal alloantibody using monoclonal antibodies in an antigen capture assay. Fetal alloimmune thrombocytopenia, when severe, may result in intracerebral hemorrhage leading to hydrocephalus and death of the fetus. Neonatal alloimmune thrombocytopenia may be present in an otherwise healthy infant. While screening procedures are not in place to detect fetal/neonatal alloimmune thrombocytopenia, it is true that fetal hydrocephalus, unexplained fetal thrombocytopenia with or without anemia, or recurrent miscarriages should be adequate indicators for suspecting fetomaternal alloimmune thrombocytopenia. Multiparous women with a history of giving birth to at least one alloimmune thrombocytopenic infant should be carefully monitored in subsequent pregnancies. Postnatal management of neonatal alloimmune thrombocytopenia involves compatible platelet transfusion in the neonate. Antenatal management of fetal alloimmune thrombocytopenia is controversial and includes a combination of maternal intravenous gamma globulin (i.v.IgG) administration, intrauterine platelet transfusions, and corticosteroid therapy, while monitoring fetal platelet counts closely throughout the course of pregnancy. Screening of pregnant women may become a public health issue only after antenatal therapy is more standardized.