Impact of Inherited Thrombophilia on Venous Thromboembolism in Children

Thrombosis in Children: A Retrospective Study from a Single-center Database

BACKGROUND/AIM

The incidence and characteristics of pediatric thrombotic events have become increasingly recognized, due to the enhanced utilization of advanced diagnostic techniques. Pediatric thrombosis remains less frequent than in adults, often manifesting in those with underlying congenital or acquired risk factors. This study aimed to establish epidemiological data on pediatric thrombotic events in Bihor County, Romania, highlighting the challenges of diagnosis in smaller medical centers and proposing a relevant diagnostic and treatment algorithm.

PATIENTS AND METHODS

This retrospective study, conducted over 22 years at the Emergency County Clinical Hospital Bihor, identified 39 pediatric patients diagnosed with thrombotic events using electronic medical records.

RESULTS

Most patients (82.1%) were diagnosed between 2013 and 2024, with a slight male predominance. The age distribution shows two peak clusters: newborns up to one year and adolescents. The majority of cases (53.8%) were venous thromboembolism, followed by arterial thromboembolism at 41%, while 5.1% involved both types. Cerebral thrombosis was the most common, followed by lower and upper limb events. Inherited thrombophilia factors were found in all patients tested, with antithrombin, protein S, and protein C deficiencies identified. Malignancy was the most frequently acquired risk factor, and PAI-1 4G/5G was the most common genetic variant detected among inherited factors.

CONCLUSION

This study highlights the significant rise in pediatric thromboembolism recognition over the past two decades; however, underdiagnosis remains an issue. Improved awareness among healthcare professionals is crucial, particularly for unprovoked thrombosis cases where a thorough thrombophilia panel and the involvement of a multidisciplinary team may be necessary.

Venous valve hypoxia as a possible mechanism of deep vein thrombosis: a scoping review

INTRODUCTION

The pathogenesis of deep vein thrombosis (DVT) has been explained by an interplay between a changed blood composition, vein wall alteration, and blood flow abnormalities. A comprehensive investigation of these components of DVT pathogenesis has substantially promoted our understanding of thrombogenesis in the venous system. Meanwhile, the process of DVT initiation remains obscure. This systematic review aims to collect, analyze, and synthesize the published evidence to propose hypoxia as a possible trigger of DVT.

EVIDENCE ACQUISITION

An exhaustive literature search was conducted across multiple electronic databased including PubMed, EMBASE, Scopus, and Web of Science to identify studies pertinent to the research hypothesis. The search was aimed at exploring the connection between hypoxia, reoxygenation, and the initiation of deep vein thrombosis (DVT). The following key words were used: "deep vein thrombosis," "venous thrombosis," "venous thromboembolism," "hypoxia," "reoxygenation," "venous valve," and "venous endothelium." Reviews, case reports, editorials, and letters were excluded.

EVIDENCE SYNTHESIS

Based on the systematic search outcome, 156 original papers relevant to the issue were selected for detailed review. These studies encompassed a range of experimental and observational clinical research, focusing on various aspects of DVT, including the anatomical, physiological, and cellular bases of the disease. A number of studies suggested limitations in the traditional understanding of Virchow's triad as an acceptable explanation for DVT initiation. Emerging evidence points to more complex interactions and additional factors that may be critical in the early stages of thrombogenesis. The role of venous valves has been recognized but remains underappreciated, with several studies indicating that these sites may act as primary loci for thrombus formation. A collection of studies describes the effects of hypoxia on venous endothelial cells at the cellular and molecular levels. Hypoxia influences several pathways that regulate endothelial cell permeability, inflammatory response, and procoagulation activity, underpinning the endothelial dysfunction noted in DVT.

CONCLUSIONS

Hypoxia of the venous valve may serve as an independent hypothesis to outline the DVT triggering process. Further research projects in this field may discover new molecular pathways responsible for the disease and suggest new therapeutic targets.

The clinical and genetic landscape of early-onset thrombophilia in Japan

OBJECTIVES

To determine the optimal management for early-onset thrombophilia (EOT), the genetic and clinical features of protein C (PC)-, protein S (PS)-, or antithrombin (AT)-deficient patients of ≤20 years of age were studied in Japan.

METHODS/RESULTS

Clinical and genetic information of all genetically diagnosed cases was collected through the prospective, retrospective study, and literature review. One-hundred-one patients had PC (n = 55), PS (n = 29), or AT deficiency (n = 18). One overlapping case had PC- and PS-monoallelic variant. Fifty-five PC-deficient patients (54%) had 26 monoallelic or 29 biallelic variant(s), and 29 (29%) PS-deficient patients had 20 monoallelic or nine biallelic variant(s). None of the patients had AT-biallelic variants. The frequent low-risk allele p.K193del (PC-Tottori) was found in five patients with monoallelic (19%) but not 29 with biallelic variant(s). The most common low-risk allele p.K196E (PS-Tokushima) was found in five with monoallelic (25%) and six with biallelic variant(s) (67%). One exceptional de novo PC variant was found in 32 families with EOT. Only five parents had a history of thromboembolism. Thrombosis concurrently developed in three mother-newborn pairs (two PC deficiency and one AT deficiency). The prospective cohort revealed the outcomes of 35 patients: three deaths with PC deficiency and 20 complication-free survivors. Neurological complications were more frequently found in patients with PC-biallelic variants than those with PC-, PS-, or AT-monoallelic variants (73% vs. 24%, p = .019).

CONCLUSIONS

We demonstrate the need for elective screening for EOT targeting PC deficiency in Japan. Early prenatal diagnosis of PC deficiency in mother-infant pairs may prevent perinatal thrombosis in them.

The Effect of Serum Electrolyte Levels and Infusion Treatments on the Development of Femoral Central Venous Catheter-Associated Deep Vein Thrombosis in Pediatric Intensive Care Unit

In this study, we aimed to determine the frequency of symptomatic central venous catheters-associated deep vein thrombosis (CVC-a DVT) among critically ill children with femoral vein implantation in our pediatric intensive care unit (PICU), and to compare the demographic factors, serum electrolyte levels, and types of the infusion treatments performed. A total of 215 patients aged 1 month to 18 years who had femoral CVC implanted between 2019 and 2021 were included in this study. The cases that were clinically symptomatic and had thrombosis diagnosed ultrasonography were accepted as CVC-a DVT (+), and the other cases were considered as CVC-a DVT (-). Of the total 215 cases, 57.2% (n = 123) were female and 42.8% (n = 92) were male. Catheters-associated deep vein thrombosis diagnosis were made in 9.8% of the cases (n = 21). The mean time to diagnose thrombosis in CVC-a DVT (+) cases was 8.33 ± 5.65 days. With regard to gender, age, blood type, intubation status, length of stay on mechanical ventilator, presence of extra hemodialysis catheter, acute and chronic disease status, number of days of PICU hospitalization, and Pediatric Risk of Mortality-3 scoring, no significant differences between CVC-a DVT (-) and CVC-a DVT (+) cases were observed (P > .05). The incidence of thrombosis in refugee cases was found to be significantly higher than in Turkish cases (P = .047; P < .05). There was no statistically significant difference between the groups in baseline, mean, and peak glucose, sodium, and magnesium values and who received magnesium, blood product, inotrope, and 3% hypertonic saline (HTS) infusion (P > .05). No effect of serum glucose, sodium, and magnesium levels on the development of CVC-a DVT was found. Magnesium, blood product, inotrope, and 3% HTS infusion treatments have not been shown to have an effect on the development of CVC-a DVT.

Lipoprotein (a): Does It Play a Role in Pediatric Ischemic Stroke and Thrombosis?

PURPOSE OF REVIEW

The goal of this paper is to describe the current understanding of lipoprotein (a) (Lp(a)), clinical practice guidelines, and the potential pathophysiological mechanisms that appear to increase the risk of cardiovascular and thromboembolic events, specifically within the pediatric population.

RECENT FINDINGS

The proatherogenic and pro-thrombotic properties of Lp(a) may increase the risk of atherothrombotic disease. In adults, atherosclerotic plaques increase thrombotic risk, but antifibrinolytic and proinflammatory properties appear to have an important role in children. Although it is not well established in neonates, recent studies indicate the risk of incident thrombosis and ischemic stroke are approximately fourfold higher in children with elevated Lp(a) which also increases their risk of recurrent events. Despite this higher risk, Pediatric Lp(a) screening guidelines continue to vary among different medical societies and countries. The inconsistency is likely related to inconclusive evidence outside of observational studies and the lack of specific therapies for children with elevated levels. Additional research is needed to improve understanding of the pro-thrombotic mechanisms of Lp(a), appropriate screening guidelines for Lp(a) in the pediatric population, and to elucidate the short and long term effects of elevated Lp(a) on the risk of pediatric thrombosis and stroke.

Impact of SERPINC1 mutation on thrombotic phenotype in children with congenital antithrombin deficiency-first analysis of the International Society on Thrombosis and Haemostasis pediatric antithrombin deficiency database and biorepository

BACKGROUND

The natural history and genotype-phenotype correlation of congenital antithrombin (AT) deficiency in children are unknown.

OBJECTIVES

To describe the clinical presentation of congenital AT deficiency in children and evaluate its correlation to specific mutations in SERPINC1.

METHODS

In 2017, a prospective pediatric database and DNA biorepository for congenital AT deficiency was established. During the pilot phase, the database was opened at 4 tertiary care centers in Canada and US. Approval from research ethics board was obtained at each participating center. Written consent/assent was obtained from guardians/subjects who met eligibility. Demographic/clinical data were uploaded into a database. DNA extraction and SERPINC1 sequencing were centralized for US centers. Standard statistical methods were used to summarize parameters. Probability of VTE-free survival was assessed using the Kaplan-Meier method.

RESULTS

Overall, 43 participants (25 females) from 31 unique kindreds were enrolled. Median age (range) at enrollment was 14.8 years (1-21 years). Median AT activity was 52% (24%-87%), and median AT antigen (n = 20) was 55% (38%-110%). Nineteen (44%) participants had a history of venous thromboembolism (VTE). Median age at VTE diagnosis was 12.8 years (0.1-19.2 years). SERPINC1 sequencing was completed for 31 participants and 21 unique mutations were identified, including 5 novel variants. Probability of 5-year VTE-free survival (95% CI) for carriers of missense mutations (92.0% [95% CI: 71.6%-97.9%]) was significantly higher compared with carriers of null mutations (66.7% [95% CI: 19.5%-90.4%]); p = .0012.

CONCLUSION

To our knowledge, this is the first pediatric study to document a severe thrombotic phenotype in carriers of null mutations in SERPINC1, when compared with carriers of missense mutations; underscoring the importance of genetic testing.

50 Years of Pediatric Hemostasis: Knowledge, Diagnosis, and Treatment

Studies from the past 50 years have contributed to the expanding knowledge regarding developmental hemostasis. This is a dynamic process that begins in the fetal phase and is characterized by physiological variations in platelet counts and function, and concentrations of most coagulation factors and the native coagulation inhibitors in early life, as compared with adulthood. The developmental hemostasis studies since the 1980 to 1990s established the laboratory reference values for coagulation factors. It was only a decade or two later, that thromboelastography (TEG) or (rotational thromboelastometry [ROTEM]) as well as thrombin generation studies, provided special pediatric reference values along with the ability to evaluate clot formation and lysis. In addition, global whole blood-based clotting assays provided point of care guidance for proper transfusion support to children hospitalized in intensive care units or undergoing surgery. Although uncommon, thrombosis in children and neonates is gaining increasing recognition, typically as a secondary complication in sick children. Bleeding in children, and particularly intracerebral hemorrhage in newborns, still represent a therapeutic challenge. Notably, our review will outline the advancements in understanding developmental hemostasis and its manifestations, with respect to the pathophysiology of thrombosis and bleeding complications in young children. The changes of transfusion policy and approach to thrombophilia testing during the last decade will be mentioned. Subsequently, a brief summary of the data on anticoagulant treatments in pediatric patients will be presented. Finally, we will point out the 10 most cited articles in the field of pediatric and neonatal hemostasis.

The utility of risk assessment tools for acute pulmonary embolism in children

BACKGROUND AND AIM: Pulmonary embolism (PE) is a potentially life-threatening disease in children. The objective of the study is to evaluate the utility of adult-based pulmonary embolism rule-out criteria (PERC), Pediatric PE Model, and D-dimer in the diagnosis of PE in children.

MATERIAL AND METHODS

The study consisted of patients under 18 years of age who were consulted to the Pediatric Pulmonology Clinic for the evaluation of PE. Patients were divided into two groups based on the confirmation of PE. The group with the presence of PE (n = 20) consisted of children who were diagnosed with PE. The group with the absence of PE (n = 28) consisted of children with clinically suspected PE but negative diagnostic imaging. Adult validated clinical decision PERC rule and Pediatric PE Model were retrospectively applied to the patients.

RESULTS

In the study, PERC demonstrated a sensitivity of 60% and a specificity of 46% for the diagnosis of PE in children. When PE Model was evaluated for the children, it was found a 50% sensitivity and 75% specificity. Combining PE Model and PERC rule with D-dimer did not increase the specificity and sensitivity. Smoking was found to be relevant for PE in the childhood. Twenty-five percent of the patients had a genetic tendency for PE. All of the patients had an underlying disease as well.

CONCLUSION

None of the current risk assessment tools (PE Model, PERC, D-dimer) were found to be accurate in predicting PE. Further larger population studies are still required to develop a better diagnostic approach.

Modern Aspects of Anticoagulation System Disorders Diagnosis in Children with Different Polymorphisms in Coagulation Genes. Initial Results

Background. Hemostatic system pathology is topical and poorly studied issue in pediatrics. One of the main causes of coagulation pathway disorders associated with thrombotic events is abnormality in various parts of the hemostatic system. Vascular accidents are commonly caused by anticoagulation system factors deficiency. Conventionally, thrombosis is a common event in adult patients, and there is no adequate attention to disorders of primary physiological anticoagulants system in children. More often acquired anticoagulant proteins deficiency develops in presence of various pathological conditions, especially after the past infectious diseases. All these diseases (thrombophilia, trombotic events, cardiovascular pathology, nervous system diseases, genetic diseases) can occur separately and in association with each other, plus clinical picture of coagulation events may be similar. Objective. The aim of the study is to evaluate changes in the physiological anticoagulants system in children with different pathologies who have polymorphic variants in coagulation genes and who had new coronavirus infection. Methods. The study included 33 children who had severe coronavirus infection in family clusters and had severe chronic pathology potentially associated with disorders of the coagulation system (nervous system damage, hypertrophic cardiomyopathy, hereditary monogenic syndromes, hemato-mesenchymal dysplasia syndrome). All children underwent complete examination including clinical examination, laboratory, and instrumental diagnostics. Results. Preliminary study results indicate significant incidence of polymorphic variants in coagulation genes (one third of children with various diseases from the study). Some children had decreased activity of anticoagulation system glycoproteins (from 6% to 36%) that confirmed the topicality of the examination of anticoagulation system factors deficiency and the need for further dynamic follow-up, as well as revealing of trombophilia predictors in children in selected target groups. Study on revealing anticoagulation system disorders and mutations in coagulation genes will predict the risk of thrombotic disorders. Conclusion. The obtained results have confirmed the significant role of the ongoing study for comprehensive assessment of hemostatic system disorders in children. That will allow us to optimize the approach to diagnosis and personalize the management strategy for patients with different chronic pathologies and disorders of the natural anticoagulants system. The study is currently ongoing.

Secondary thrombosis prevention practice patterns in pediatrics: Results of an international survey

Background

Pediatric venous thromboembolism (VTE) rates continue to increase. Although most children present with transient provoking factors, some have persistent prothrombotic risks beyond the initial treatment period warranting secondary anticoagulation. Current pediatric VTE guidelines provide limited recommendations in this regard.

Objectives

Our primary objective was to identify key influences on pediatric thrombosis physicians' decisions to initiate secondary anticoagulation.

Methods

We targeted pediatric hematologists/oncologists internationally using Duration of Therapy for Thrombosis in Children, Children's Hospital Acquired Thrombosis consortium, and Venous Thromboembolism Network US pediatric subgroup membership rosters, who self-identified as primary outpatient thrombosis providers. Of 124 total surveys distributed, 61 complete surveys were evaluable. We defined secondary anticoagulation as anticoagulant use beyond the initial treatment period, on a daily basis (extended) or limited to periods of superimposed clinical risk factors (episodic).

Results

Pediatric thrombosis physicians surveyed indicated that they prescribe secondary anticoagulation in <25% of children despite persistent risks. Among those who indicated use of secondary anticoagulation, the preferred modality was extended anticoagulation in children with a history of recurrent unprovoked VTE (98%), chronic central venous catheter (74%), and potent thrombophilia (73%). Episodic anticoagulation was preferred in children with a history of mild thrombophilia (54%). Respondents were more likely to prescribe secondary anticoagulation for adolescents as opposed to children <12 years old.

Conclusions

Among pediatric thrombosis physicians surveyed, they perceived the prevalence of persistent prothrombotic risks to be high in children who have completed a course of anticoagulation for provoked VTE; however, estimated use of secondary anticoagulation was low. Studies involving real-world data are needed to further evaluate use of secondary anticoagulation in this setting.

A Case of a Pediatric Patient With Protein S Heerlen Polymorphism and Deep Venous Thrombosis

Hereditary protein S (PS) deficiency is a rare autosomal dominant disorder with increased risk of venous thromboembolism. The PS Heerlen polymorphism at codon 501 of the PROS1 gene is considered a variant of uncertain significance. It has since been shown that PS Heerlen has a reduced half-life, resulting in reduced levels of free PS. We report a case of an adolescent female with May Thurner syndrome and heterozygous PS Heerlen mutation resulting in a mild PS deficiency and venous thromboembolism. With this nonmodifiable risk factor, the patient received prolonged anticoagulation with strong consideration for lifelong prophylaxis.

Epidemiology, diagnosis and management of neonatal thrombosis: a single-center cohort study

The incidence of neonatal venous and arterial thrombosis ranges from 6.9 to 15/1000 neonatal ICU (NICU) admissions, and is likely an underestimate based on population demographics, frequency of surveillance and vascular catheterization. This retrospective study involving 234 infants reviewed the epidemiology, diagnosis, and management of neonatal thrombosis in a single, tertiary care institution over more than 10 years. The incidence of thrombosis was 25/1000 NICU admissions, with a preterm to term infant ratio of 1.5 : 1 and a slightly higher proportion of male sex (55.1%). The mean (range) gestational age and birth weight was 33.8 weeks (23-41.6) and 2360 g (512-5890). The median age (IQR) of thrombus diagnosis was 7 (3-17) days. Portal vein thrombosis was most prevalent (59.4%) compared with other sites of thrombosis. Almost three-quarter (171/234; 73.1%) of the thrombotic episodes were line-related, while infection and surgery were associated with 19.7% (46/234) and 10.7% (25/234), respectively. Twenty patients (8.3%) were screened for thrombophilia and 3 were positive; 2 for antithrombin deficiency, 1 for factor V Leiden gene mutation. Subjects were followed with imaging for 3 months with a treatment duration, mean (IQR) of 33.5 (10.8-42.5) days. Complete clot resolution was significantly higher in the anticoagulation group (48%; 17%; P = 0.03) compared with untreated patients. No group difference was noted for partial thrombus resolution (33.3%; 12.4%; P = 0.313). Anticoagulation halted thrombus progression (2.6 versus 12.4%; P = 0.025) and fewer treated patients failed to attend follow-up visits (6.5 versus 18.6%; P = 0.022). Well designed, multicenter prospective studies with larger sample sizes are required to confirm these findings.

Clinical and genetic features of Chinese pediatric patients with severe congenital protein C deficiency who first presented with purpura fulminans: A case series study and literature review

INTRODUCTION

Purpura fulminans (PF) is a hematological emergency that can be caused by severe congenital protein C (PC) deficiency. It has been rarely reported in the Chinese population. We aimed to characterize the clinical and genetic features of Chinese pediatric patients with severe congenital PC deficiency who first presented with PF.

MATERIALS AND METHODS

Twelve pediatric patients were diagnosed with severe congenital PC deficiency with PF, which was diagnosed based on our hospital records and previous reports from 1988 to July 2021 in China. We evaluated the clinical and genetic features of these patients.

RESULTS

Nine patients (9/12, 75%) had onsets that were observed within the first 48 h after birth. Six patients had a family history of thromboembolism. There was no consanguinity. Other symptoms were intracranial thrombosis or hemorrhage (4, 33.3%), ocular lesions (2, 16.7%), gastrointestinal hemorrhage (2, 16.7%) and kidney infarction before birth (1, 8.3%). All but one of the patients (one case not detected) had a plasma PC activity of <10%. The genetic study indicated that in the eight patients with inherited PC deficiency, two were homozygous, five were compound heterozygous and one was heterozygous for PC deficiency.

CONCLUSION

This is the first and largest case series of Chinese pediatric patients with severe congenital PC deficiency who first presented with PF. It has been shown that treatment with both fresh frozen plasma and anticoagulants is recommended when PC concentrate is not easily available, especially in developing countries.

Coexistence of antithrombin deficiency and suspected inferior vena cava atresia in an adolescent and his mother - case report and clinical implications

Background

Antithrombin deficiency (ATD) is an autosomal dominant thrombophilia presenting with varying phenotypes. In pediatric patients with ATD, thrombosis typically develops during the neonatal period or adolescence. However, to date there are no consistent recommendations on the therapeutic management of children with ATD. Inferior vena cava atresia (IVCA) belongs to a range of congenital or acquired vena cava malformations and is described as an independent risk factor for thrombosis.

The present case report explores two cases of combined ATD and IVCA in an adolescent and his mother.

Case presentation

A 14-year-old male presented with extensive deep venous thromboses (DVTs) of both lower extremities as well as an IVCA. The patient had previously been diagnosed with an asymptomatic ATD without therapeutic consequences at that time. His mother was suffering from an ATD and had herself just been diagnosed with IVCA, too.

The DVTs in the adolescent were treated by systemic anticoagulation and catheter-directed local thrombolysis causing favourable results. Yet, despite adequate oral anticoagulation the DVTs in both lower extremities reoccurred within 1 week after the patient was discharged from hospital. This time, thrombolysis could not be fully achieved. Surprisingly, probing and stenting of the IVCA was achieved, indicating an acquired IVCA which could have occurred after undetected thrombosis in early childhood.

Genetic analyses showed the same mutation causing ATD in both son and mother: heterozygote missense mutation c.248 T > C, p.(Leu83Pro), within the heparin binding domain of antithrombin. This mutation was never reported in mutation databases before.

Conclusions

To our knowledge this is the first case report discussing combined ATD and IVCA in two family members. Since ATDs present with clinical heterogeneity, taking a thorough family history is crucial for the anticipation of possible complications in affected children and decisions on targeted diagnostics and therapeutic interventions. Affected families must be educated on risk factors and clinical signs of thrombosis and need an immediate diagnostic workup in case of clinical symptoms. IVCA in patients with ATD could occur due to thrombotic occlusion at a very early age. Therefore, in case of family members with IVCA and ATD ultrasound screening in newborns should be considered.

Clinical Impact of Heritable Thrombophilia on Neonatal-Onset Thromboembolism: A Nationwide Study in Japan

OBJECTIVE

To clarify the incidence and genetic risk of neonatal-thromboembolism, we conducted a nationwide study exploring the impact of thrombophilia on neonatal-thromboembolism in Japan.

STUDY DESIGN

A questionnaire survey was conducted for perinatal centers in Japan, focusing on the clinical expression, genotype, treatment, and outcome of patients who developed thromboembolism within 28 days of birth from 2014 to 2018.

RESULTS

The estimated incidence of neonatal-thromboembolism was 0.39 cases per 10 000 live births. Intracranial lesions and purpura fulminans occurred in 66 and 5 of 77 patients, respectively. Fifty-eight (75.3%) infants presented within 3 days after birth. Four (5.2%) died, and 14 (18.2%) survived with disability. At the diagnosis, <20% plasma activity of protein C was noted in 16 infants, protein S (in 2), and antithrombin (in 1). Thirteen genetic tests identified 4 biallelic and 5 monoallelic protein C-variants but no protein S- or antithrombin-variants. Protein C-variants had purpura fulminans (P < .01), ocular bleeding (P < .01), positive-family history (P = .01), and death or disability (P = .03) more frequently than others. Protein C-variants were independently associated with disability (OR 5.74, 95% CI 1.16-28.4, P = .03) but not death. Four biallelic variants had serious thrombotic complications of neurologic disability, blindness, and/or amputation. Three monoallelic variants survived without complications. The only protein C-variant death was an extremely preterm heterozygote infant.

CONCLUSIONS

Monoallelic protein C-variants had a higher incidence of neonatal-thromboembolism than biallelic variants. Thrombophilia genetic testing should be performed in the setting of neonatal-thromboembolism and low protein C to identify the underlying genetic defect.

Semi-empirical anticoagulation model (SAM): INR monitoring during Warfarin therapy

The International Normalized Ratio (INR) monitoring is an essential component to manage thrombotic disease therapy. This study presents a semi-empirical model of INR as a function of time and assigned therapy (Warfarin, k-vitamin). With respect to other methodologies, this model is able to describe the INR using a limited number of parameters and is able to describe the time variation of INR described in the literature. The presented methodology showed great accuracy in model calibration [(trueness (precision)]: 0.2% (0.1%) to 1.2% (0.3%) for coagulation factors, from 5% (9%) to 9.7% (12%) for Warfarin-related parameters and 38% (40%) for K-vitamin-related parameters. The latter value was considered acceptable given the assumptions made in the model. It has two other important results: the first is that it was able to correctly estimate INR with respect to daily therapy doses taken from the literature. The second is that it introduces a single numeric semi-empirical parameter that is able to correlate INR/dose response to physiological and environmental condition of patients.

Neonatal thrombosis: risk factors and principles of prophylaxis

Data analysis on the pathogenesis and risk factors of neonatal thrombosis was carried out. The main risk factor of any neonatal thrombosis is central catheter installment, but other maternal, fetal and neonatal factors should be taken into consideration. We discuss the epidemiology of neonatal thrombosis and the main features of the hemostasis system in newborns, the most significant risk factors, including genetic and acquired thrombophilia. We consider the von Willebrand factor activity and ADAMTS-13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) level in the development of neonatal thrombotic microangiopathy. Finally, we discuss the basic principles of prevented neonatal thrombosis by using low molecular weight heparins.

A review on clotting disorders and retinal hemorrhages: Can they mimic abuse?

BACKGROUND

The characteristic findings of abusive head trauma (AHT) include retinal hemorrhages (RH). RH have many etiologies in childhood, which should be considered in the differential diagnosis of possible child abuse. The relationship between RH and thrombophilia in children is not well established.

OBJECTIVE

In this literature review, we sought to assess whether retinal findings in pediatric patients with thrombophilia could mimic those of AHT.

METHODS

A literature search was performed to identify all cases of thrombophilia in children less than 18 years old with ocular manifestations. Disorders of thrombophilia including protein C and S deficiency, factor V Leiden (FVL), prothrombin variant, MTHFR mutation, hyperhomocysteinemia, elevated factor VIII, and elevated lipoprotein (a) were considered. All cases of pediatric thrombophilia with retinal examination or intraocular bleeding were included. If provided, descriptions of the RH were reviewed.

RESULTS

Our initial search yielded 514 results. Forty-three articles met our inclusion criteria. We identified 3 children with RH within the AHT usual age range (<5 years old), ages 5 weeks and 7 weeks old, in the setting of thrombophilia. One child had ocular findings that could potentially mimic abuse. No other indicators of abuse were present in this case.

CONCLUSIONS

Based on previous reports, thrombophilia alone has not been shown to clearly mimic abusive head trauma. In reported cases of thrombophilia with RH, the clinical picture and ophthalmic findings are usually distinct from abuse.

Venous Thromboembolism among Noncritically Ill Hospitalized Children: Key Considerations for the Pediatric Hospital Medicine Specialist

Venous thromboembolism (VTE) is a leading cause of morbidity and preventable harm among noncritically ill hospitalized children. Several clinical factors relevant to the noncritically ill hospitalized child significantly increase the risk of VTE including the presence of central venous catheters, systemic inflammation, and prolonged immobilization. Although risk mitigation strategies have been described, the diagnosis, treatment, and prevention of VTE require standardization of institutional practices combined with multidisciplinary collaboration among pediatric hospitalists, hematologists, and other care providers. In this narrative review, we summarize the epidemiology of VTE, risk models identifying high-risk conditions associated with VTE, and prevention and treatment strategies. We further describe successful quality improvement efforts implementing institutional VTE risk stratification and thromboprophylaxis procedures. Finally, we highlight unique challenges facing pediatric hospital medicine specialists in the era of the COVID-19 pandemic, including caring for adults admitted to pediatric hospital units, and describe future research opportunities for VTE in the noncritically ill hospitalized child.

Diagnosis, Clinical Characteristics, and Treatment Modalities of Adolescent May-Thurner Syndrome-associated Deep Venous Thrombosis

May-Thurner syndrome (MTS) predisposes individuals to develop lower extremity deep venous thrombosis (DVT) because of compression of the left common iliac vein. Diagnosis of the anatomic obstruction is critical for effective therapy, as treatment by interventional radiology is often required in addition to anticoagulation to prevent thrombus progression and recurrence. The authors performed a retrospective review of adolescent patients who presented with MTS-associated DVT at a pediatric tertiary care center from 2009 to 2018 to assess for delays in MTS diagnosis after the presentation. Fourteen patients (median age 16.5 y, range, 13.8 to 17.9 y) were included, no DVTs were provoked by a central venous catheter. The median time from DVT to MTS diagnosis was 0.65 months (range, 0 to 21.5 mo). The initial imaging modalities used for DVT diagnosis were not able to diagnosis MTS. All patients were treated with anticoagulation and 13 underwent interventional therapy. Four patients had thrombus progression or recurrence, whereas 6 had complete thrombus resolution on follow-up imaging. Three patients who had a delayed MTS diagnosis had clinical worsening despite therapeutic anticoagulation requiring rehospitalization. Adolescent patients with "unprovoked" left lower extremity DVT should undergo appropriate imaging to diagnose MTS to allow for adequate medical and interventional therapy.

Central venous catheters are an important factor in paediatric thrombosis

AIM

To establish the incidence and characteristics of paediatric thrombosis (PT) in a Canadian tertiary care centre during the era of low molecular weight heparin (LMWH).

METHODS

A retrospective observational case study of all patients <18 years of age evaluated for arterial and venous thrombosis from May 2008 to July 2018 at McMaster Children's Hospital was conducted through the electronic medical record.

RESULTS

The incidence of PT was 52.2 per 10 000 hospital admissions (n = 477/91 462). Provoked thrombosis was more prevalent (88.9%, n = 424/477) than unprovoked (2.9%, n = 14/477) or idiopathic thrombosis (4%, n = 19/477). Half of PT were in children <2 years (51.2%, n = 244/477). Central vascular catheterisation was a contributory factor in more than half of thrombotic events (56.2%, n = 268/477), while trauma (1.1%, n = 5/477), oral contraceptives (4%, n = 19/477), infection (4%, n = 19/477), surgery (6.9%, n = 33/477) and malignancy (8.4%, n = 40/477) were also risk factors. Arterial ischaemic stroke was diagnosed in 11.1% of cases (n = 53/477), while pulmonary embolism was identified in 7.1% (n = 34/477) and 1.7% of cases were fatal (n = 8/477). LMWH was the first-line therapeutic of choice (47.8%, n = 228/477), with 28.1% (n = 134/477) requiring no intervention.

CONCLUSION

These data reiterate the elevated thrombosis risk to which infants and children with central vascular access are exposed.

Venous thrombosis in neonates

The incidence of thrombotic disorders in neonates and children is increasing with advances in diagnostic modalities, supportive care, and management of many health conditions. The developing coagulation system, need for intensive care, including catheterization, and co-morbid conditions are responsible for the relatively high risk of thrombosis in neonates compared to older children. This review addresses the advances over the last 3 years in neonatal thrombosis, with a focus on epidemiology, cerebral sinovenous thrombosis (CSVT), renal vein thrombosis (RVT), and portal vein thrombosis (PVT). The incidence of neonatal thrombosis in the contemporary era is reported to be 6.9-15 per 1,000 neonatal intensive care unit (NICU) admissions, compared to 2.4 per 1,000 NICU admissions reported in older registry data. The majority of recently published studies are small, retrospective, and from single centers, albeit they emphasize the need for definitive data to support the efficacy and safety of anticoagulation therapy (ACT) in the management of CSVT, RVT, and PVT. We highlight two important international initiatives geared towards improving the evidence base for these conditions. The International Pediatric Thrombosis Network (IPTN) is a collaboration of 74 centers across 27 countries (as of January 2021) which has started important projects like the international neonatal RVT registry, while the International Pediatric Stroke Study (IPSS) group is in the planning stages of a randomized controlled trial to evaluate the utility of ACT in the management of neonatal CSVT.

Thrombophilia screening revisited: an issue of personalized medicine

Clinical thrombophilia is the consequence of multiple gene and/or environment interactions. Thrombophilia screening requires a targeted patient with specific indication, in which a finding would have implications. Carrying out a thrombophilia examination in the physician's practice is often a cause of uncertainty and concern. The concerns begin in choosing the right patient to be examined, are associated with the time of investigation, with the choice of analysis, the test-material and with the correct interpretation of the results. Difficulties, which can influence the results, can occur with both organization and blood sampling. As common for any analysis, pre-analytical, analytical and post-analytical factors should be considered, as well as the possibility of false positive or false negative results. Finally, recommendation of correct therapeutic and prophylactic measures for the patient and his relatives is an additional focus. In this article we want to provide-on the basis of the evidence and personal experience-the theory of thrombophilia-investigation, the indications for testing, as well as practical recommendations for treatment options.

Incidence of VTE in asymptomatic children with deficiencies of antithrombin, protein C, and protein S: a prospective cohort study

Although antithrombin, protein C, and protein S defects are well-recognized inherited risk factors for venous thromboembolism (VTE) in adults, whether they predispose children to these vascular disorders as well is undefined. In a prospective cohort study, we assessed the incidence of spontaneous and risk period-related VTE in children who were family members of adults who, after an episode of symptomatic VTE, had then been identified as carriers of these abnormalities. A total of 134 children from 87 families were enrolled. Seventy (51.5%) of these children were carriers of an inherited defect, and the remaining 64 were not; the mean observation period was 4 years (range, 1-16 years) and 3.9 years (range, 1-13), respectively. Sixteen risk periods were experienced by carriers, and 9 by noncarriers. Six VTE occurred in the 70 carriers during 287 observation-years, accounting for an annual incidence of 2.09% patient-years (95% confidence interval, 0.8-4.5), compared with none in the 64 noncarriers during 248 observation-years. Of the 14 children with thrombophilia who experienced a risk period for thrombosis, 4 (28.6%) developed a VTE episode. The overall incidence of risk-related VTE was 25% per risk period (95% confidence interval, 6.8-64). In conclusion, the thrombotic risk in otherwise healthy children with severe inherited thrombophilia does not seem to differ from that reported for adults with the same defects. Screening for thrombophilia in children who belong to families with these defects seems justified to identify those who may benefit from thromboprophylaxis during risk periods for thrombosis.

Outcomes of symptomatic venous thromboembolism after haploidentical donor hematopoietic stem cell transplantation and comparison with human leukocyte antigen-identical sibling transplantation

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is regarded as a curative therapy for majority of hematologic malignancies and some non-malignant hematologic diseases. Venous thromboembolism (VTE) has become increasingly recognized as a severe complication following allogeneic hematopoietic stem cell transplantation (allo-HSCT).

OBJECTIVES

To show the characteristics of VTE after haploidentical donor hematopoietic stem cell transplantation (HID-HSCT) and make comparisons with matched related donor HSCT (MRD-HSCT).

PATIENTS/METHODS

A retrospective nested case-control study design was used, cases with VTE and matched controls were selected, with 3534 patients underwent HID-HSCT and 1289 underwent MRD-HSCT.

RESULTS

During follow-up, 114 patients with VTE were identified. The incidence of VTE in HID-HSCT group was similar to that of MRD-HSCT group (2.4% versus 2.3%, P = 0.92). In HID-HSCT group, VTE occurred at a median time of 92.5 days, which was earlier than MRD-HSCT group (243.5 days). For HID-HSCT, advanced disease status, cardiovascular risk factors, acute graft-versus-host disease (aGVHD), and relapse were the independent risk factors for VTE. For MRD-HSCT, cardiovascular risk factors, aGVHD, and relapse were associated with VTE. Overall survival (OS) of patients following HID-HSCT and MRD-HSCT were similar, but the OS in patients with VTE was significantly lower than patients without VTE.

CONCLUSIONS

There was no statistical difference in the incidence of VTE after HID-HSCT compared with MRD-HSCT. The development of VTE adversely impacted the OS after allo-HSCT.

Venous Thromboembolism in Children: From Diagnosis to Management

Venous thromboembolism (VTE) in children is a rare occurrence, although in recent decades we have seen an increase due to several factors, such as the rise in survival of subjects with chronic conditions, the use of catheters, and the increased sensitivity of diagnostic tools. Besides inherited thrombophilia, acquired conditions such as cardiovascular diseases, infections, chronic disorders, obesity and malignancy are also common risk factors for paediatric VTE. The treatment of paediatric VTE consists of the use of heparins and/or vitamin K antagonists to prevent dissemination, embolization, and secondary VTE. Randomized clinical trials of direct oral anticoagulants in paediatric VTE are ongoing, with the aim to improve the compliance and the care of patients. We reviewed the physiological and pathological mechanisms underlying paediatric thrombosis and updated the current diagnosis and treatment options.

A bibliometric analysis of publications on venous thromboembolism in children from 1988 to 2019

INTRODUCTION

Venous thromboembolism (VTE) in children not only imposes a heavy burden on the medical resources and economy of the society, but also seriously affects the growth and development of children, even threaten children's lives. A large number of publications have been performed in this field in recent years. In this bibliometric analysis, publications on VTE in children were examined and analyzed to explain the present research hotspots.

METHODS

Articles related to VTE in children published in the PubMed database from 1988 to June 18, 2019 were selected as the research sample. BICOMB software was used to retrieve the annual publications, journals, journal source countries and the high-frequency major medical subject headings (MeSH) terms on the articles. Then, the co-word matrix was constructed by BICOMB using the selected high-frequency MeSH terms. Next, gCLUTO software was used to analyze the matrix by double clustering and visual analysis in a strategy of hotspot identification. In addition, CiteSpace software was used to perform the knowledge map of co-authors to explore the core authors.

RESULTS

One thousand seven hundred seventy-nine articles on VTE in children were obtained. Seven hundred ninety academic journals distributed in 58 countries have published articles on VTE in children, and the developed countries and the United States were the major force in the journal source countries. Nowak-Göttl U occupied an important position in this field. We constructed a co-word matrix composing of 37 high-frequency MeSH terms, generated visual matrix and visual hill, and classified the hot-spots into 5 aspects based on 8 categories.

CONCLUSION

The results show that the research trend of children's VTE has been increasing gradually, and the sound achievement has been obtained in these hotspots in relation to the area of inherited thrombophilia, prevention and control, treatment, diagnosis, prevalence, risk factors, and complication study. However, there is a lack of communication and cooperation in this field, and the gap of national and regional research results is huge. To sum up, this study provides evidence and guidance for researchers, clinicians, and educators.

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.

Venous thromboembolism in childhood: where is Brazil after 20 years?

Due to the longer survival of critically ill children, venous thromboembolism is a problem which is becoming increasingly recognized in pediatric practice. In the last decades, several international studies have been published, shedding a light upon the epidemiology of this disease during childhood. These data show peculiarities in the clinical presentation and the significant morbidity and mortality. The new "epidemic of thrombosis" in pediatric hospitals points toward the urgent need for specific treatment and prevention protocols targeting this population. In Brazil, knowledge regarding this disease remains scarce. The lack of epidemiological data impacts both the clinical care and the design of specific public policies in the field. Thus, a national registry of pediatric venous thromboembolism is relevant to the proposal of an appropriate plan of action to create a qualified net of assistance. The improvement in educational initiatives related to the field of Pediatric Hemostasis is also very important. In this review, we have updated the epidemiological, clinical and therapeutic aspects of the disease, as well as the prevention strategies.

Genotype phenotype correlation in a pediatric population with antithrombin deficiency

Inherited antithrombin (AT) deficiency is a rare autosomal dominant disorder, caused by mutations in the AT gene (SERPINC1). Considering that the genotype phenotype relationship in AT deficiency patients remains unclear, especially in pediatric patients, the aim of our study was to evaluate genotype phenotype correlation in a Serbian pediatric population. A retrospective cohort study included 19 children younger than 18 years, from 15 Serbian families, with newly diagnosed AT deficiency. In 21% of the recruited families, mutations affecting exon 4, 5, and 6 of the SERPINC1 gene that causes type I AT deficiency were detected. In the remaining families, the mutation in exon 2 causing type II HBS (AT Budapest 3) was found. Thrombosis events were observed in 1 (33%) of those with type I, 11 (85%) of those with AT Budapest 3 in the homozygous respectively, and 1(33%) in the heterozygous form. Recurrent thrombosis was observed only in AT Budapest 3 in the homozygous form, in 27% during initial treatment of the first thrombotic event. Abdominal venous thrombosis and arterial ischemic stroke, observed in almost half of the children from the group with AT Budapest 3 in the homozygous form, were unprovoked in all cases.Conclusion: Type II HBS (AT Budapest 3) in the homozygous form is a strong risk factor for arterial and venous thrombosis in pediatric patients. What is Known: • Inherited AT deficiency is a rare autosomal dominant disorder, caused by mutations in the SERPINC1gene. • The genotype phenotype correlation in AT deficiency patients remains unclear, especially in pediatric patients. What is New: • The genetic results for our paediatric population predominantly showed the presence of a single specific mutation in exon 2, that causes type II HBS deficiency (AT Budapest 3). • In this group thrombosis mostly occurred as unprovoked, in almost half of them as abdominal thrombosis or stroke with high incidence of recurrent thrombosis, in 27% during initial treatment.

Salvage pulmonary thromboembolectomy for massive pulmonary embolism in a child presented with syncope and subsequent cardiac arrest

Pulmonary embolism is frequently under-recognised in children and, therefore, a high index of suspicion should be exerted on patients with exertional dyspnoea, presyncope/syncope and unexplained cardiopulmonary arrest. We discuss a 10-year-old previously healthy girl who presented with syncope and subsequent cardiac arrest related to massive pulmonary embolism and was salvaged successfully by emergent pulmonary embolectomy.

The Impact of Multiple Risk Factors for Venous Thromboembolism and Its Implications for Management

Venous thromboembolism (VTE) is a rare multifactorial disorder in childhood with an annual incidence of about 0.07 to 0.14 per 10 000 children. A 15-year-old female with a body mass index of 48 kg/m² who endorsed oral contraceptive use presented with clinical findings consistent with deep venous thrombosis along with the presence of a pulmonary embolism. Further workup revealed that the patient was heterozygous for factor V Leiden and homozygous for prothrombin G20210A mutations. There are no current pediatric guidelines for the antithrombotic management of patients with multiple risk factors for VTE. Two such risk factors, obesity and the use of estrogen-containing hormone contraceptives, have been implicated in adult VTE cases but have not been clearly delineated in pediatric patients. The need for guidance regarding the VTE management of these patients has become more apparent given the increasing incidence of childhood obesity and the number of adolescents using oral contraceptives. Additionally, thrombophilia testing remains controversial though testing may be indicated in asymptomatic first-degree relatives and in families with antithrombin, protein C, or protein S deficiencies. Given the increased incidence of multiple risk factors for VTE, there is also a need to develop a comprehensive risk assessment tool for pediatric patients at high risk of VTE.

Management of antithrombin deficiency: an update for clinicians

Introduction. Antithrombin is a serpin that inhibits multiple procoagulant serine proteases and acts as an endogenous anticoagulant. Thus, congenital antithrombin deficiency constitutes a major thrombophilic state, the most severe so far. Areas covered. In the present work, we globally review the biology, genetics, diagnosis, and management of congenital antithrombin deficiency, and also discuss puzzling questions and future perspectives regarding this severe inherited thrombophilia. Expert opinion. Although this disorder exerts high clinical heterogeneity, many carriers will need careful and long-term anticoagulation and/or thromboprophylaxis, especially in high-risk situations, such as surgery and pregnancy. Notably, antithrombin concentrates constitute a considerable arsenal for both treatment and prevention of acute venous thrombosis in subjects with antithrombin deficiency. Current evidences are based almost exclusively on retrospective case series, so an integrated functional, biochemical and molecular characterization will be of clinical relevance and guide hematologists' personalized decisions.

Deep Vein Thrombosis in a Young, Healthy Baseball Catcher: A Case Report and Review of the Literature

Venous thromboembolism is becoming increasingly recognized as a significant cause of morbidity and mortality in the hospitalized pediatric population. However, young healthy athletes can present with unique risk factors for deep vein thrombosis (DVT) that can be overlooked. Here we report a case of an adolescent male with no inherited risk factors or prior history of DVTs who developed a right femoral vein DVT in the context of playing catcher in baseball after recovering from a bout of streptococcal pharyngitis. We review the evidence that suggests that repetitive squatting-induced compression of the femoral vein can cause the venous stasis and endothelial microtrauma that contributed to the formation of this thrombus.

Incidence and features of thrombosis in children with inherited antithrombin deficiency

Pediatric thromboembolism (≤18 years) is very rare (0.07-0.14/10,000/year) but may be more prevalent in children with severe thrombophilia (protein C, protein S or antithrombin deficiency). The aim of this study was to define the prevalence and clinical characteristics of pediatric thrombosis in subjects with inherited antithrombin deficiency. Our observational retrospective multicentric study from two countries recruited 968 patients of any age from 441 unrelated families with genetically, biochemically and functionally characterized antithrombin deficiency. Seventy-three subjects (7.5%) developed thrombosis before 19 years of age. Two high-risk periods for thrombosis were identified: adolescence (12-18 years, n=49) with thrombus localization (lower limb deep venous thrombosis or pulmonary embolism) and triggering factors common to adults (oral contraceptives, surgery or pregnancy); and the neonatal period (<30 days, n=15) with idiopathic thrombosis at unusual sites. The clinical evaluation of pediatric thrombosis in subjects with antithrombin deficiency revealed: i) a high prevalence of cerebral sinovenous thrombosis (n=13, 17.8%), mainly at young age (8 neonates and 4 children <6 years); ii) severe outcome with fatality in six cases (3 neonates, two of them homozygous for p.Leu131Phe). The majority of subjects (76.7%) carried quantitative type I deficiency. This retrospective analysis includes the largest cohort of subjects with inherited antithrombin deficiency so far and provides strong evidence for an increased risk of pediatric thrombosis associated with this thrombophilia (300-fold compared with the general population: 0.41%/year vs. 0.0014%/year, respectively). Our results support testing for antithrombin deficiency in children of affected families, particularly in case of type I deficiency.

Is lipoprotein(a) a risk factor for ischemic stroke and venous thromboembolism?

The structural similarity with plasminogen as well as thrombogenic and atherogenic in vitro functions raise the question if lipoprotein(a) (Lp(a)) is a risk factor for venous thromboembolism (VTE) and ischemic stroke. Numerous case-control and prospective studies using different cut-off values to define high Lp(a) generated conflicting evidence for both VTE and ischemic stroke. Several meta-analyses demonstrated independent associations of elevated Lp(a) with a history of VTE or ischemic stroke. However, the evidence of prospective studies for associations of Lp(a) with incident stroke or recurrent VTE remains inconclusive. For ischemic stroke, data suggest that Lp(a) increases the risk of large-artery atherosclerosis stroke, but not cardioembolic or lacunar stroke. Lp(a) may increase the risk of VTE in the presence of additional thrombophilic risk factors. Larger cohort studies are needed to elaborate the importance of higher Lp(a) cut-offs and interactions with other risk factors and subgroups of stroke or VTE. The value of Lp(a) to estimate residual vascular risk after the first thromboembolic event remains to be adequately explored.

Thrombosis in Children: Approach to Anatomic Risks, Thrombophilia, Prevention, and Treatment

Pediatric venous thromboembolism (VTE) is increasing in incidence but minimal data exist for best practices regarding therapy, use of thrombophilia testing, and management of long-term complications. Classification schema use anatomic location and presence of clinical or thrombophilic inciting factors. There are a small number of risk-assessment and risk-modeling systems for incident VTE, but all suffer from low numbers, single-institution design, and lack of prospective validation. Acute treatment is limited to heparin products and thrombolysis may be indicated in specific situations. In addition, chronic postthrombotic comorbidities are expected to increase in incidence and lack evidence-based treatment paradigms.

Hypercoagulable states in arterial and venous thrombosis: When, how, and who to test?

Evaluation for underlying hypercoagulable states in patients with thrombosis is a frequent clinical conundrum. Testing for thrombophilias is often reflexively performed without strategic approach nor clear appreciation of the clinical implications of such results. Guidelines vary in the appropriate utilization of thrombophilia testing. In this review, we discuss the more commonly encountered inherited and acquired thrombophilias, their association with initial and recurrent venous thromboembolism, arterial thromboembolism, and role in women's health. We suggest an approach to thrombophilia testing guided by the clinical presentation, suspected pathophysiology, and an understanding of how such results may affect patient care.