Thromboembolic Diseases in Neonates and Children

Cerebral venous thrombosis and deep medullary vein thrombosis: Padua experience over the last two decades

BACKGROUND

Cerebral venous thrombosis (CVT) is a cerebrovascular disorder that accounts for 20% of perinatal strokes. CVT incidence ranges from 0.67 to 1.12 per 100,000 newborns, while the incidence of "deep medullary vein thrombosis" (DMVT), a subtype of CVT, cannot be accurately estimated. This study aims to analyze the case history of CVT in the neonatal period, with a specific focus on DMVT.

MATERIALS AND METHODS

Newborns diagnosed with CVT, with or without DMVT, between January 2002 and April 2023, were collected using the Italian Registry of Infantile Thrombosis (RITI). Cerebral MRIs were reviewed by an expert neuroradiologist following a standardized protocol.

RESULTS

Forty-two newborns with CVT were identified, of which 27/42 (64%) had CVT, and the remaining 15/42 (36%) had DMVT (isolated DMVT in 9/15). Symptom onset occurred in the first week of life (median 8 days, IQR 4-14) with a male prevalence of 59%. The most common risk factors for CVT were complicated delivery (38%), prematurity (40%), congenital heart diseases (48%), and infections (40%). Seizures were the predominant presenting symptom in 52% of all cases. Hemorrhagic infarction was higher in cases with isolated DMVT (77%) compared to patients with CVT without DMVT (p = 0.013). Antithrombotic treatment was initiated in 36% of patients. Neurological impairment was observed in 48% of cases at discharge, while 18 out of 31 infants (58%) presented one or more neurological deficits at long term follow up.     Conclusion: DMVT occurs in over a third of neonates with CVT. Multicentric studies are essential to establish standardized protocols for therapy, neuroimaging, and follow-up in these patients.

Thromboelastometry in Neonates with Respiratory Distress Syndrome: A Pilot Study

BACKGROUND

Although respiratory distress syndrome (RDS) constitutes a postnatal risk factor for bleeding and thromboembolic events in neonates, few studies have addressed this issue. We aimed to evaluate the hemostatic profile of neonates with RDS using rotational thromboelastometry (ROTEM).

METHODS

An observational study was conducted from November 2018 to November 2020 in the NICU of General Hospital of Nikaia "Aghios Panteleimon". Preterm and term neonates with RDS hospitalized in the NICU were included and EXTEM (tissue factor-triggered extrinsic pathway), INTEM (ellagic acid activated intrinsic pathway), and FIBTEM (with platelet inhibitor cytochalasin D) assays were performed at the onset of the disease.

RESULTS

A hypocoagulable profile was noted in neonates with RDS compared to controls, expressed as significant prolongation of EXTEM CT (clotting time) and CFT (clot formation time), lower EXTEM A10 (amplitude at 10 min), MCF (maximum clot firmness), and LI60 (lysis index). Furthermore, prolongation of INTEM CFT and FIBTEM CT, and decreased INTEM and FIBTEM A10 and MCF were found in neonates with RDS. Multivariable logistic regression analysis showed that RDS is an independent factor for the recorded alterations in ROTEM variables.

CONCLUSIONS

RDS is associated with a hypocoagulable profile and greater hyperfibrinolytic potential compared to healthy neonates.

Intracranial haemorrhage in late-onset neonatal group B streptococcal disease: A case report

This report aims to alert clinicians to the possibility of intracerebral haemorrhage as a rare manifestation of late-onset neonatal group B streptococcal (LOGBS) disease. This case also highlights the need for effective treatment guidelines for LOGBS disease. We report a case of LOGBS disease in a 17-day-old full-term female neonate, complicated by bilateral subarachnoid haemorrhage confirmed on magnetic resonance imaging (MRI). The patient presented with fever, lethargy, and convulsions. Microbiological examination confirmed the presence of Streptococcus agalactiae in the blood culture. Brain MRI showed bilateral subarachnoid haemorrhage and diffuse cerebral ischaemia, suggesting a severe complication of LOGBS disease. Short-term follow-up of the patient showed marked developmental delay. Early screening for group B streptococcus infection in pregnant women is essential to prevent severe cases of LOGBS disease. Very few cases of intracerebral haemorrhage in LOGBS disease have been reported. Further evidence is required to support a pertinent link between LOGBS disease and intracerebral haemorrhage.

The role of thrombophilia genes in the clinical implementation of arterial and venous thrombosis in newborns

The article considers the analysis results of the occurrence frequency of genotypes and alleles of plasma, platelet and fibrinolytic hemostasis in full-term newborns with arterial and venous thrombosis of various localization. Gene polymorphisms were studied by real-time PCR in human DNA samples obtained from buccal epithelium and venous blood lymphocytes. The control group was a group of healthy full-term newborns from families without a thrombophilic history. Predictors of arterial and venous thrombosis in children are such as polymorphism of the plasminogen activator inhibitor gene PAI-1-675 4G/4G (OR=5,6 [2,3-13,8]), combinations of polymorphisms PAI-1-675 4G/4G + factor VII G10976A G/G (OR=5,8 [1,7-19,1]), combinations of polymorphisms PAI-1 -675 4G/4G + factor VII G10976A G/G + factor XIII Val34Leu G/G (% AR=61), fibrinogen FGB -455 G/A (OR=3,75 [1,4-9,4]) and integrin alpha 2 ITGA2 807 T/T (OR=15,56 [1,9-126,7]). Thus, the study of polymorphisms of the plasminogen activator inhibitor, fibrinogen, integrin alpha 2 can serve as one of the criteria for identifying a high-risk group for the development of arterial and venous thrombosis in newborns and should be taken into account when evaluating individual thrombophilia risk.

Neonatal cerebral sinovenous thrombosis

Cerebral sinovenous thrombosis (CSVT) is a focal or diffuse disruption of cerebral blood flow secondary to occlusion of cerebral veins and/or sinuses. The challenge of CSVT during the neonatal age has led to a great interest in this condition among neonatologists, child neurologists, and pediatric neuroradiologists. The highly variable clinical spectra, etiologies, and prognosis require fine medical skills and a high level of suspicion. Nevertheless, the diagnosis is often delayed or missed altogether. Differences in brain vulnerability at different stages of maturation may explain the spectrum of associated brain lesions, which varies with gestational age. Treatment is controversial and reported clinical outcomes vary widely. The controversial treatment of CSVT with anticoagulant therapy is based only on case series and expert consensus, there is lack of safety data.

Clinical Data of Neonatal Systemic Thrombosis

OBJECTIVE

To evaluate clinical data and associated risk conditions of noncerebral systemic venous thromboembolism (VT), arterial thromboembolism (AT), and intracardiac thromboembolism (ICT) in neonates.

STUDY DESIGN

Data analysis of first systemic thromboembolism occurring in 75 live neonates (0-28 days), enrolled in the Italian Registry of Pediatric Thrombosis from neonatology centers between January 2007 and July 2013.

RESULTS

Among 75 events, 41 (55%) were VT, 22 (29%) AT, and 12 (16%) ICT; males represented 65%, and 71% were preterm. In 19 (25%), thromboembolism was diagnosed on the first day of life. In this "early onset" group, prenatal-associated risk conditions (maternal/placental disease) were reported in 70% and inherited thrombophilia in 33%. Postnatal risk factors were present in 73%; infections and central vascular catheters in 56% and 54% VT, respectively, and in 67% ICT vs 27% AT (<.05). Overall mortality rate was 15% and significant thromboembolism-related sequelae were reported in 16% of discharged patients.

CONCLUSIONS

This report from the Registro Italiano Trombosi Infantili, although limited by representing an uncontrolled case series, can be used to develop future clinical trials on appropriate management and prevention of neonatal thrombosis, focusing on obstetrical surveillance and monitoring of critically ill neonates with vascular access. A thrombosis risk prediction rule specific for the neonatal population should be developed through prospective controlled studies.

Thrombosis in the Neonatal Intensive Care Unit

Neonates have the highest risk for pathologic thrombosis among pediatric patients. A combination of genetic and acquired risk factors significantly contributes to this risk, with the most important risk factor being the use of central venous catheters. Proper imaging is critical for confirming the diagnosis. Despite a significant number of these events being life- and limb-threatening, there is limited evidence on what the appropriate management strategy should be. Evaluation and treatment of any neonate with a clinically significant thrombosis should occur at a tertiary referral center that has proper support.

Prothrombotic risk factors and antithrombotic therapy in children with ischemic stroke

OBJECTIVE

Congenital and acquired prothrombotic disorders have been highlighted in a recent series of cerebrovascular stroke (CVS), with a controversial role in pathogenesis. The aim is to study some prothrombotic risk factors [activated protein C (APC) resistance, von Willebrand factor (vWF), anticardiolpin (ACL) antibodies and plasma homocysteine] in children with ischemic stroke, and to evaluate the role of aspirin and low molecular weight heparin (LMWH) in its management in relation to outcome.

METHODS

A total of 37 cases aged from 1 month to 15 years ( mean ± standard deviation 26.2 ± 35.7 months), diagnosed as ischemic stroke (>24 hours) were recruited. Complete blood count, prothrombin time and concentration, partial thromboplastin time, serum electrolytes, random blood sugar, C-reactive protein, electrocardiogram and echocardiography were done. Levels of APC resistance, vWF, ACL antibodies [immunoglobulin G (IgG) and immunoglobulin M (IgM)] and plasma homocysteine were estimated. A total of 25 cases received aspirin 3-5 mg /kg/d and 12 patients received LMWH as initial dose at 75 international units (IU)/kg subcutaneously (SC) then 10-25 IU/kg/day for 15 days in a nonrandomized fashion.

RESULTS

The levels of APC resistance, vWF, ACL antibodies (IgG and IgM) and plasma homocysteine were significantly higher in stroke cases than in controls. There was no significant difference between cases treated with aspirin and those with LMWH in all prothrombotic factors. Significant positive correlations were found between vWF and ACL antibodies (IgG and IgM) levels before treatment. Significant decrease in cognitive function was detected between cases treated with LMWH and those treated with aspirin.

CONCLUSION

Ischemic CVS in children is multifactorial. Thrombophilia testing should be performed in any child with CVS. Early use of aspirin improves the prognosis and has less effect on cognitive function.

Neonatal haemostasis and the management of neonatal thrombosis

Two detailed reviews of the management of neonatal thrombosis were published in 2012; one was an up-dated version of guidance first issued in 2004 and the other was a comprehensive review. Both of these publications gave very similar advice regarding the practical aspects of the indications, dosage and management of antithrombotic therapy. The authors stated that the evidence supporting most of their recommendations for anti-thrombotic therapy in neonates remained weak and so the therapy for a neonate with a thrombosis has to be based on an individualized assessment of estimated risk versus potential benefit. The aim of this present review is to give the treating physician an outline of the unique physiology of neonatal coagulation and how this affects the monitoring, dosing and even the choice of therapeutic strategy for the management of thrombosis in the neonate.

Neonatal stroke: a review of the current evidence on epidemiology, pathogenesis, diagnostics and therapeutic options

Neonatal stroke, including perinatal arterial ischaemic stroke and cerebral sinovenous thrombosis, remains a serious problem in the neonate. This article reviews the current evidence on epidemiology, pathogenesis, diagnostics and therapeutic options.

CONCLUSION

Although our understanding of the underlying mechanisms and possible risk factors has improved, little progress has been made towards therapeutic options. Considering the high incidence of neurological sequelae, the need for therapeutic options is high and should be the focus of future research.

Management of neonatal thrombosis

Neonates have one of the highest risks for thromboembolism among pediatric patients. This risk is attributable to a combination of multiple genetic and acquired risk factors. Despite a significant number of these events being either life threatening or limb threatening, there is limited evidence on appropriate management strategy. Most of what is recommended is based on uncontrolled studies, case series, or expert opinion. This review begins with a discussion of the neonatal hemostatic system, focusing on the common sites and imaging modalities for the detection of neonatal thrombosis. Perinatal and postnatal risk factors are presented and management options discussed.

Intrauterine extremity gangrene and cerebral infarction at term: a case report

Intrauterine extremity gangrene in combination with cerebral infarction is a serious and rare event. We present a case with a healthy mother who gave birth to a child with this condition. At term, the mother presented at the antenatal clinic with decreased fetal movements. Cardiotocography (CTG) showed signs of fetal distress and a caesarean section was performed. The left arm of the newborn was found gangrenous. Amputation of the arm was necessary and the child was subsequently treated with anticoagulant therapy due to thrombosis and cerebral infarction in the left hemisphere found by magnetic resonance imaging (MRI). At one year of age the boy was doing well and had prosthesis as a left arm. He had no signs of further complications. Despite thorough examination of the parents and the child, the reason for the thrombosis is still unknown.

Diagnosis and management of neonatal thrombocytopenia

Thrombocytopenia is the most common haematological abnormality in newborns admitted to neonatal care units and serves as an important indicator of underlying pathological processes of mother or child. In most cases thrombocytopenia is mild to moderate and resolves within the first weeks of life without any intervention. However, in some neonates thrombocytopenia is severe or may reflect an inborn platelet disorder. As clinical course and outcome of thrombocytopenia depend on the aetiology of thrombocytopenia, an appropriate work-up is essential to guide therapy in neonates with thrombocytopenia and to avoid severe bleeding.

Two children with both arm ischemia and arterial ischemic stroke during the perinatal period

It is rare for both limb ischemia and arterial ischemic stroke to occur in the same child during the perinatal period. Two children who appear to have had perinatal emboli to both an arm and a middle cerebral artery territory are presented here. One child required amputation of the ischemic limb below the shoulder, and the other required skin grafts to the distal ischemic fingers. Each of these children later received cerebral magnetic resonance imaging for evaluation of developmental delay and was found to have what appeared to be old perinatal arterial ischemic stroke. Both children were homozygous for the methylenetetrahydrofolate reductase C677T gene variant. Eight other children with perinatal limb ischemia and stroke were found on literature review; several also had delayed diagnosis of perinatal stroke. This report examines the approach to diagnosis and treatment in each of these and makes suggestions for the similar cases in the future.

Thrombus obstructing the right ventricle outflow tract in a neonate with methylenetetrahydrofolate reductase 677TT genotype

At her first day of life, a neonate presented with severe cyanosis and a mass obstructing the right ventricle outflow tract. Prostagladin E1 was necessary to provide pulmonary blood flow. The mass was removed using extracorporeal bypass surgery; the right ventricle was dilated, and the pulmonary valve leaflets were damaged. Sternal closure was delayed because of bleeding and poor cardiac performance. Histology demonstrated that the mass was a mixed thrombus. Investigation revealed homozygous 677TT genotype of the methylenetetrahydrofolate reductase. In conclusion, a life-threatening thrombotic event such as an intracardiac thrombus obstructing the right ventricle outflow tract can occur in a neonatal age. Since the event can be a result of a combination of acquired and congenital thrombogenic risk factors, an extensive screening including DNA-based mutation analysis should be performed.

Central venous catheters in neonates: from simple monolumen to port catheter

The use of central venous catheters (CVCs) represents an important step in the management of the surgical, onco-hematology and critically ill patients. CVCs in neonates, like in adult patients, are mainly used to infuse hyperosmolar solutions, to take blood samples and for hemodynamic monitoring. The need for CVCs is higher in neonates than in adults. Poor peripheral access and the high demand for IV access and blood samples are already valuable indications for a CVC.

Cobalamin C defect: natural history, pathophysiology, and treatment

Cobalamin C (Cbl-C) defect is the most common inborn cobalamin metabolism error; it causes impaired conversion of dietary vitamin B12 into its two metabolically active forms, methylcobalamin and adenosylcobalamin. Cbl-C defect causes the accumulation of methylmalonic acid and homocysteine and decreased methionine synthesis. The gene responsible for the Cbl-C defect has been recently identified, and more than 40 mutations have been reported. MMACHC gene is located on chromosome 1p and catalyzes the reductive decyanation of CNCbl. Cbl-C patients present with a heterogeneous clinical picture and, based on their age at onset, can be categorized into two distinct clinical forms. Early-onset patients, presenting symptoms within the first year, show a multisystem disease with severe neurological, ocular, haematological, renal, gastrointestinal, cardiac, and pulmonary manifestations. Late-onset patients present a milder clinical phenotype with acute or slowly progressive neurological symptoms and behavioral disturbances. To improve clinical course and metabolic abnormalities, treatment of Cbl-C defect usually consists of a combined approach that utilizes vitamin B12 to increase intracellular cobalamin and to maximize deficient enzyme activities, betaine to provide a substrate for the conversion of homocysteine into methionine through betaine-homocysteine methyltransferase, and folic acid to enhance remethylation pathway. No proven efficacy has been demonstrated for carnitine and dietary protein restriction. Despite these measures, the long-term follow-up is unsatisfactory especially in patients with early onset, with frequent progression of neurological and ocular impairment. The unfavorable outcome suggests that better understanding of the pathophysiology of the disease is needed to improve treatment protocols and to develop new therapeutic approaches.

Neonatal thrombo-embolism: risk factors, clinical features and outcome

BACKGROUND

There are few data with respect to prothrombotic risk factors in neonates.

AIM

To determine the associated risk factors, clinical features and outcome in newborn infants diagnosed with thrombo-embolism.

METHODS

Case records of 25 infants (17 full-term and eight preterm) diagnosed with thrombo-embolism between January 2005 and April 2008 in a neonatal intensive care unit were reviewed.

RESULTS

Of the 25 infants, 18 cases of venous (72%) and seven of arterial (28%) thrombo-embolism were recorded; in 18 it was associated with central catheterisation. The sites of thrombosis were portal vein (15), right renal vein (one), right femoral vein (one), multiple veins (one), right femoral artery (3), right iliac artery (2), bilateral iliac and renal arteries (one) and left renal artery (one). Hereditary thrombotic mutations were detected in three patients and anticardiolipin antibody was detected in one, none of whom had been catheterised. The remaining three non-catheterised patients had perinatal risk factors. Venous catheter placement was undertaken in 12 patients (48%), eleven of whom had: umbilical venous catheterisation for exchange transfusion (9), partial exchange transfusion (one) and venous access (one), and one had femoral venous catheterisation for an angiographic study. Arterial catheterisation was undertaken in seven patients (28%) (one infant had both umbilical venous and arterial catheters) for angiographic studies (5) and blood sampling (2). Of the 18 catheterised patients (72%), thrombophilic studies were undertaken in 13 and none had abnormal results. Additional perinatal risk factors were present in 18 patients (72%) and included prematurity (8), congenital heart disease (8), septicaemia (5), dehydration (3), respiratory distress syndrome (3), polycythemia (2), meconium aspiration syndrome (one), pneumonia (one), maternal diabetes (one), necrotising enterocolitis (one) and perinatal asphyxia (one). Although most of the patients recovered after anticoagulant or fibrinolytic therapy, the five (20%) deaths were associated mainly with underlying diseases.

CONCLUSION

The most important risk factor for thrombo-embolic events in neonates is placement of central catheters and some perinatal prothrombotic conditions. Nevertheless, hereditary or acquired thrombophilic risk factors may also be a cause of thrombo-embolism.

Preterm arterial ischemic stroke

Most studies about perinatal arterial ischemic stroke (PAIS) exclude preterm infants. In a prospectively studied hospital-based population, 42% of our 73 newborn infants with PAIS had a gestational age (GA) < or =36 weeks. PAIS was present on the left in 61% of the preterm infants and bilateral in 7%. The middle cerebral artery (MCA) was most often affected. Involvement of the lenticulostriate branches was common among preterm infants with GA of 28-32 weeks, and involvement of the MCA main branch was seen in almost all with a GA>33 weeks. Twin-to-twin transfusion syndrome, fetal heart rate abnormality and hypoglycemia were independent risk factors. No maternal risk factors could be identified. Comparing neurodevelopmental outcome, infants with a main branch MCA infarct, irrespective of being preterm or full-term, were found to be most at risk of motor/cognitive impairment. Preterm infants with PAIS had more language problems at 2 years of age.

The evaluation and management of postnatal thromboses

In the pediatric population, neonates have the highest risk for thromboembolism (TE), most likely due to the frequent use of intravascular catheters. This increased risk is attributed to multiple risk factors. Randomized clinical trials dealing with management of postnatal thromboses do not exist, thus, opinions differ regarding optimal diagnostic and therapeutic interventions. This review begins with an actual case study illustrating the complexity and severity of these types of cases, and then evaluates the neonatal hemostatic system with discussion of the common sites of postnatal thrombosis, perinatal and prothrombotic risk factors, and potential treatment options. A proposed step-wise evaluation of neonates with symptomatic postnatal thromboses will be suggested, as well as future research and registry directions. Owing to the complexity of ischemic perinatal stroke, this topic will not be reviewed.

The evaluation and management of neonatal coagulation disorders

Neonatal hemostatic abnormalities can present diagnostic and therapeutic challenges to the physician. Developmental deficiencies and/or increases of certain coagulation proteins, coupled with acquired or genetic risk factors, can result in a hemorrhagic or thromboembolic emergency. The timely diagnosis of a congenital hemorrhagic or thrombotic disorder can avoid significant long-term sequelae. However, due to the lack of randomized clinical trials addressing the management of neonatal coagulation disorders, treatment strategies are usually empiric and not evidence-based. In this chapter, we will review the neonatal hemostatic system and will discuss the most common types of hemorrhagic and thrombotic disorders. Congenital and acquired risk factors for hemorrhagic and thromboembolic disorders will be presented, as well as current treatment options. Finally, suggested evaluations for neonates with either hemorrhagic or thromboembolic problems will be reviewed.

Unilateral venous thalamic infarction in a child mimicking a thalamic tumor

Unilateral thalamic infarction is a rare condition in adults. This is a case report of a young child presenting with left-sided hemiparesis of sudden onset due to an unilateral venous thalamic infarction. This was attributed to an asymmetric thrombosis of the cerebral internal veins, a partial thrombosis of the vein of Galen and straight sinus. Magnetic resonance imaging resulted primarily in the differential diagnosis of a cerebral tumor or an intracerebral abscess, leading to stereotactic puncture. Subsequent magnetic resonance venography facilitated the correct diagnosis. Heparin-induced thrombocytopenia necessitated anticoagulation treatment with hirudin and later, warfarin. The patient made a complete recovery. We conclude that unclear unilateral thalamic lesions might be symptomatic of a cerebral deep venous thrombosis and might mimic a thalamic tumor. In uncertain cases, we suggest rapid performance of magnetic resonance angiography.

Low-Molecular-Weight Heparin Use in a Case of Noncardiogenic Multifocal Perinatal Thromboembolic Stroke

A full-term neonate suffered multifocal cerebral infarctions due to multiple large vessel thrombi. Thrombophilia and cardiovascular assessments were negative, but due to the severity of the lesions and the concern for expansion of the thrombi or future embolic events, treatment with low-molecular-weight heparin (LMWH) was initiated. No complications from treatment were experienced. We present this severe case in order to highlight difficult management decisions for newborns with multifocal perinatal thromboembolic stroke and to stress the need for further practice guidelines and research in this area.

Incidence of and risk factors for childhood thrombosis: a single-center experience in Ankara, Turkey

This study was conducted to analyze the incidence of and risk for thrombosis in thrombotic children monitored in the Department of Pediatric Hematology of our hospital at the time of diagnosis, in addition to the clinical characteristics of those patients. The clinical and laboratory findings of 122 patients diagnosed with thrombosis from 1997 to 2006 were retrospectively analyzed. The incidence of thrombosis was 88.6/10,000 hospital admissions. The authors found that 31.1% of the patients studied had a thrombosis in more than 1 region. The incidence of thrombosis by anatomic site was as follows: 42 thromboses in the peripheral arterial system, 39 in an intracardiac region, 38 in the abdominal venous system, 36 in the deep peripheral venous system, and 28 in the cerebral vascular system. The mean age of the patients at the time of diagnosis was 4.9 years. Of the patients studied, 10.7% were neonates, 35.3% were infants younger than 1 year, and 48.4% were younger than 2 years. Most of the patients had a congenital cardiac disease and spontaneous thrombosis, and 66.1% had at least 1 acquired risk factor, the most common of which were having undergone surgery (42%) or wearing a central venous catheter (39%). A hereditary factor for the development of thrombosis was present in 54% of the patients. The most frequently observed hereditary risk factor was the MTHFR 677C-T mutation, and the second most common was the factor V Leiden mutation. Thrombosis should be considered a systemic disorder, and thrombotic patients should be evaluated with appropriate methods. Acquired and hereditary risk factors should be analyzed systematically in thrombotic patients.

Risk factors for umbilical venous catheter-associated thrombosis in very low birth weight infants

BACKGROUND

Thrombosis in neonates is a rare but serious occurrence, usually associated with central catheterization. The objective of this study was to investigate the risk factors associated with catheter related thrombosis in very low birth weight (VLBW) infants.

PROCEDURE

The present retrospective study was performed using data from a randomized trial of duration of umbilical venous catheters (UVC) placement among infants <1,250 g birth weight. Twenty-two cases of UVC-associated thrombosis were identified in this sample. The remaining study sample (n = 188) served as the comparison group. Data on thrombosis, platelets, gestational age, birth weight, hematocrit, serum sodium, maternal preeclampsia, blood group, infant of diabetic mother (IDM) and demographic factors were collected using database and record review.

RESULTS

Among the total subjects (n = 210), 112 (53%) were males and 126 (60%) were Caucasians, with mean gestational age of 27.7 +/- 2.1 weeks (standard deviation) and mean birth weight of 923 +/- 195 g. Bivariate analysis revealed significant association of thrombosis with hematocrit >55% in the first week (odds ratio [OR] 5.4; 95% confidence interval [CI] 2.0-14.6; P = 0.0003), being small for gestational age (SGA) (OR, 2.9; 95% CI, 1.2-7.4; P = 0.02) and maternal preeclampsia (OR, 3.97; 95% CI, 1.6-9.84; P = 0.0017). In multivariate logistic regression analysis, only hematocrit >55% was independently associated with thrombus (OR, 3.7; 95% CI 1.1-11.8; P = 0.03).

CONCLUSIONS

This study demonstrates a significant, independent association between elevated hematocrit and development of UVC-associated thrombosis. Careful monitoring for catheter-associated thrombosis may be indicated in VLBW infants who have hematocrit >55% in the first week of life.

Thrombophilia screening in asymptomatic children

Children with a family history of thrombophilia and/or thrombosis are often referred to pediatric thrombosis centers for evaluation. This article reviews the risks and benefits of thrombophilia testing in this unique population. The article also reviews an approach to testing including a step-wise evaluation and involvement of a genetic counselor.

Evaluation of the Coagulation System in Children with Two-Ventricle Congenital Heart Disease

BACKGROUND

Multiple coagulation factor abnormalities involving both procoagulant and anticoagulant proteins have been described in children with single-ventricle physiology. This study used age-matched controls to evaluate coagulation factors in children with two-ventricle congenital heart disease (CHD).

METHODS

Coagulation factors were assayed in 120 patients with CHD, divided into four age groups: group 1, 0 to 3 months; group 2, 3 to 12 months; group 3, 12 to 48 months; and group 4, older than 48 months. Healthy children without CHD were assayed as controls. Concentration of factors II, V, VII, VIII, IX, and X; protein C and S, plasminogen, and antithrombin III, were measured by standard assays. Normal ranges were determined by the empirical 95% confidence intervals.

RESULTS

Significant reductions were found in mean levels of both procoagulant and anticoagulant factors in patients in groups 1, 2, and 3 compared with controls, but no differences were found in group 4. In group 1, all variables had significantly lower concentrations except fibrinogen and protein S; in group 2, all variables had significantly lower concentrations except for fibrinogen, factors VIII and IX, and plasminogen and protein S; and in group 3, all variables had significantly lower concentrations except fibrinogen, factors VIII and IX, and antithrombin III, plasminogen, and protein S.

CONCLUSIONS

Neonates and infants with two-ventricle CHD have lower levels of procoagulant and anticoagulant factors compared with aged-matched controls approaching normal levels in children aged older than 4 years. These coagulation factor abnormalities are similar to those described in patients with single-ventricle physiology.

Neonatal thromboembolic emergencies

Thrombosis risk is multifactorial, with interaction of hereditary risk factors and acquired environmental and clinical conditions. Newborns are at particular risk for thrombotic emergencies secondary to the unique properties of their hemostatic system, influences of the maternal-fetal environment, and perinatal complications and interventions. Thrombotic complications range from arterial and venous catheter thrombosis to purpura fulminans. Prompt identification and appropriate management of thrombotic emergencies is critical in avoiding limb-, organ-, and life-threatening complications. Treatment strategies have been extrapolated from adult literature but clinical experience from small-scale neonatal studies has resulted in therapeutic guidelines, which should be individualized for each neonate, taking into consideration age and clinical status.

Iliofemoral Deep Vein Thrombosis in Childhood; Developing a Management Protocol

OBJECTIVE

To develop an evidence-based protocol for the management of iliofemoral deep vein thrombosis (IDVT) in childhood.

METHODS

A search of the literature was undertaken. All publications pertaining to IDVT in childhood were analysed and then categorised according to their level of evidence. Recommendations were then made on the basis of this.

RESULTS

The commonest presenting symptoms were pain and swelling in the affected limb (evidence level II). Predisposing risk factors of special significance in children included the recent use of a venous access device, malignancy, prothrombotic disorders, infection, surgery and congenital venous anomalies (evidence level II). The most frequently described imaging modalities were B-mode ultrasonography, duplex, venography, and helical CT (evidence level III). The mainstay of treatment was anticoagulation with LMWH alone or followed by warfarin (evidence level I). Early clot removal through catheter-directed thrombolysis or surgical thrombectomy has been shown to be beneficial (evidence level II/III). There is little evidence for the benefit of early mobilisation and compression therapy in childhood.

CONCLUSION

Level I evidence relating to IDVT in childhood is sparse. The possibility of IDVT should be considered when examining a child with a swollen and painful limb. Imaging should be with duplex ultrasound, followed by spiral CT to include assessment of the IVC. A thrombophilia screen should be taken prior to anticoagulation with LMWH (and warfarin). Thrombolysis should be considered in cases of extensive IDVT.

A giant thrombus in the right ventricle of a newborn with Down syndrome: successful treatment with rt-PA

An association between thromboembolic events and Down syndrome (DS) has been increasingly reported in the literature. It is not clear whether patients with DS have increased risk for thrombotic disorders or there is a coincidence. We present a case of giant right ventricular thrombus in a neonate with DS. Risk factors for thrombosis in the present case were neonatal sepsis and dehydration. There was no congenital heart anomaly. The patient was treated successfully using recombinant tissue plasminogen activator. Recombinant tissue plasminogen activator seems to be a safe and effective thrombolytic therapy in neonates.

The rule of four: a systematic approach to diagnosis of common pediatric hematologic and oncologic disorders

The "Rule of Four" facilitates a rapid and focused approach to the diagnosis of the common hematologic and oncologic disorders encountered in general pediatric practice. This system relies on four recurrent but different clinical entities or laboratory tests relevant to the diagnosis of children with anemia, excessive bleeding or clotting, and common malignancies. For each disorder, there is a discussion of a variety of four lab tests or factors pertinent to a differential diagnosis.