Genetic prothrombotic mutations are common in neonates but are not associated with umbilical catheter-associated thrombosis

Association between Portal Vein Thrombosis after Umbilical Vein Catheterization and Neonatal Asphyxia

INTRODUCTION

Neonatal portal vein thrombosis (PVT) is frequently related to umbilical venous catheterization (UVC), but risk factors remain unclear. This study aims to analyze the variables associated to PVT in near- to full-term newborns with UVC, with a focus on newborns exposed to controlled therapeutic hypothermia (CTH) for hypoxic ischemic encephalopathy (HIE).

METHODS

This is retrospective cohort study of infants delivered at or after 36 weeks and with a birthweight over 1,500 g. All infants were assessed for UVC location and PVT using ultrasonography performed between day 5 and day 10 after catheterization.

RESULTS

Among 213 eligible patients, PVT was diagnosed in 57 (27%); among them, 54 (95%) were localized in the left portal vein branch. With all significant factors in univariate analysis considered, higher gestational age at birth (adjusted OR 1.35; 95% CI: 1.12-1.64, p = 0.002) and duration of UVC placement (adjusted OR 1.36; 95% CI: 1.11-1.67, p = 0.004) were the main risk factors of PVT. Among 87 infants who were cooled for HIE, 31 (36%) had PVT compared to 26 (21%) in infants without CTH. Using a multivariate model including variables linked to treatment procedures only, an increased PVT incidence was statistically associated with UVC duration (adjusted OR 1.33; 95% CI: 1.08; 1.63, p = 0.01) and CTH (adjusted OR 1.94; 95% CI: 1.04-3.65, p = 0.04).

CONCLUSION

Left PVT was frequently observed in near- to full-term neonates with UVC. Among factors linked to treatment procedures, both duration of UVC and CTH exposure for HIE were found to be independent risk factors of PVT.

Incidence of umbilical vein catheter-associated thrombosis of the portal system: A systematic review and meta-analysis

BACKGROUND

The use of umbilical venous catheters (UVCs) in the perinatal period may be associated with severe complications, including the occurrence of portal vein thrombosis (PVT).

AIM

To assess the incidence of UVC-related PVT in infants with postnatal age up to three months.

METHODS

A systematic and comprehensive database searching (PubMed, Cochrane Library, Scopus, Web of Science) was performed for studies from 1980 to 2020 (the search was last updated on November 28, 2020). We included in the final analyses all peer-reviewed prospective cohort studies, retrospective cohort studies and case-control studies. The reference lists of included articles were hand-searched to identify additional studies of interest. Studies were considered eligible when they included infants with postnatal age up to three months with UVC-associated PVT. Incidence estimates were pooled by using random effects meta-analyses. The quality of included studies was assessed using the Newcastle-Ottawa scale. The systematic review was performed according to the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) guidelines.

RESULTS

Overall, 16 studies were considered eligible and included in the final analyses. The data confirmed the relevant risk of UVC-related thrombosis. The mean pooled incidence of such condition was 12%, although it varied across studies (0%-49%). In 15/16 studies (94%), diagnosis of thrombosis was made accidentally during routine screening controls, whilst in 1/16 study (6%) targeted imaging assessments were carried out in neonates with clinical concerns for a thrombus. Tip position was investigated by abdominal ultrasound (US) alone in 1/16 (6%) studies, by a combination of radiography and abdominal US in 14/16 (88%) studies and by a combination of radiography, abdominal US and echocardiography in 1/16 (6%) studies.

CONCLUSION

To the best of our knowledge, this is the first systematic review specifically investigating the incidence of UVC-related PVT. The use of UVCs requires a high index of suspicion, because its use is significantly associated with PVT. Well-designed prospective studies are required to assess the optimal approach to prevent UVC-related thrombosis of the portal system.

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.

Outcomes following neonatal portal vein thrombosis: A descriptive, single-center study and review of anticoagulant therapy

BACKGROUND

Neonatal portal vein thrombosis (PVT) is uncommon with potentially serious complications that may manifest in infancy and childhood.

OBJECTIVE

The primary aim of our study was to describe the short-term and long-term outcomes of neonatal PVT.

METHODS

A retrospective chart review was conducted from 2008 to 2016 of neonates diagnosed with PVT. A systematic review was also performed from 2000 to 2018 to evaluate anticoagulant therapy (ACT) in neonatal PVT.

RESULTS

Forty-four premature and 30 term infants (mean gestational age 30.7 vs 39.1 weeks, respectively) had PVT. Sixty-eight involved the left portal vein, one involved only the main portal vein, and 5 involved ≥1 vein. PVT was catheter associated in 46 (62%); none of the 7 neonates tested had thrombophilia. Of 74 neonates, 19 (26%) received ACT and 55 (74%) were untreated. The mean follow-up duration was 16.6 months (SD = 17.62; range, 0-89.6); 59.5% were followed for ≥6 months. On last ultrasound examination, thrombus resolution was documented in treated (ACT; n = 19) and nontreated (n = 55) neonates: 12 (63%) versus 32 (58%) with complete resolution, 1 (5%) versus 6 (11%) partial, 0 versus 1 (2%) extension, and 6 (32%) versus 16 (29%) had nonprogressive lesions, respectively. Seventy-one (96%) had no complications. Seventy-one articles met inclusion criteria for the systematic review and 19 were retained for analysis after assessment.

CONCLUSIONS

PVT resolution rate was similar to previous reports. Although a low complication rate was detected, longer follow-up is necessary to determine the need for early treatment and the precise incidence of outcomes such as portal hypertension.

Experience and Prognosis of Systemic Neonatal Thrombosis at a Level III NICU

OBJECTIVE

The objective of this article was to evaluate neonates diagnosed systemic thrombosis and their outcomes.

METHODS

We retrospectively evaluated data of neonatal systemic thrombosis between January 2011 and December 2016.

RESULTS

Among 4376 hospitalized, 30 neonates (0.69%) were diagnosed systemic thrombosis. Their mean birth weight was 2422±1152 g (680 to 4750 g), gestational age was 35±5.4 weeks (25 to 41 wk). There were 25 neonates (83.3%) with venous, 5 patients (16.7%) with arterial thrombosis. The most common sites that thrombi localized were major vessels (n=11) and central nervous system (n=8). Central catheter insertion (76.7%) and prematurity (46.7%) were the most common risk factors. Congenital prothrombotic risk factors included G1691A mutation in factor V Leiden (n=1), mutation in factor XIII (n=1), C677T mutation in methylenetetrahydrofolate reductase (n=6). More than 1 congenital risk factor was identified in 5 patients. The patients were treated with low-molecular weight heparin. The mortality rate was 13.3% (n=4). Two patients required amputation (left foot, left upper extremity). Unilateral renal atrophy (n=1), cerebral palsy (n=2), hemiparesis (n=1) were identified among followed 24 patients.

CONCLUSIONS

Critically ill neonates are at risk for thrombosis, and devastating consequences can result. As indwelling catheters and prematurity are important, careful monitorization, early diagnosis and therapy, cautious care of central catheter might reduce the incidence and adverse outcome.

Femoral Vein Catheter is an Important Risk Factor for Catheter-related Thrombosis in (Near-)term Neonates

Central venous catheters (CVCs) in neonates are associated with an increased risk of thrombosis. Most reports focus on umbilical venous catheters (UVCs) and peripherally inserted central catheters (PICCs), whereas data available on femoral venous catheters (FVCs) are limited. We performed a retrospective cohort study in all neonates (gestational age ≥34 wk) with CVCs. The primary outcome was the occurrence of thrombosis in CVCs. The secondary outcomes were possible risk factors for thrombosis, the thrombotic incidence in FVCs, UVCs, and PICCs, and clinical aspects of thrombosis in these groups. A total of 552 neonates received a total of 656 catheters, including 407 (62%) UVCs, 185 (28%) PICCs, and 64 (10%) FVCs. Thrombosis was detected in 14 cases, yielding an overall incidence of 2.1% or 3.6 events per 1000 catheter days. FVC was significantly associated with the occurrence of thrombosis when compared with UVC (P=0.02; odds ratio, 3.8; 95% confidence interval, 1.2-12.0) and PICC (P=0.01; odds ratio, 8.2; 95% confidence interval, 1.6-41.7). The incidence of thrombosis was higher in FVCs than in UVCs and PICCS, that is, 7.8% (5/64), 1.7% (7/407), and 1.1% (2/185), respectively (P<0.01). The number of thrombotic events per 1000 catheter days was 12.3 in FVCs, 3.2 in UVCs, and 1.5 in PICCs (P<0.05). We concluded that thrombosis occurs more frequently in FVCs than in other CVCs.

Inherited Thrombophilia in Pediatric Venous Thromboembolic Disease: Why and Who to Test

Venous thromboembolic disease in childhood is a multifactorial disease. Risk factors include acquired clinical risk factors such as a central venous catheter and underlying disease and inherited thrombophilia. Inherited thrombophilia is defined as a genetically determined tendency to develop venous thromboembolism. In contrast to adults, acquired clinical risk factors play a larger role than inherited thrombophilia in the development of thrombotic disease in children. The contributing role of inherited thrombophilia is not clear in many pediatric thrombotic events, especially catheter-related thrombosis. Furthermore, identification of inherited thrombophilia will not often influence acute management of the thrombotic event as well as the duration of anticoagulation. In some patients, however, detection of inherited thrombophilia may lead to identification of other family members who can be counseled for their thrombotic risk. This article discusses the potential arguments for testing of inherited thrombophilia, including factor V Leiden mutation, prothrombin mutation, and deficiencies of antithrombin, protein C, or protein S and suggests some patient groups in childhood, which may be tested.

Neonatal Venous Thromboembolism

Neonates are the pediatric population at highest risk for development of venous thromboembolism (VTE), and the incidence of VTE in the neonatal population is increasing. This is especially true in the critically ill population. Several large studies indicate that the incidence of neonatal VTE is up almost threefold in the last two decades. Central lines, fluid fluctuations, sepsis, liver dysfunction, and inflammation contribute to the risk profile for VTE development in ill neonates. In addition, the neonatal hemostatic system is different from that of older children and adults. Platelet function, pro- and anticoagulant proteins concentrations, and fibrinolytic pathway protein concentrations are developmentally regulated and generate a hemostatic homeostasis that is unique to the neonatal time period. The clinical picture of a critically ill neonate combined with the physiologically distinct neonatal hemostatic system easily fulfills the criteria for Virchow's triad with venous stasis, hypercoagulability, and endothelial injury and puts the neonatal patient at risk for VTE development. The presentation of a VTE in a neonate is similar to that of older children or adults and is dependent upon location of the VTE. Ultrasound is the most common diagnostic tool employed in identifying neonatal VTE, but relatively small vessels of the neonate as well as frequent low pulse pressure can make ultrasound less reliable. The diagnosis of a thrombophilic disorder in the neonatal population is unlikely to change management or outcome, and the role of thrombophilia testing in this population requires further study. Treatment of neonatal VTE is aimed at reducing VTE-associated morbidity and mortality. Recommendations for treating, though, cannot be extrapolated from guidelines for older children or adults. Neonates are at risk for bleeding complications, particularly younger neonates with more fragile intracranial vessels. Developmental alterations in the coagulation proteins as well as unique pharmacokinetics must also be taken into consideration when recommending VTE treatment. In this review, epidemiology of neonatal VTE, pathophysiology of neonatal VTE with particular attention to the developmental hemostatic system, diagnostic evaluations of neonatal VTE, and treatment guidelines for neonatal VTE will be reviewed.

Association of thrombophilia and catheter-associated thrombosis in children: a systematic review and meta-analysis

Essentials It is unclear if thrombophilia increases the risk of catheter-associated thrombosis in children. We conducted a meta-analysis on thrombophilia and pediatric catheter-associated thrombosis. Presence of ≥1 trait confers additional risk of venous thrombosis in children with catheters. Limitations of included studies preclude us from recommending routine thrombophilia testing.

SUMMARY

Background The association between thrombophilia and deep vein thrombosis (DVT) associated with central venous catheter (CVC) use, the most important pediatric risk factor for thrombosis, is unclear in children. Pediatric studies with small sample sizes have reported conflicting results. We sought to evaluate whether, among children with CVCs, thrombophilia increases the risk of CVC-associated DVT (CADVT). Materials and methods We systematically searched MEDLINE, EMBASE, the Web of Science, the Cochrane Central Register for Controlled Trials, PubMed and reference lists for controlled studies published from the inception of the database until September 2015. Included were studies of children aged <21 years with CVCs who were systematically tested for thrombophilic traits that are commonly screened for in clinical practice. Pooled prevalence rates and pooled odds ratios (pORs) of CADVT with thrombophilia were estimated by use of a random effects model. Results We analyzed 16 cohort studies with 1279 children, 277 of whom had CADVT, and with 12 traits tested. There was significant heterogeneity in the included studies. The presence of one or more traits was associated with CADVT (pOR 3.20; 95% confidence interval [CI] 1.56-6.54). Although the prevalence of most traits was < 0.10, children with protein C deficiency, elevated factor VIII levels and the FV Leiden mutation had an increased prevalence of CADVT. The association with thrombophilia seemed to be stronger for symptomatic CADVT (pOR 6.71; 95% CI 1.93-23.37) than for asymptomatic CADVT (pOR 2.14; 95% CI 1.10-4.18). Conclusions On the basis of the low prevalence of specific traits, the relatively weak association with CADVT, and the limitations of the included studies, we cannot recommend routine testing of thrombophilias in children with CADVT.

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.

No impact of endogenous prothrombotic conditions on the risk of central venous line-related thrombotic events in children: results of the KIDCAT study (KIDs with Catheter Associated Thrombosis)

BACKGROUND AND OBJECTIVE

Central venous lines (CVLs) are the major exogenous risk factor for deep venous thrombosis (DVT) in children. The study objective was to assess whether endogenous prothrombotic conditions contribute to the risk of CVL-related DVT in children.

METHODS

This was a cohort study of consecutive children with heart disease requiring CVLs for perioperative care. CVLs were inserted percutaneously in the upper venous system and patients received prophylaxis with continuous unfractionated heparin (50 u kg(-1)  d(-1) ). Blood samples to test for prothrombotic conditions were collected prospectively and assayed in a blinded fashion. Outcome assessment was by screening for DVT by venography, venous ultrasound and echocardiography.

RESULTS

The study population consisted of 90 children, median age 2.7 years (0 months-18 years). Prevalence rates of antithrombin deficiency, protein C deficiency, protein S deficiency, heterozygous factor V Leiden, prothrombin G20210A mutation, methylentetrahydrofolate C677TT genotype, hyperhomocysteinemia, lupus anticoagulant, anticardiolipin antibodies and increased levels of lipoprotein (a) were within the range reported for the general population. At least one prothrombotic condition was present in 38% of children and combined abnormalities in 8%. The incidence of DVT was 28% (25/90), and most DVTs were asymptomatic. None of the prothrombotic conditions showed a significant association with DVT. The population attributable risk (i.e. the risk of DVT in the overall population attributable to a specific condition) did not exceed 2.2%.

CONCLUSION

Prothrombotic conditions did not have an important impact on the risk of DVT in children with short-term CVLs. The results of the study suggest that screening for prothrombotic conditions is not justified in this setting.

Central venous catheter-related thrombosis and thromboprophylaxis in children: a systematic review and meta-analysis

OBJECTIVES

In preparation for a pediatric randomized controlled trial on thromboprophylaxis, we determined the frequency of catheter-related thrombosis in children. We also systematically reviewed the pediatric trials on thromboprophylaxis to evaluate its efficacy and to identify possible pitfalls in the conduct of these trials.

PATIENTS/METHODS

We searched MEDLINE, EMBASE, Web of Science and the Cochrane Central Register for Controlled Trials for articles published until December 2013. We included cohort studies and trials on patients aged 0-18 years with central venous catheters who underwent active surveillance for thrombosis with radiologic imaging. We estimated the pooled frequency of thrombosis and the pooled risk ratio (RR) with thromboprophylaxis by using a random effects model.

RESULTS

From 2651 articles identified, we analyzed 37 articles with 3128 patients. The pooled frequency of thrombosis was 0.20 (95% confidence interval [CI] 0.16-0.24). In 10 trials, we did not find evidence that heparin-bonded catheters (RR 0.34; 95%CI 0.01-7.68), unfractionated heparin (RR 0.93; 95% CI 0.57-1.51), low molecular weight heparin (RR 1.13; 95% CI 0.51-2.50), warfarin (RR 0.85; 95%CI 0.34-2.17), antithrombin concentrate (RR 0.76; 95% CI 0.38-1.55) or nitroglycerin (RR 1.53; 95%CI 0.57-4.10) reduced the risk of thrombosis. Most of the trials were either not powered for thrombosis or were powered to detect large, probably unachievable, reductions in thrombosis. Missing data on thrombosis also limited these trials.

CONCLUSIONS

Catheter-related thrombosis is common in children. An adequately powered multicenter trial that can detect a modest, clinically significant reduction in thrombosis is critically needed. Missing outcome data should be minimized in this trial.

Clinical outcome of umbilical artery catheter-related thrombosis - a cohort study

OBJECTIVE

To reveal the incidence of umbilical artery catheter-related thrombosis (UACRT), the associated risk factors and the natural history of clot formation and regression.

STUDY DESIGN

A prospective cohort study. An umbilical artery catheter was inserted in 61 infants, who were evaluated and followed by serial duplex ultrasound studies for the development of UACRT, renal artery resistance index (RI) and clot resolution. Maternal and infant clinical variables were correlated with the characteristics of thrombi.

RESULT

Nineteen infants developed UACRT, all resolved spontaneously without sequella; most had maximal length at the first evaluation. No correlation was found between the thrombus length and time to resolution. The RI did not differ between the infants with and without UACRT. After adjusting for possible confounding, catheter days was the only covariate associated with UACRT.

CONCLUSION

Asymptomatic UACRT in our cohort was a self-resolving disease; it was associated with catheter days and did not necessitate medical treatment.

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.

Diagnosis and management of central-line-associated thrombosis in newborns and infants

Although the use of central lines has many valuable applications in neonates and infants, they may cause serious mechanical, infectious and thrombotic complications. In fact, the use of central lines is the main cause for thrombosis in this age group. The frequency of central-line-related thrombosis in neonates and infants is reported to be as low as 1% when including only symptomatic cases, around 44% when systematically screened for thrombosis, and as high as 65% in autopsy studies. The risk factors for line-related thrombosis in neonates and infants include those associated with the underlying medical conditions, the duration of the line in situ, the placement of the umbilical artery catheter and the therapy used through the line. The contribution of inherited and acquired thrombophilia to central-line-related thrombosis is controversial, and the data are not sufficiently consistent to make a firm recommendation for thrombophilia screening for neonates and infants with central-line-related thrombosis. Most experts will recommend pursuing a thrombophilia work-up in the setting of a significant thrombosis event and will recommend avoiding thrombophilia work-up in subclinical and asymptomatic central-line-related thrombosis. The management of line-related thrombosis is based on expert opinion guidelines and is largely dependent on the type of the catheter and the further requirement of the catheter. Continuous heparin infusion through the central lines prevents catheter occlusion, but has no effect on occurrence of thrombosis. Currently no definitive recommendations exist for thromboprophylaxis in children, infants and neonates with central lines.

Neonatal portal vein thrombosis: diagnosis and management

Neonatal portal vein thrombosis (PVT) is an increasingly recognized event. Patients are generally asymptomatic in the neonatal period. The diagnosis is made with Doppler ultrasound. Umbilical catheterization, exchange transfusion and sepsis are risk factors for neonatal PVT. Thrombophilia is possibly a contributing risk factor. Although there are potential serious acute complications such as hepatic necrosis, the outcome is good in the majority of cases, followed up to 8 years of age. Thrombus resolution occurs in 30-70% in days to months. Liver lobe atrophy may occur following PVT, and does not appear to be associated with any impairment of liver function. Non-occlusive thrombosis is more likely to resolve than non-occlusive thrombosis. A subset of patients without resolution is at risk for developing portal hypertension over the next decade of life. There are no current defining features present during the neonatal period to enable identification of neonates at risk for portal hypertension. There is no evidence that anticoagulation therapy improves time to resolution or decreases the likelihood of portal hypertension. Anticoagulation therapy may be considered. A management algorithm is proposed.

Antiphospholipid syndrome in a neonate

Antiphospholipid syndrome presenting in the neonatal period is very rare. Although antiphospholipid antibodies from mothers with antiphospholipid syndrome can cross the placenta and put their neonates at risk, the occurrence of thrombotic complications in these neonates is uncommon. We present a 10-day-old neonate who developed Klebsiella sepsis with arterial gangrene of the left lower limb. Investigations revealed thrombosis of the left femoral artery with both the mother and the neonate positive for antiphospholipid antibodies. In conclusion, passive transfer of antiphospholipid antibodies from mothers to their offspring can be associated with significant complication in the presence of secondary risk factors.

Umbilical vascular catheter associated portal vein thrombosis detected by ultrasound

OBJECTIVE

To determine catheter-associated thrombosis by color Doppler ultrasound and to detect duration of catheter placement as a risk factor for thrombosis.

METHODS

All newborn infants with umbilical vascular catheterization for more than 6 h duration were included in this study. Color Doppler ultrasound examination was performed within 24-48 h of catheter insertion, 48-72 h after its withdrawal and weekly until hospital discharge or clot resolution.

RESULTS

Portal vein thrombosis (PVT) was determined in five cases (3.04%) of 164 infants received umbilical vascular catheterization. The mean duration of catheter placement in patients with PVT was 3.4 ± 1.94 days, which was not significantly different from infants without thrombosis (3.5 ± 2.03). Thrombosis was completely recanalized and resolved after 3-6 weeks in three survived neonates. There was history of exchange transfusion for hyperbilirubinemia via umbilical vein in two neonates with PVT.

CONCLUSIONS

Catheter-associated portal venous thrombosis was uncommon in our study. The duration of catheter placement was not longer in patients with portal vein thrombosis than those without thrombosis.

Asparaginase-related venous thrombosis in UKALL 2003- re-exposure to asparaginase is feasible and safe

We report the incidence and outcome of venous thrombosis (VT) in the UK acute lymphoblastic leukaemia (ALL) 2003 trial. VT occurred in 59/1824 (3.2%) patients recruited over 5 years with 90% occurring during a period of Asparagine depletion. Pegylated Escherichia Coli Asparaginase (Peg-ASP) 1000 units/m(2) was used throughout. Thirty-four children received further Peg-ASP, most with concurrent heparin prophylaxis. There were no episodes of bleeding or recurrent thrombosis. Optimal Asparagine depletion is central to success of modern regimes for treatment of ALL. This report confirms a significant risk of thrombosis with such therapy, but demonstrates that re-exposure to Asparaginase is feasible and safe.

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

BACKGROUND

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

Thrombosis in the critically ill neonate: incidence, diagnosis, and management

Among children, newborn infants are most vulnerable to development of thrombosis and serious thromboembolic complications. Amongst newborns, those neonates who are critically ill, both term and preterm, are at greatest risk for developing symptomatic thromboembolic disease. The most important risk factors are inflammation, DIC, impaired liver function, fluctuations in cardiac output, and congenital heart disease, as well as exogenous risk factors such as central venous or arterial catheters. In most clinically symptomatic infants, diagnosis is made by ultrasound, venography, or CT or MRI angiograms. However, clinically asymptomatic vessel thrombosis is sometimes picked up by screening investigations or during routine imaging for other indications. Acute management of thrombosis and thromboembolism comprises a variety of approaches, including simple observation, treatment with unfractionated or low molecular weight heparin, as well as more aggressive interventions such as thrombolytic therapy or catheter-directed revascularization. Long-term follow-up is dependent on the underlying diagnosis. In the majority of infants, stabilization of the patients’ general condition and hemodynamics, which allows removal of indwelling catheters, renders long-term anticoagulation superfluous. Nevertheless, in certain types of congenital heart disease or inherited thrombophilia, long-term prophylaxis may be warranted. This review article focuses on pathophysiology, diagnosis, and acute and long-term management of thrombosis in critically ill term and preterm neonates.

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.

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.