Laboratory Testing for Thrombophilia in Pediatric Patients

Renal vein thrombosis in neonates: a case series of diagnosis, treatment and childhood kidney function follow-up

BACKGROUND

Neonatal renal vein thrombosis (NRVT) is a rare condition with little data available.

METHODS

We retrospectively analyzed newborns diagnosed with NRVT admitted to 3 pediatric nephrology units in Paris from 2005 to 2020.

RESULTS

Twenty-seven patients were analyzed (male = 59%). The median age at diagnosis was 2.5 days (1 - 4.5). Diagnosis was suspected based on at least one of the three cardinal signs of renal vein thrombosis in 93%: flank mass (67%), hematuria (67%) and thrombocytopenia (70%). In all patients, diagnosis was confirmed by ultrasound. All patients had at least one known perinatal risk factor. A prothrombotic risk factor was found in 13 patients (48%). NRVT was unilateral in 70%, involving the left renal vein in 58%. Among 25 treated patients, 19 (76%) received low molecular weight heparin (LMWH) as initial therapy, 2 (8%) received unfractionated heparin and 4 (16%) received fibrinolysis. Median duration of treatment was 8 weeks (4 - 12). Bleeding occurred significantly more often with fibrinolysis than with LMWH/supportive therapy (3 of 4: 75% vs 0 of 4: 0%, p = 0.05). Clot resolution in patients treated with fibrinolysis did not differ significantly from those treated with LMWH/supportive therapy. After a median follow-up of 5.7 years (3 years - 9.9 years), pathological kidney features were observed in 73% of the patients (19 of 26), kidney atrophy in 18 (69%), hypertension in 2 (8%), chronic kidney disease (CKD) in 1 (4%) and proteinuria in 2 (8%).

CONCLUSIONS

NRVT remains a challenging condition, which still requires further study because of its associated morbidity. A higher resolution version of the Graphical abstract is available as Supplementary information.

Hemostatic and Thrombotic Considerations in the Diagnosis and Management of Childhood Arterial Ischemic Stroke: A Narrative Review

Although rare in children, arterial ischemic stroke (AIS) is associated with increased mortality and neurological morbidity. The incidence of AIS after the neonatal period is approximately 1-2/100,000/year, with an estimated mortality of 3-7%. A significant proportion of children surviving AIS experience life-long neurological deficits including hemiparesis, epilepsy, and cognitive delays. The low incidence of childhood AIS coupled with atypical clinical-presentation and lack of awareness contribute to delay in diagnosis and consequently, the early initiation of treatment. While randomized-clinical trials have demonstrated the efficacy and safety of reperfusion therapies including thrombolysis and endovascular thrombectomy in appropriately-selected adult patients, similar data for children are unavailable. Consequently, clinical decisions surrounding reperfusion therapy in childhood AIS are either extrapolated from adult data or based on local experience. The etiology of childhood AIS is multifactorial, often occurring in the setting of both acquired and congenital risk-factors including thrombophilia. While multiple studies have investigated the association of thrombophilia with incident childhood AIS, its impact on stroke recurrence and therefore duration and intensity of antithrombotic therapy is less clear. Despite these limitations, a significant progress has been made over the last decade in the management of childhood AIS. This progress can be attributed to international consortiums, and in selected cohorts to federally-funded clinical trials. In this narrative review, the authors have systematically appraised the literature and summarize the hemostatic and thrombotic considerations in the diagnosis and management of childhood AIS focusing on the evidence supporting reperfusion therapies, relevance of thrombophilia testing, and duration and drug choices for secondary-prophylaxis.

Implementation of automatic data extraction from an enterprise database warehouse (EDW) for validating pediatric VTE decision rule: a prospective observational study in a critical care population

Multiple clinical risk prediction tools for hospital acquired venous thromboembolism (HA-VTE) have been developed. The objectives of this study were to develop and assess the feasibility of data extraction from Electronic Medical Records (EMR) from an enterprise database warehouse (EDW) and to test the validity of a previously developed Pediatric Clot Decision Rule (PCDR). This single-center prospective observational cohort study was conducted between March 2016 and March 2017 and included eligible patients admitted to the intensive care units. Risk score was calculated using the PCDR tool. Sensitivity, specificity, positive and negative predicted value (PPV and NPV) were calculated based on a cut-point of 3. A total of 2822 children were eligible for analysis and 5.1% (95% CI 4.2-6.2) children had a PCDR score of 3. Children with PCDR score of ≥ 3 had a 3 times higher odd of developing VTE compared to those with scores < 3 (OR 3.1; 95% CI 1.93-4.80; p < 0.001). The model performance showed that at the cutoff point of ≥ 3, both the specificity and sensitivity of the PCDR in predicting VTE was 69% and NPV of 98%. We successfully demonstrated using our EDW to populate a research database using an automatic data import. A PCDR score of ≥ 3 was associated with VTE. Collaboration through large registries will be useful in informing practices and guidelines for rare disorders such as pediatric VTE.

Community-Onset Venous Thromboembolism in Children: Pediatric Emergency Medicine Perspectives

Pediatric venous thromboembolism (VTE) is a condition increasingly encountered by emergency medicine physicians. Unfortunately, despite increased incidence, the diagnosis of pediatric VTE relies on a high index of suspicion from clinicians. Delays in diagnosis and initiation of treatment can lead to poor outcomes in children, including an increased risk of mortality from pulmonary embolism, increased risk of VTE recurrence, and the development of the post-thrombotic syndrome. The majority of pediatric VTE events are associated with the presence of at least one underlying prothrombotic risk. Timely recognition of these risk factors in the emergency department (ED) setting is paramount for a prompt diagnosis and treatment initiation. Compared with children with hospital-acquired VTE, children presenting to the ED with new onset VTE tend to be older (>11 years of age), have a lower incidence of co-morbidities, and present more frequently with a deep venous thrombosis of the lower extremity. Currently, there are no validated pediatric-specific VTE clinical pretest probability tools that reliably assist with the accurate and timely diagnosis of pediatric VTE. Compression ultrasound with Doppler is the most common imaging modality used for VTE diagnosis, and low molecular weight heparins are the most common anticoagulants initiated in children presenting with VTE in the ED. Special consideration should be given to patients who present to the ED already on anticoagulation therapy who may require acute management for clinically-significant bleeding or change in antithrombotic therapy approach for progression/recurrence of VTE.

Updated recommendations for the treatment of venous thromboembolism

Venous thromboembolism (VTE), which includes pulmonary embolism and deep vein thrombosis, is a condition characterized by abnormal blood clot formation in the pulmonary arteries and the deep venous vasculature. It is often serious and sometimes even fatal if not promptly and appropriately treated. Moreover, the later consequences of VTE may result in reduced quality of life. The treatment of VTE depends on various factors, including the type, cause, and patient comorbidities. Furthermore, bleeding may occur as a side effect of VTE treatment. Thus, it is necessary to carefully weigh the benefits versus the risks of VTE treatment and to actively monitor patients undergoing treatment. Asian populations are known to have lower VTE incidences than Western populations, but recent studies have shown an increase in the incidence of VTE in Asia. A variety of treatment options are currently available owing to the introduction of direct oral anticoagulants. The current VTE treatment recommendation is based on evidence from previous studies, but it should be applied with careful consideration of the racial, genetic, and social characteristics in the Korean population.

Hemostasis Laboratory Diagnostics: Characteristics, Communication Issues, and Current Challenges Resulting from Centralization of Laboratory Medicine

Laboratory diagnostics of patients with bleeding and thrombotic disorders can be a delicate task, which requires special skills and expertise. In this article, characteristic features of hemostasis testing are reviewed, including staged protocols and synoptic assessment of the patient history, clinical symptoms, and laboratory findings. Despite major progress in the diagnostic and therapeutic management, centralized testing of hemostasis can be associated with substantial challenges, resulting from the current dissociation between the clinical and laboratory world. To address some of these challenges, possible solutions are discussed, including adaptation of an established working paradigm.

Abnormal red blood cell indices increase the risk of arterial ischemic stroke in children

A high red cell distribution width (RDW) and low hemoglobin level increase the risk of arterial ischemic stroke (AIS), mostly in adults. The mechanisms related to AIS remain unknown. A total of 233 subjects (90 patients and 143 healthy controls [HC]) were enrolled. The mean(SD) age in patients and HC was 9.5(3.8) and 11.4(1.8) years, respectively. We found increased odds ratios (ORs) for large vessel and small vessel subtypes in patients without underlying diseases with a mean corpuscular volume (MCV) <80 fL (OR: 5.4, 95%CI 1.8-16.3 and 2.8, 95%CI 1.2-7.2), mean corpuscular hemoglobin levels <27 pg (OR: 2.9, 95%CI 1.0-6.7 and 2.6, 95%CI 1.0-6.7), and RDW >15% (OR: 5.5, 95%CI 1.3-24.5 and 2.7, 95%CI 1.0-7.3). RBC indices showed significant correlations with TM levels. Therefore, low MCV and MCH levels, and a high RDW were risk factors for AIS and associated with TM levels in this population.

A clinical audit of thrombophilia testing in pediatric patients with acute thromboembolic events: impact on management

Routine testing for inherited and acquired thrombophilia defects is frequently performed in pediatric patients with thromboembolic events (TEEs). No consensus guidelines exist regarding the timing of testing or the type of patients to be tested. The primary objective of our study, therefore, was to determine whether thrombophilia testing during the acute TEE setting affected clinical management in pediatric patients. A secondary aim included estimation of potential harm from thrombophilia testing. We retrospectively reviewed data on all pediatric patients diagnosed with a TEE during a 1-year period. Fifty-two (51%) of 102 patients with a TEE underwent thrombophilia testing during the acute phase, with 26 patients (50%) having a positive test result during the acute phase. Only 12% of patients tested were confirmed to have a thrombophilia eventually, yielding a false-positive rate of ∼7% for testing when performed in the acute setting. There were no changes to the acute management, regardless of a positive or negative result. Testing resulted in unnecessary blood loss in 12 patients younger than 1 year and acute testing cost approximately $82 000. Our data show that thrombophilia testing during acute TEEs in pediatric patients did not impact clinical management. There is also a potential for false-positive tests leading to unnecessary long-term anticoagulation. These findings suggest against thrombophilia testing during acute TEE setting in children.

Arterial Ischemic Stroke in Children and Young Adults

PURPOSE OF REVIEW

This article reviews risk factors, recurrence risk, evaluation, management, and outcomes of arterial ischemic stroke in children and young adults.

RECENT FINDINGS

The risk for recurrence and mortality appear to be low for neonatal and childhood stroke. Most children have relatively mild deficits, but those who have greater neurologic deficits, poststroke epilepsy, or strokes early in life are at risk for lower overall cognitive function. Stroke recurrence and long-term mortality after stroke in young adults are greater than originally thought. Cognitive impairments, depression, and anxiety are associated with higher levels of poststroke unemployment and represent targets for improved poststroke care. Poststroke care in young adults involves more than medical management. Self-reported memory and executive function impairments may be more severe than what is detected by objective measures. Assessment of possible cognitive impairments and appropriate management of psychological comorbidities are key to maximizing the long-term functional outcome of stroke survivors.

SUMMARY

Childhood and young adult stroke survivors survive for many more years than older patients with stroke. To ensure that these survivors maximize the productivity of their lives, neurologists must not only optimize medical management but also recognize that impairments in cognition and mood may be remediable barriers to long-term functional independence.

Pulmonary Embolism in Children

Pulmonary embolism (PE) in the pediatric population is relatively rare when compared to adults; however, the incidence is increasing and accurate and timely diagnosis is critical. A high clinical index of suspicion is warranted as PE often goes unrecognized among children leading to misdiagnosis and potentially increased morbidity and mortality. Evidence-based guidelines for the diagnosis, management, and follow-up of children with PE are lacking and current practices are extrapolated from adult data. Treatment options include thrombolysis and anticoagulation with heparins and oral vitamin K antagonists, with newer direct oral anticoagulants currently in clinical trials. Long-term sequelae of PE, although studied in adults, are vastly unknown among children and adolescents. Additional research is needed in order to provide pediatric focused care for patients with acute PE.

Thromboelastogram as a Tool to Predict Hypercoagulability in Children With Cystic Fibrosis

Increased thrombophilic tendency in patients with cystic fibrosis (CF) has recently been reported. The determinants of thrombosis in children with CF remain largely unknown. Our aim in this study was to evaluate the thromboelastography (TEG) profile of children with CF through ROTEM (whole blood rotation thromboelastometry). Nineteen patients with CF and 20 controls were included in the study. Whole blood count, prothrombin time, activated prothrombin time, fibrinogen, d-dimer levels, and ROTEM assays (INTEM, EXTEM) were performed. Clotting time, clot formation time (CFT), and maximum clot firmness (MCF) were determined by INTEM and EXTEM analysis. In INTEM assay, MCF ( P = .001) value was significantly increased and CFT ( P = .031) value was decreased in patients with CF compared with those of the control group. In the EXTEM assay, there was a similar significant increase in MCF ( P = .023) value in patients with CF compared with that of the control group. There was a significant positive correlation between fibrinogen levels and MCF in EXTEM ( r = .72) and INTEM ( r = .76) assays, whereas there was a negative correlation with CFT in EXTEM ( r = -.61) and INTEM ( r = -.67). The results of our study indicated that TEG profiles in patients with CF were more hypercoagulable compared with those of the control group.

Renal vascular thrombosis in the newborn

Neonatal renal vascular thrombosis is rare but has devastating sequelae. The renal vein is more commonly affected than the renal artery. Most neonates with renal vein thrombosis present with at least one of the three cardinal signs, namely, abdominal mass, macroscopic hematuria and thrombocytopenia, while unilateral renal artery thrombosis presents with transient hypertension. Contrast angiography is the gold standard for diagnosis but because of exposure to radiation and contrast agents, Doppler ultrasound scan is widely used instead. Baseline laboratory tests for platelet count, prothrombin time, activated partial thromboplastin time and fibrinogen concentration are essential before therapy is initiated. Maternal blood is tested for lupus anticoagulant and anticardiolipin antibody. Evaluation for prothrombotic disorders is warranted when thrombosis is clinically significant, recurrent or spontaneous. Management should involve a multidisciplinary team that includes neonatologists, radiologists, pediatric hematologists and nephrologists. In addition to supportive therapy, recent guidelines recommend at least prophylactic heparin therapy in the majority of cases to prevent thrombus extension. Thrombolytic therapy is reserved for bilateral thrombosis compromising kidney function. Long-term sequelae, such as kidney atrophy, systemic hypertension and chronic kidney disease, are common, and follow-up by pediatric nephrologists is recommended for monitoring of kidney function, early detection and management of hypertension and chronic kidney disease.

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.

Venous Thromboembolism in Adolescents

The incidence of venous thromboembolism (VTE) during childhood is low with two peaks – neonatal and adolescent age. This retrospective study is focused on clinical characteristics of VTE during adolescence. The main goals are to assess the most frequent inherited and acquired risk factors and to evaluate the benefit of D-dimers in diagnostics of venous thromboemblism. The data of 18 adolescents were analysed – 16 girls (88.9%), 2 boys (11.1%). In 9 patients (50%) thrombosis of the lower limb deep veins was diagnosed, six patients (33.3%) suffered from symptomatic pulmonary embolism (PE) and 3 patients (16.7%) from thrombosis at unusual sites. One patient had an idiopathic VTE, the mean number of the inherited and acquired risk factors was 2.6. The most frequent inherited risk factor was Leiden mutation of factor V (27.8%). The most frequent acquired risk factor was oral contraception (OC) in 12 out of 16 girls (75%). All of our patients on oral contraception had one or more additional risk factors. 10 out of 18 (55.6%) patients with VTE had elevated activity of factor VIII. The sensitivity of D-dimers was low (50%) in patients with distal lower limb thrombosis, but very high (100%) in patients with PE.

Thrombophilia testing in a tertiary paediatric hospital: Indications, outcomes and appropriateness

AIM

The association between inherited thrombophilia and thrombotic disease in children is unclear. As a result, whether expensive thrombophilia tests are indicated in children is a contentious issue. This retrospective study aimed to assess the appropriateness of thrombophilia testing and the associated cost of inappropriate testing at a tertiary paediatric hospital.

METHODS

We conducted a search for thrombophilia tests ordered at the Royal Children's Hospital between 1 January 2011 and 31 December 2013. Using pathology and clinical records, we collected data relating to demographics, clinical data, indications, requesting departments and impact on patient management.

RESULTS

Over the 3-year period, 3867 tests were ordered for 613 patients costing the hospital $102 579. Tests were most commonly ordered by gastroenterology on patients receiving liver transplants, by neurology as part of the stroke protocol, and by cardiology and cardiac surgery for patients anticoagulated on heparin infusions. Testing for thrombosis-related indications was relatively uncommon. Thrombophilia testing only directly affected management in one-third of patients. Overall, 70% of thrombophilia tests ordered were considered appropriate. However, some departments were found to have rates of inappropriate testing in excess of 50%.

CONCLUSION

With improvements in thrombophilia testing practices at the Royal Children's Hospital AU$29 645.40 could be saved over 3 years. While there are improvements to be made in this area, in the overall context of the hospital's pathology testing budget, review of other areas such as inappropriate use of low-cost, high-volume tests may be of greater value in reducing the cost of pathology testing.

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.

Global fibrinolytic activity, PAI-1 level, and 4G/5G polymorphism in Thai children with arterial ischemic stroke

BACKGROUND

Prolonged euglobulin clot lysis time (ECLT) and increased level of plasminogen activator inhibitor-1 (PAI-1) were reported to be risk factors of arterial ischemic stroke (AIS) by some studies; however, these findings were not supported by other studies. The objective of this study was to determine the association of ECLT, PAI-1 level, and polymorphisms of 4G and 5G of PAI-1 gene to the development of AIS in Thai children.

METHODS

This study included patients aged 1-18 years old. Diagnosis of AIS was confirmed by imaging study. The control group was age- and sex-matched healthy subjects. Demographic data were recorded, and blood was tested for ECLT, PAI-1 level, lipid profiles, fasting blood sugar (FBS), and 4G and 5G polymorphisms of PAI-1 gene.

RESULTS

There were 70 subjects participating in this study, consisting of 30 patients and 40 controls. Demographic data, lipid profiles, and FBS were similar between the 2 groups. Furthermore, ECLT and PAI-1 level did not differ between patient and control groups; however, both showed significant correlation (r = .352, P = .006). The 4G/5G polymorphism was the most common genotype in both patient and control groups (69.0% vs. 80.0%). However, 4G and 5G polymorphisms of PAI-1 gene did not correlate with PAI-1 level in this study (P = .797).

CONCLUSIONS

The PAI-1 level and 4G/5G polymorphism may not be a risk factor of AIS in this population. It was also found that the 4G/5G polymorphism was the most common PAI-1 genotype in this study.

[Deep venous thrombosis complications during infections in pediatric patients: analysis of a series of 24 cases]

Venous thromboembolism disease (VTE) is rare in children (5.3 of 10,000 hospitalized children). However, morbidity and mortality are high, especially when the child is already suffering from severe sepsis. We report an analytical study of 24 cases of deep venous thrombosis occurring in children during infection, recorded at the Montpellier University Hospital between 1999 and 2009. Many parameters were studied in each population (age, sex, familial and personal history of thrombosis, history of thrombophilia, the presence of a venous catheter, a causative organism, time to onset of thrombus, topography of lesions, acquired abnormalities of hemostasis, and thrombosis prophylaxis). The children were aged from 1 day of life to 16 years. Thromboses occurred in two clinical contexts: "contact" thrombosis (which appeared near the infection) and disseminated thrombosis. This is an early complication because in most of the cases, it appeared in the first 10 days of sepsis. Infection and coagulation appear to be closely related and the states of latent or decompensated disseminated intravascular coagulation are common. Nevertheless, it is not possible to predict the occurence of a thrombotic event. The presence of risk factors (venous catheters, acquired thrombophilia, or constitutional thrombophilia) may increase the thrombogenic potential of the infection. VTE should always be suspected and sought in case of an unfavorable clinical course, and routine prophylaxis of thrombosis during sepsis should be discussed.

Pediatric thrombophilia

Pediatric thrombosis and thrombophilia are increasingly recognized and studied. In this article, both the inherited and acquired factors for the development of thrombosis in neonates and children are categorized using the elements of Virchow's triad: stasis, hypercoagulable state, and vascular injury. The indications and rationale for performing thrombophilia testing are described. Also included are discussions on who, how, when, and why to test. Finally, recommendations for the use of contraceptives for adolescent females with a family history of thrombosis are outlined.

Arteriopathy, D-dimer, and risk of poor neurologic outcome in childhood-onset arterial ischemic stroke

OBJECTIVE

To assess whether acute findings of cerebral arteriopathy, large infarct, and acutely elevated plasma D-dimer levels are independently prognostic of poor long-term neurologic outcome as measured at ≥ 1 year post-event in children with arterial ischemic stroke (AIS).

STUDY DESIGN

Sixty-one patients with childhood-onset (ie, >28 days of life) AIS were enrolled in a single-institution cohort study at Children's Hospital Colorado between February 2006 and June 2011. Data on demographic and diagnostic characteristics, antithrombotic treatments, and outcomes were systematically collected.

RESULTS

Cerebral arteriopathy and D-dimer levels >500 ng/mL (a measure of coagulation activation) were identified acutely in 41% and 31% of the cohort, respectively. Anticoagulation was administered in the acute period post-event in 40% of the children, in the subacute period in 43%, and in the chronic period in 28%. When not receiving anticoagulation, patients were routinely treated with aspirin 2-5 mg/kg once daily for a minimum of 1 year. Death, major bleeding (including intracranial hemorrhage), and recurrent AIS were infrequent. The Pediatric Stroke Outcome Measure at 1 year demonstrated poor outcome in 54% of the children. Acute cerebral arteriopathy and elevated D-dimer level were identified as putative prognostic factors for poor outcome; after adjustment for D-dimer, arteriopathy was an independent prognostic indicator (OR, 19.0; 95% CI, 1.6-229.8; P = .02).

CONCLUSION

Arteriopathy and coagulation activation are highly prevalent in the acute period of childhood AIS. Although recurrent AIS and intracranial hemorrhage were infrequent in our cohort, one-half of children experienced a poor neurologic outcome at 1 year, the risk of which was increased by acute arteriopathy. Substantiation of these findings in multi-institutional cohort studies is warranted, toward risk stratification in childhood-onset AIS.

Subclavian vein thrombosis after application of body cast

Mehta-Cotrel body casting is a well-recognized and effective technique for the treatment of progressive infantile scoliosis. The treatment can be challenging to execute given the commitment required by the patient's family and treatment team, and is not without complications. In this report, we detail the occurrence of a subclavian vein thrombosis after the placement of a Mehta-Cotrel cast for the treatment of progressive infantile kyphoscoliosis. To date, this is a previously unreported complication after body casting. Expeditious and accurate diagnosis of this complication leads to effective treatment without further morbidity. Therefore, clinicians using body casting for the treatment of scoliosis should be aware of the possibility of this complication and know how to quickly diagnose and treat it.

Evaluation of the presence of hereditary and acquired thrombophilias in Brazilian children and adolescents with diagnoses of portal vein thrombosis

OBJECTIVE

The aim of this study was to describe the prevalence of main hereditary thrombophilias, Janus kinase 2 (JAK2) V617F mutation, antiphospholipid antibody syndrome (APS), and hyperhomocysteinemia in Brazilian children and adolescents diagnosed with portal vein thrombosis (PVT) without associated hepatic disease.

METHODS

A cross-sectional study was carried out with 32 children with PVT in accompaniment at Hospital das Clínicas of the Universidade Federal de Minas Gerais from January 1990 to July 2011. Laboratory evaluation of thrombophilias was performed from September 2010 to July 2011.

RESULTS

Thirty-two patients were evaluated; 59% were boys. Median age at diagnosis was 2.4 years. Mean time of patients' accompaniment was between 4.7 and 5.2 years. The presence of hereditary and acquired thrombophilias occurred in 34.4% of patients, and 9 of them also showed other risk factors in the previous history evaluation. Risk factors were absent in the previous history of 18 patients (56.3%). Two patients showed persistent high titres of anticardiolipin antibodies. Hyperhomocysteinemia was not observed. One patient was heterozygous for factor V Leiden and prothrombin G20210A mutation (3.1%). Eleven patients (34.4%) showed heterozygous methylenetetrahydrofolate reductase (MTHFR) C677T, and no patient had the JAK2V617F mutation.

CONCLUSIONS

Even after investigation of main hereditary and acquired thrombophilia, PVT remains without apparent cause in most patients. Nevertheless, association of local and systemic risk factors seems to be important also in the pediatric age group. Therefore, despite the low prevalence, a complete investigation, which includes both hereditary and acquired thrombophilias, may be necessary.

Treatment, survival, and thromboembolic outcomes of thrombotic storm in children

OBJECTIVE

To describe the course and management of thrombotic storm in 8 children.

STUDY DESIGN

Clinical data were collected and analyzed for consecutive children diagnosed with thrombotic storm, aged 6 months to 21 years inclusive, in the context of a single-institution prospective inception cohort study. Thrombotic storm was defined as newly diagnosed multisite venous thromboembolism (VTE) with acute thrombus progression despite conventional or higher than conventional dosing of heparin or low molecular weight heparin. All evaluations and therapies were ordered by the treating physicians in the context of clinical decision making.

RESULTS

Eight of the 178 children with VTE enrolled in the cohort between March 2006 and November 2009 were diagnosed with thrombotic storm. Antiphospholipid antibodies were acutely positive in 6 children, of whom heparin-induced thrombocytopenia was confirmed by serotonin release assay in 2 and atypical in 1. One child died. Five children received a direct thrombin inhibitor, titrated to achieve normalization of markedly elevated D-dimer levels. All children were transitioned to fondaparinux or enoxaparin before receiving extended anticoagulation with warfarin. Immunomodulatory therapy was instituted in all children. During follow-up (median duration, 3 years; range, 2-6 years), 3 of the 7 surviving children experienced recurrent VTE, and 4 children had clinically significant postthrombotic syndrome.

CONCLUSION

Thrombotic storm is an infrequent but potentially fatal presentation of VTE in children. Administration of direct thrombin inhibitors and immune modulation can achieve quiescence, although long-term adverse outcomes are common.

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.

Factor V Leiden thrombophilia

Factor V Leiden is a genetic disorder characterized by a poor anticoagulant response to activated Protein C and an increased risk for venous thromboembolism. Deep venous thrombosis and pulmonary embolism are the most common manifestations, but thrombosis in unusual locations also occurs. The current evidence suggests that the mutation has at most a modest effect on recurrence risk after initial treatment of a first venous thromboembolism. Factor V Leiden is also associated with a 2- to 3-fold increased relative risk for pregnancy loss and possibly other obstetric complications, although the probability of a successful pregnancy outcome is high. The clinical expression of Factor V Leiden is influenced by the number of Factor V Leiden alleles, coexisting genetic and acquired thrombophilic disorders, and circumstantial risk factors. Diagnosis requires the activated Protein C resistance assay (a coagulation screening test) or DNA analysis of the F5 gene, which encodes the Factor V protein. The first acute thrombosis is treated according to standard guidelines. Decisions regarding the optimal duration of anticoagulation are based on an individualized assessment of the risks for venous thromboembolism recurrence and anticoagulant-related bleeding. In the absence of a history of thrombosis, long-term anticoagulation is not routinely recommended for asymptomatic Factor V Leiden heterozygotes, although prophylactic anticoagulation may be considered in high-risk clinical settings. In the absence of evidence that early diagnosis reduces morbidity or mortality, decisions regarding testing at-risk family members should be made on an individual basis.

Percutaneous mechanical and pharmacomechanical thrombolysis for occlusive deep vein thrombosis of the proximal limb in adolescent subjects: findings from an institution-based prospective inception cohort study of pediatric venous thromboembolism

PURPOSE

Young individuals with occlusive, proximal-limb deep vein thrombosis (DVT) who have acutely increased plasma levels of factor VIII and D-dimer are at high risk for postthrombotic syndrome (PTS) when treated with conventional anticoagulation alone. The present report is an evaluation of experience with adjunctive percutaneous mechanical thrombolysis (PMT) and/or percutaneous pharmacomechanical thrombolysis (PPMT) in such patients.

PATIENTS AND METHODS

Among 95 children 11-21 years of age enrolled in a prospective cohort of venous thromboembolism between March 1, 2006, and November 1, 2009, 16 met eligibility criteria and underwent PMT/PPMT, typically with adjunctive catheter-directed thrombolytic infusion (CDTI) of tissue-type plasminogen activator given after the procedure.

RESULTS

Median age was 16 years (range, 11-19 y). Thirteen cases (81%) involved lower limbs. Underlying stenotic lesions were disclosed in 53%, with endovascular stents deployed in all cases of May-Thurner anomaly. There were no periprocedural major bleeding events and one symptomatic pulmonary embolism. Technical success rate was 94%. Early (< 30 days) locally recurrent DVT developed in 40% of cases, of which 83% were successfully treated with repeat lysis. Late recurrent DVT rate (median follow-up duration, 14 months; range, 1-42 mo) was 27%. Cumulative incidence of physically and functionally significant PTS at 1-2 years was 13%.

CONCLUSIONS

This experience provides preliminary evidence that PMT/PPMT with adjunctive CDTI can be used safely and effectively in adolescent subjects with DVT at high risk for PTS.

Thrombotic disease in critically ill children

OBJECTIVES

To summarize a) epidemiology of arterial and venous thromboembolism, pulmonary embolism, and deep venous thrombosis in children; b) the risk factors for thrombosis in the pediatric intensive care unit; c) diagnostic techniques for arterial/venous thromboembolism; and d) the current recommendations for management and prevention of thromboembolic disease in critically ill children.

DATA SOURCE

Literature review, using National Library of Medicine PubMed and the following terms: arterial, venous thromboembolism; deep venous thrombosis; pulmonary embolism; thrombosis; as well as citations of interest from these articles.

STUDY SELECTION

Both pediatric and adult literature addressing thrombotic disease were reviewed.

DATA EXTRACTION AND SYNTHESIS

Articles were chosen for more extensive discussion when containing prospective studies, guidelines for practice, or data in critically ill patients. When data in children were unavailable, applicable data in adults were referenced. Due to the paucity of data in critically ill children, available adult and pediatric data were combined with institutional experience to provide suggestions for current practice and future inquiry.

CONCLUSIONS

Increasing awareness regarding the recognition and current approaches to management and prevention of thromboembolic disease in children is needed among pediatric intensivists, so outcome of these life-threatening processes might be improved.

The roles of anatomic factors, thrombophilia, and antithrombotic therapies in childhood-onset arterial ischemic stroke

Childhood-onset arterial ischemic stroke (AIS) is a rare disorder with high risks of both recurrent stroke and life-long neurological morbidity. Anatomic risk factors for primary and/or recurrent AIS include a venous thrombotic source for paradoxical embolism via a patent foramen ovale, primary cardioembolism, extracranial dissection, and intracranial arteriopathies, among others. Genetic and acquired thrombophilias are common, some of which have been shown to have prognostic influence on risk of recurrent AIS. While knowledge of childhood AIS risk factors has grown considerably in recent years, an evidence-based understanding of optimal antithrombotic therapy strategies has not yet been attained. Consensus-based guidelines have been developed, but future research must emphasize identification of additional prognostic factors and the initiation of cooperative randomized controlled clinical trials.

Thrombophilia screening--at the right time, for the right patient, with a good reason

Thrombophilia can be identified in about half of all patients presenting with venous thromboembolism (VTE). Thrombophilia screening for various indications has increased tremendously, but whether the results of such tests help in the clinical management of patients is uncertain. Here, current recommendations for thrombophilia screening in selected groups of patients, and considerations whether other high-risk subjects should be tested are reviewed. The methods for determination of the most common thrombophilic defects (antithrombin, protein C, protein S deficiencies, Factor V Leiden and prothrombin G20210A) associated with strong to moderate risk of VTE are described, indicating the timing and location of thrombophilia screening. Circumstances when a positive result of thrombophilia screening helps clinicians decide if adjustments of the anticoagulant regime are needed are discussed. Finally, psychological, social and ethical dilemmas associated with thrombophilia screening are indicated.

Pediatric stroke: the importance of cerebral arteriopathy and vascular malformations

PURPOSE

Population-based estimates of the annual incidence of childhood stroke range from 2 to 13 per 100,000 person-years. More than half of children who have had a stroke have long-term neurological sequelae. The goal of this article is to review recent literature on both hemorrhagic and ischemic stroke in children with a focus on cerebral arteriopathy and vascular malformations as stroke risk factors. Additionally, we review diagnostic studies for childhood stroke, outcome data, and regional and geographic practice differences.

METHODS

PubMed was searched using the terms child, childhood, pediatric, stroke, ischemic, intracerebral hemorrhage, vasculopathy, and vascular malformation. Reference lists of these articles were reviewed for additional key publications. Preference was given to articles published since the year 2000; however, seminal articles in the field were also reviewed.

RESULTS

Pediatric stroke is a heterogeneous disorder and a major cause of morbidity in the pediatric population. Five-year recurrence risk is estimated to be 5-19%. Children with cerebrovascular abnormalities are at the highest risk of recurrence (66% at 5 years for ischemic stroke in one study). Furthermore, cerebral arteriopathy including arterial dissection may account for up to 80% of childhood stroke in otherwise healthy children.

CONCLUSION

In many cases, evaluation and treatment of pediatric stroke is not evidence-based, and regional and geographic variations in practice patterns exist. Ultimately multicenter cohort studies and dedicated pediatric clinical trials are essential to establish comprehensive evidence-based guidelines for pediatric stroke care.

Testing children for inherited thrombophilia: more questions than answers

Thrombotic events in children have become an increasingly common problem, particularly in paediatric tertiary care hospitals. The prevalence of inherited thrombophilia in children who develop thrombosis varies substantially depending on the population. Children who develop thrombosis, as well as those who have not but have a positive family history, are frequently tested for inherited thrombophilia. The clinical utility of performing such tests has been questioned, in both adults and children. This review will examine the practise of testing for inherited thrombophilia in children, focusing on the rationale for testing and highlighting areas in which more evidence is needed prior to making strong recommendations. Future studies, many of which are currently being performed or proposed, are necessary to address many of the unanswered questions.

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.

Using thrombophilia testing to determine anticoagulation duration in pediatric thrombosis is not cost-effective

OBJECTIVE

To address the cost-effectiveness of thrombophilia testing and treatment strategies among children with a first episode of thrombosis.

STUDY DESIGN

A 2-year Markov model was developed to evaluate the cost-utility of 3 strategies: (1) no testing, anticoagulate for 3 months, (2) no testing, anticoagulate for 6 months, and (3) testing, anticoagulate 3 or 6 months, based on results. We performed a literature search to estimate clinical probabilities and obtained quality-of-life and cost data from published sources.

RESULTS

Total costs per patient were $7900 for no test, treat for 3 months; $8900 for test, treat based on results; and $12,100 for no test, treat for 6 months. Three months of treatment without testing was the least expensive strategy and also the most effective (1.74 quality-adjusted life-years) by 0.01 to 0.03 quality-adjusted life-years. Cost-utility ratios were sensitive to variation in hospitalization and medication costs, but 3 months, no testing, always remained the preferred choice.

CONCLUSIONS

Universal thrombophilia testing after a first episode of thrombosis is not cost-effective when used solely to determine anticoagulation duration. Therefore, a full panel of thrombophilia studies does not need to be an automatic response at the time of any deep venous thrombosis diagnoses.

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.

Elevated maternal lipoprotein (a) and neonatal renal vein thrombosis: a case report

INTRODUCTION

Renal vein thrombosis, although rare in adults, is well recognized in neonates and is one of the most common manifestations of neonatal thromboembolic events. The etiology of renal vein thrombosis remains unidentified in the majority of cases. We report a case of renal vein thrombosis in a neonate associated with elevated maternal lipoprotein (a).

CASE PRESENTATION

A full-term female infant, appropriate for gestational age, was born via spontaneous vaginal delivery to an 18-year-old primigravida. The infant's birth weight was 3680 g and the Apgar scores were eight and nine at 1 and 5 minutes respectively. Evaluation of the infant in the newborn nursery revealed a palpable mass in the right lumbar area. Tests revealed hematuria and a high serum creatinine level of 1.5 mg/dl. An abdominal ultrasound Doppler flow study demonstrated an enlarged right kidney, right renal vein thrombosis, and progression of the thrombosis to the inferior vena cava. There was no evidence of saggital sinus thrombosis. An extensive work-up of parents for hypercoagulable conditions was remarkable for a higher plasma lipoprotein (a) level of 73 mg/dl and an elevated fibrinogen level of 512 mg/dl in the mother. All paternal levels were normal. The plasma lipoprotein (a) level in the neonate was also normal. The neonate was treated with low molecular weight heparin (enoxaparin) at 1.5 mg/kg/day every 12 hours for 2 months, at which time a follow-up ultrasound Doppler flow study showed resolution of the thrombosis in both the renal vein and the inferior vena cava.

CONCLUSION

There have been no studies to date that have explored the effect of abnormal maternal risk factors on fetal hemostasis. A case-control study is required to investigate whether elevated levels of maternal lipoprotein (a) may be a risk factor for neonatal thrombotic processes. Although infants with this presentation are typically treated with anticoagulation, there is a lack of evidence-based guidelines. Treatment modalities vary between study and treatment centers which warrants the establishment of a national registry.

Venous thromboembolism in children

With improved pediatric survival from serious underlying illnesses, greater use of invasive vascular procedures and devices, and a growing awareness that vascular events occur among the young, venous thromboembolism (VTE) increasingly is recognized as a critical pediatric concern. This review provides background on etiology and epidemiology in this disorder, followed by an in-depth discussion of approaches to the clinical characterization, diagnostic evaluation, and management of pediatric VTE. Prognostic indicators and long-term outcomes are considered, with emphasis on available evidence underlying current knowledge and key questions for further investigation.

Thrombophilia in Children: Who to Test, How, When, and Why?

Thrombosis and thrombotic risk factors in children are receiving increased attention, and pediatric hematologists frequently are asked to evaluate children with symptomatic thrombosis, or asymptomatic children who have relatives affected with either thrombosis or thrombophilia. The clinical utility of thrombophilia testing has become increasingly debated, both in adults and children. Children with thrombosis are a heterogeneous group, and it is unlikely that a single approach to testing or treatment is optimal or desirable. A causative role of inherited prothrombotic defects in many pediatric thrombotic events, particularly catheter-related thrombosis, has not been established. Pediatric patients most likely to benefit from thrombophilia testing include adolescents with spontaneous thrombosis and teenage females with a known positive family history who are making choices about contraception. Recent data suggest that some inherited thrombophilic defects are associated with a higher risk of recurrent venous thromboembolism in children, though optimal management of these patients has yet to be determined. The decision to perform thrombophilia testing in asymptomatic patients with a family history should be made on an individual basis after discussion with the family. Given that the field of pediatric thrombosis continues to evolve, and the settings in which many of these events occur are unique to childhood, prospective longitudinal analyses of such patients to determine outcome and response to treatment as well as the impact of known thrombophilic states on these outcomes are clearly needed.

Venous thromboembolism in the neonatal period

Thromboembolism occurs more frequently in newborns than in older infants or children. The developing hemostasis system of neonates has decreased concentrations of procoagulant proteins and the naturally occurring anticoagulants and hemostatic control proteins. Overall, neonatal hemostasis provides protection from excessive bleeding at the expense of an increased risk for thromboembolism. Intensive medical care for premature and ill infants often requires central vascular assess, and the most frequent risk factor for thromboembolism is the presence of an indwelling vascular catheter. Management of venous thromboembolism in the newborn period varies depending on the location and extent of the thrombus as well as the risk for acute embolic complications and later vascular compromise. Therapeutic decisions are guided by practitioners' past experience, published case reports and case series, several large registries, and extrapolation from results of clinical trials in adults with thromboembolic disease. Valuable consensus guidelines have been compiled by the AACP Conference on Antithrombotic and Thrombolytic Therapy. Heparin, either unfractionated or a low molecular weight preparation, is the most commonly utilized anticoagulant to treat thromboembolism in newborn infants. Thrombolytic therapy may be considered if the thrombus is life or limb threatening and there is no hemorrhagic contraindication. Multicenter, prospective, controlled clinical trials in this important patient population are needed to provide evidence-based data to better inform optimal management.

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.

A thrombolytic regimen for high-risk deep venous thrombosis may substantially reduce the risk of postthrombotic syndrome in children

Important predictors of adverse outcomes of thrombosis in children, including postthrombotic syndrome (PTS), have recently been identified. Given this knowledge and the encouraging preliminary pediatric experience with systemic thrombolysis, we sought to retrospectively analyze our institutional experience with a thrombolytic regimen versus standard anticoagulation for acute, occlusive deep venous thrombosis (DVT) of the proximal lower extremities in children in whom plasma factor VIII activity and/or D-dimer concentration were elevated at diagnosis, from within a longitudinal pediatric cohort. Nine children who underwent the thrombolytic regimen and 13 who received standard anticoagulation alone were followed from time of diagnosis with serial clinical evaluation and standardized PTS outcome assessments conducted in uniform fashion. The thrombolytic regimen was associated with a markedly decreased odds of PTS at 18 to 24 months compared with standard anticoagulation alone, which persisted after adjustment for significant covariates of age and lag time to therapy (odds ratio [OR] = 0.018, 95% confidence interval [CI] = < 0.001-0.483; P = .02). Major bleeding developed in 1 child, clinically judged as not directly related to thrombolysis for DVT. These findings suggest that the use of a thrombolysis regimen may safely and substantially reduce the risk of PTS in children with occlusive lower-extremity acute DVT, providing the basis for a future clinical trial.

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.