Renal venous thrombosis in neonates: prothrombotic risk factors and long-term follow-up

An unusual cause of renal vein thrombosis in a newborn: COVID-19

There is no information on renal vein thrombosis induced by COVID-19 infection in a neonate. Few cases of renal vein thrombosis caused by COVID-19 infection have been reported in predominantly adult patients. On day 25 after birth, a newborn whose mother was infected with COVID-19 had renal vein thrombosis. We believed that our patient's renal vein thrombosis was caused by postnatal transmission of the COVID-19 infection that the mother had acquired during birth. The clinical and radiologic findings of these unusual renal complications in a neonate, as well as treatment options, are presented.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Incidence, Risk Factors, and Outcomes of Neonatal Renal Vein Thrombosis in Ontario: Population-Based Cohort Study

Background

There are limited data at a population level on the burden, risk factors, and long-term outcomes of neonatal renal vein thrombosis (nRVT). We conducted a population-based cohort study to understand the epidemiology and outcomes of nRVT over a 25-year period in Ontario.

Methods

Using linked administrative health databases, all hospitalized neonates ≤28 days born in Ontario between 1992 and 2016 with nRVT were identified. The primary outcome was to calculate the incidence of nRVT and trend over time in Ontario. We also determined the risk factors associated with nRVT as well as the risk of long-term outcomes after nRVT, including CKD, ESKD, all-cause mortality, and hypertension (HTN) compared with the healthy neonatal population without nRVT.

Results

The annual incidence rate of nRVT was 2.6 per 100,000 live births (n=85). Presence of respiratory distress syndrome (OR, 8.01; 95% CI, 4.90 to 13.1), congenital heart disease (OR, 9.1; 95% CI, 5.05 to 16.4), central venous catheterization (OR, 3.9; 95% CI, 1.89 to 7.93), maternal preeclampsia (OR, 2.8; 95% CI, 1.6 to 4.79), and maternal diabetes (OR, 2.36; 95% CI, 1.36 to 4.07) conferred the highest risk for nRVT. Over a median follow-up of 15 years and after adjusting for confounders, neonates with nRVT versus the comparator cohort had a 15.5-fold risk of CKD, HTN, or death (n=49 [58%] versus n=90,050 [3%]; 95% CI, 11.7 to 20.6); 12.3-fold increased risk of CKD or death (n=39 [46%] versus n=32,016 [1%]; 95% CI, 8.9 to 16.8); and a 15.7-fold increased risk of HTN (n=33 [39%] versus n=64,458 [2%]; 95% CI, 11.1 to 21.1). None of the nRVT cohort developed ESKD. The median time to composite outcome of CKD, HTN, or death was 11.1 years.

Conclusions

Patients with a history of nRVT remain at higher risk than the general population for long-term morbidity or mortality, indicating the need for long-term follow-up.

Spontaneous neonatal renal vein thrombosis, a known pathology without clear management guidelines: An overview

Renal vein thrombosis (RVT) was first described in 1837 by Rayer. Although tremendous progress has been achieved in the comprehension of its pathophysiology, its management remains controversial over 20 decades later. Therapeutic modalities vary from supportive measures alone to the utilization of thrombolytic agents whose protocols are derived from adult medicine. This review aims to show how difficult the treatment of RVT still is, especially with regard to the prognosis. The majority of affected neonates end with various renal complications (renal atrophy, dysfunction, hypertension, etc.). Like others, we suggest that simple unilateral RVT be managed conservatively, while thrombolytic agents may be attempted in unilateral RVT with extension to VCI and in bilateral RVT. Further studies are needed to reach appropriate consensual guidelines.

Approach to the Child with Hematuria

The causes of macroscopic and microscopic hematuria overlap; both are often caused by urinary tract infections or urethral/bladder irritation. Coexistent hypertension and proteinuria should prompt investigation for glomerular disease. The most common glomerulonephritis in children is postinfectious glomerulonephritis. In most patients, and especially with isolated microscopic hematuria, the diagnostic workup reveals no clear underlying cause. In those cases whereby a diagnosis is made, the most common causes of persistent microscopic hematuria are thin basement membrane nephropathy, immunoglobulin A nephropathy, or idiopathic hypercalciuria. Treatment and long-term prognosis varies with the underlying disease.

Lethal Renal Venous Thrombosis Complicating Dehydration in Infancy

A 3-month-old boy presented to hospital in cardiac arrest, dehydrated, with a blood sodium of 158.4 mmol/L. He had been febrile, not feeding normally and refusing fluids. Despite attempts at resuscitation with rehydration, he was declared dead. At autopsy, the kidneys were uniformly enlarged with thrombi within intraparenchymal tributaries of the renal veins bilaterally. Death was due to bilateral renal venous system thrombosis with hypernatremic dehydration. It is likely that the dehydration resulted both from increased requirements for fluid due to fever and from inadequate oral intake. Lethal renal venous thrombosis is a rare multifactorial condition that should be suspected in all infants with histories of hypernatremic dehydration with hypotension. Although there may be no obvious renal vein thrombosis at the time of dissection, microscopy may reveal intraparenchymal venous thromboses. As inherited prothrombotic states are associated with renal venous thrombosis, hematologic evaluation of immediate family members would be in order.

Spontaneous neonatal renal vein thromboses: Should we treat them all? A report of five cases and a literature review

Renal vein thrombosis (RVT) is a rare but well-known neonatal entity for which several therapeutic modalities are reported in the literature because of the lack of consensus management guidelines.

POPULATION AND METHODS

A retrospective study of the medical records of children managed between January 1990 and December 2013, and whose final diagnosis was RVT. The diagnosis was initially clinical and subsequently confirmed by the abdominal ultrasonography (AUS) and Doppler imaging if necessary. The abdominal CT scan was performed when the AUS finding led to the suspicion of RVT extension to the inferior vena cava (IVC). Each patient's birth parameters (birth weight [BW], birth length [BL], and head circumference [HC]) and modalities were recorded. The treatment modalities, the outcome at follow-up along with results of etiological screening were also recorded.

RESULTS

Five newborn infants were diagnosed as having unilateral RVT at the mean postnatal age of 3.8 days (range, 1-11 days). All presented with a classical triad associated nephromegaly, thrombocytopenia, and gross hematuria. Two patients had genetic thrombophilic risk factors (1 heterozygous Leiden factor V mutation in case 4, and Activated Protein C resistance in case 5). Two infants were managed conservatively, and the other three received antithrombotic treatment (recombinant tissue plasminogen activator and heparin). All five patients had a similar course, leading to non-functioning renal atrophy, despite aggressive thrombolytic therapy or conservative treatment.

CONCLUSION

We suggest that simple unilateral RVT be managed conservatively, while antithrombotic therapy may be attempted for unilateral RVT extending into the inferior vena cava and for bilateral RVT.

Anticoagulant Protein S Targets the Factor IXa Heparin-Binding Exosite to Prevent Thrombosis

OBJECTIVE

PS (protein S) is a plasma protein that directly inhibits the coagulation FIXa (factor IXa) in vitro. Because elevated FIXa is associated with increased risk of venous thromboembolism, it is important to establish how PS inhibits FIXa function in vivo. The goal of this study is to confirm direct binding of PS with FIXa in vivo, identify FIXa amino acid residues required for binding PS in vivo, and use an enzymatically active FIXa mutant that is unable to bind PS to measure the significance of PS-FIXa interaction in hemostasis.

APPROACH AND RESULTS

We demonstrate that PS inhibits FIXa in vivo by associating with the FIXa heparin-binding exosite. We used fluorescence tagging, immunohistochemistry, and protein-protein crosslinking to show in vivo interaction between FIXa and PS. Importantly, platelet colocalization required a direct interaction between the 2 proteins. FIXa and PS also coimmunoprecipitated from plasma, substantiating their interaction in a physiological milieu. PS binding to FIXa and PS inhibition of the intrinsic Xase complex required residues K132, K126, and R170 in the FIXa heparin-binding exosite. A double mutant, K132A/R170A, retained full activity but could not bind to PS. Crucially, Hemophilia B mice infused with FIXa K132A/R170A displayed an accelerated rate of fibrin clot formation compared with wild-type FIXa.

CONCLUSIONS

Our findings establish PS as an important in vivo inhibitor of FIXa. Disruption of the interaction between PS and FIXa causes an increased rate of thrombus formation in mice. This newly discovered function of PS implies an unexploited target for antithrombotic therapeutics.

Early onset of abdominal venous thrombosis in a newborn with homozygous type II heparin-binding site antithrombin deficiency

: The overall incidence of thromboembolic events in the neonatal period is 5 per 100 000 births, wherein more than 40% of all such manifestations are symptomatic renal vein thromboses. We describe the case of a newborn female who developed extensive thrombosis, which filled the inferior vena cava and renal vein and was diagnosed in the first weeks of life. A homozygous type II heparin-binding site antithrombin deficiency (c. 391C>T, p. Leu131Phe) was detected in the background. Despite the timely diagnosis and appropriate treatment, clinical signs of renal insufficiency, because of left kidney atrophy and arterial hypertension, were observed. Our case demonstrates the seriousness of the consequences arising after early onset of venous thrombosis caused by homozygous type II heparin-binding site antithrombin deficiency. In addition to prompt diagnosis, of huge importance is the determination of inherited thrombophilia, as it significantly affects therapeutic treatment and indicates that long-term follow-up is mandatory.

Thrombosis of the Abdominal Veins in Childhood

Abdominal venous thrombosis is a rare form of venous thromboembolic disease in children. While mortality rates are low, a significant proportion of affected children may suffer long-term morbidity. Additionally, given the infrequency of these thrombi, there is lack of stringent research data and evidence-based treatment guidelines. Nonetheless, pediatric hematologists and other subspecialists are likely to encounter these problems in practice. This review is therefore intended to provide a useful guide on the clinical diagnosis and management of children with these rare forms of venous thromboembolic disease. Herein, we will thus appraise the current knowledge regarding major forms of abdominal venous thrombosis in children. The discussion will focus on the epidemiology, presentation, diagnosis, management, and outcomes of (1) inferior vena cava, (2) portal, (3) mesenteric, (4) hepatic, and (5) renal vein thrombosis.

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.

Lipoprotein (a) as a cause of cardiovascular disease: insights from epidemiology, genetics, and biology

Human epidemiologic and genetic evidence using the Mendelian randomization approach in large-scale studies now strongly supports that elevated lipoprotein (a) [Lp(a)] is a causal risk factor for cardiovascular disease, that is, for myocardial infarction, atherosclerotic stenosis, and aortic valve stenosis. The Mendelian randomization approach used to infer causality is generally not affected by confounding and reverse causation, the major problems of observational epidemiology. This approach is particularly valuable to study causality of Lp(a), as single genetic variants exist that explain 27-28% of all variation in plasma Lp(a). The most important genetic variant likely is the kringle IV type 2 (KIV-2) copy number variant, as the apo(a) product of this variant influences fibrinolysis and thereby thrombosis, as opposed to the Lp(a) particle per se. We speculate that the physiological role of KIV-2 in Lp(a) could be through wound healing during childbirth, infections, and injury, a role that, in addition, could lead to more blood clots promoting stenosis of arteries and the aortic valve, and myocardial infarction. Randomized placebo-controlled trials of Lp(a) reduction in individuals with very high concentrations to reduce cardiovascular disease are awaited. Recent genetic evidence documents elevated Lp(a) as a cause of myocardial infarction, atherosclerotic stenosis, and aortic valve stenosis.

Renal vascular thrombosis in the newborn

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

Proteinuria and hematuria in the neonate

PURPOSE OF REVIEW

Neonatal proteinuria and hematuria while not common can have potentially devastating consequences if left undiagnosed and untreated. It is important to distinguish between inherited and acquired causes of proteinuria to initiate appropriate and timely treatment. With regards to hematuria, it is critical to identify true hematuria from pseudo-hematuria to balance between thorough investigation and unnecessary laboratory work up. This review provides an overview of the common causes of hematuria and proteinuria in a neonate.

RECENT FINDINGS

The identification of genetic mutations in nephrotic syndrome has improved our understanding of the role of various proteins that play an important role in maintaining the glomerular filtration barrier. With the advancement in our ability to provide care for extreme premature neonates, the incidence of acute kidney injury has increased in these neonates along with proteinuria and hematuria.

SUMMARY

Persistent proteinuria after neonatal acute kidney injury would be of interest in regards to the risk of developing future chronic kidney disease and hypertension.

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.

Active malignancy in patients with renal vein thrombosis: influence upon clinical course and survival

BACKGROUND

Renal vein thrombosis (RVT) is a rare event with myriad clinical manifestations. Published experience regarding the clinical course and management of RVT in patients beyond the neonatal period is limited to case reports and small case series.

METHODS

A multicenter retrospective review of consecutive admitted patients with diagnosed RVT between January 2000 and May 2015 at three different university hospitals.

RESULTS

Thirty-nine patients (53.8 % men and 46.2 % women) were included. Median age was 58 years. Malignancy (n = 19, 48.7 %), nephrotic syndrome (n = 8, 20.5 %) and infection (n = 5, 12.8 %), were the most common underlying conditions. Compared to non-cancer patients, patients with active cancer tended to be significantly older (mean age 63 ± 18 vs. 37 ± 22 years, P = 0.001) and presented with non-acute symptoms (P = 0.01) and unrevealing physical findings (P = 0.02). Thrombosis extension beyond the renal vein occurred in 69.2 % of cases and was more common in cancer patients (P = 0.001). Anticoagulation therapy was administered in 71.8 % of patients leading to resolution of thrombus in most cases (30/32 patients, 94 %) during follow-up evaluation. There were six recurrent thrombotic events during a mean follow-up of 35 ± 43 months. Nine patients (28 %) died during follow-up, all of them with malignancy.

CONCLUSION

Active cancer is the most common cause of RVT and should be excluded when RVT is diagnosed. Clinical course of RVT in cancer patients is more indolent and diagnosis requires high index of suspicion. Survival rates are governed by the presence of malignancy.

Thromboembolism and anticoagulation management in the preterm infant

The incidence of preterm thromboembolism has been increasing due to advances in diagnostic imaging which allow better detection of thrombi in sick preterm infants. At the same time, improvement in neonatal intensive care unit supportive care has increased the number of surviving and living preterm infants with thromboembolic risk factors. Disruption in the fine balance of hemostasis with potential risk factors, specifically septicemia and indwelling catheters, increase the occurrence of thromboembolic events. Treatment strategies in preterm infants are challenging due to limited data.

Neonatal renal vein thrombosis: role of anticoagulation and thrombolysis--an institutional review

Neonatal renal vein thrombosis (NRVT) is a rare thromboembolic complication in the neonatal period, and sequelae from renal dysfunction can cause significant morbidity. The authors retrospectively reviewed 10 patients with NRVT treated at their institution. The majority of the cohort were male (n = 9), preterm (n = 6), and had unilateral NRVT (n = 6). Six patients received thrombolysis and/or anticoagulation, and 4 patients received supportive care only. Two of the 6 patients treated with anticoagulation who had bilateral NRVT and anuria received thrombolysis with low-dose tissue plasminogen activator. Thrombolysis was not associated with any major adverse events, and both patients had marked improvement of renal function. Eight patients subsequently developed renal atrophy (3 received anticoagulation, 2 received thrombolysis with anticoagulation, and 3 received supportive care). Anticoagulation/thrombolysis did not appear to prevent renal atrophy. The role of thrombolysis needs to be further studied and considered in the setting of bilateral NRVT and acute renal failure.

Thrombosis in the Neonatal Intensive Care Unit

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

Extensive Thrombosis of the Inferior Vena Cava and Left Renal Vein in a Neonate

Antenatal renal vein thrombosis is a rarely described diagnostic finding, with variable consequences on kidney function. We present the case of an affected fetus, born at 35-week gestation, with intrauterine oligohydramnios and two small kidneys. A renal ultrasound carried out after birth confirmed the presence of prenatal abnormalities. Renal vein thrombosis was not diagnosed at the time. The baby died 20 days later of kidney failure, metabolic acidosis, and polypnea with severe hypotrophy. Autopsy revealed atrophied kidneys and adrenal glands. The vena cava had thrombosis occupying most of its length. The right renal vein was normal, while the left renal vein was threadlike and not permeable. Histologically, there was necrosis of the left adrenal gland with asymmetrical bilateral renal impairment and signs of ischemic and hemorrhagic lesions. A review of thrombophilia was carried out and a heterozygous mutation in Factor V was found in both the mother and the child.

Manifestations and clinical impact of pediatric inherited thrombophilia

The etiology of pediatric venous thromboembolic disease (VTE) is multifactorial, and in most children, 1 or more clinical risk factors are present. In addition, inherited thrombophilic disorders contribute to the development of pediatric VTE. In this review, the role of inherited thrombophilic disorders in the development of pediatric VTE, as well as the benefits and limitations of thrombophilia testing, will be discussed.

Neonatal haemostasis and the management of neonatal thrombosis

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

Central retinal vein obstruction in a neonate occurring during laser photocoagulation treatment for retinopathy of prematurity

A premature infant who developed central retinal vein obstruction in one eye during laser therapy for high-risk prethreshold retinopathy of prematurity is described. Systemic investigations were done to detect the cause of such an acute and unreported episode. Acquired deficiency of protein C levels was detected. Premature infants are at risk of thromboembolic episodes due to deranged hematological parameters. Acquired protein C deficiency possibly precipitated acute retinal vein occlusion during laser therapy in this infant. Intravitreal bevacizumab was used successfully to treat the episode of retinal venous occlusion. Retinal vein obstruction during laser treatment for retinopathy of prematurity is reported for the first time.

Venous thromboembolism at uncommon sites in neonates and children

We retrospectively analyzed the data of 24 children (whereof 11 neonates), with non-central venous line-related and nonmalignancy-related venous thromboembolism (VTE) at uncommon sites, referred to our Unit from January 1999 to January 2012. Thirty patients who also suffered deep vein thrombosis, but in upper/low extremities, were not included in the analysis. The location of rare site VTE was: portal (n=7), mesenteric (n=2) and left facial vein (n=1), spleen (n=3), lung (n=3), whereas 10 neonates developed renal venous thrombosis. The majority of patients (91.7%) had at least 1 risk factor for thrombosis. Identified thrombophilic factors were: antiphospholipid antibodies (n=2), FV Leiden heterozygosity (n=6), MTHFR C677T homozygosity (n=4), protein S deficiency (n=2), whereas all neonates had age-related low levels of protein C and protein S. All but 6 patients received low-molecular-weight heparin, followed by warfarin in 55% of cases, for 3 to 6 months. Prolonged anticoagulation was applied in selected cases. During a median follow-up period of 6 years, the clinical outcome was: full recovery in 15 patients, evolution to both chronic portal hypertension and esophageal varices in 2 children, and progression to renal failure in 7 of 10 neonates. Neonates are greatly vulnerable to complications after VTE at uncommon sites, particularly renal. Future multicentre long-term studies on neonatal and pediatric VTE at unusual sites are considered worthwhile.

Successful management of neonatal renal venous thrombosis

Renal vein thrombosis is the most common vascular condition involving the newborn kidney and it can result in severe renal damage. We report a newborn with renal vein thrombosis treated with continuous infusion of unfractionated heparin who had normal total renal function after 3 years of follow up, despite reduction of the functional contribution of the affected kidney.

Prenatal renal vein thrombosis in dichorionic twin pregnancy

BACKGROUND

Prenatal renal vein thrombosis is a rarely described diagnostic finding. The etiology is unclear in the majority of cases, although thrombophilia was found in some affected fetuses. Precise ultrasound scan can improve detection rate of neonatal thrombosis due to characteristic findings.

CASE REPORT

We present the unusual case of a dichorionic twin pregnancy in 31 weeks of gestation with one affected fetus, showing already intrauterine a bilaterally enlarged kidney and absence of renal venous flow. Additionally, the fetus showed signs of circulatory compromise and fetal distress, while dichorionic male co-twin was healthy. The postnatal thrombophilia investigations revealed a heterozygous factor V Leiden mutation.

CONCLUSION

Fetal renal vein thrombosis may occur bilateral and may also involve the inferior vena cava. Rapid deterioration of fetal condition, abnormal fetal Doppler, appearance of hydrops fetalis, may accompany fetal venous thrombosis. By color Doppler flow mapping abnormal arterial and absent venous perfusion of the affected kidney may be demonstrated in addition.

Unusual Presentation of Renal Vein Thrombosis in a Preterm Infant

Neonatal renal vein thrombosis is the most common vascular condition in the newborn kidney, which could lead to serious complication in infants undergoing intensive care. In this study, we report the case of a preterm infant with left renal vein and inferior vena cava thrombosis, presented with gross hematuria, thrombocytopenia, transient hypertension, and adrenal hemorrhage. Supportive care was offered instead of heparin therapy or thrombolytic agents. In conclusion, our case teaches that, despite the lack of a clinically obvious shock event, renal vein thrombosis should be considered in a macrohematuric newborn without renal failure.

Renal failure due to renal vein thrombosis in a fetus with growth restriction and thrombophilia

We report a case of renal vein thrombosis diagnosed at 27 weeks of gestation in a dichorionic twin pregnancy. The left kidney of one fetus was hyperechoic and enlarged with echoic streaks following the direction of interlobular veins and the loss of corticomedullary differentiation. In the following weeks, left kidney became smaller and echoic, and Doppler examination showed no flow in both artery and vein. The right kidney had totally normal appearance in the beginning, but it became enlarged and hyperechoic, and progressed into a small echoic kidney with no flow in artery and vein. In the postnatal ultrasound examination, both kidneys appeared hyperechoic with no vascularization in the hilum region. There was thrombosis in arteries and veins of both kidneys, as well as in the inferior vena cava. The investigation for thrombophilia resulted with the combined presence of heterozygote mutation in factor V Leiden and prothrombin 20210 genes.

Intrauterine upper limb ischemia: an unusual presentation of fetal thrombophilia-a case report and review of the literature

Upper limb ischemia presenting in neonatal period is extremely rare. Moreover, presenting newborn with evidence of intrauterine upper limb vascular occlusion is even rarer. It needs prompt intervention to restore perfusion and avoid morbidity. We present a newborn with right upper limb brachial artery thrombosis causing ischemia that was noted at birth and appeared later to be homozygous for factor V Leiden and glycoprotein IIIa with no other identifiable risk factors. In this report, we present the case, its successful medical management, proper counseling, and review of the literature. We recommend investigating the neonates and their parents for thrombophilia mutations when they present with unusual vascular occlusion site as newborns.

What is the safe approach for neonatal hypernatremic dehydration? A retrospective study from a neonatal intensive care unit

OBJECTIVES

The aims of this study were to evaluate the prevalence, complications, and mortality of hypernatremic dehydration in neonates and to compare the effect of correction rate at 48 hours on mortality and on neurological outcome in the short term.

METHODS

This retrospective study was conducted between January 2007 and 2011 in the neonatal intensive care unit. Term neonates were included. The patients were grouped as follows: group 1 = 150 to 160 mmol/L, group 2 = 161 to 170 mmol/L and group 3 = 171 to 189 mmol/L.

RESULTS

Among 4280 neonates, 81 cases (1.8%) had hypernatremic dehydration. Groups 1, 2, and 3 consisted of 55, 23, and 3 patients, respectively. Mortality rates were as follows: 3.6%, 17.3%, and 66.6%. Mean serum sodium (Na) correction rates at 0 to 24 hours and 24 to 48 hours were 0.48 ± 0.2 versus 0.38 ± 0.31 mmol/L per hour (group 1) and 0.49 ± 0.21 versus 0.52 ± 0.28 mmol/L per hour (group 2), respectively. In 32 patients (58.1%) from group 1 and in 13 patients (56.5%) from group 2, correction rate of 0.5 mmol/L per hour or less was achieved. Twenty-two patients developed convulsions, which was the most common complication during therapy. Serum Na greater than 160 mmol/L at admission (odds ratio, 1.9; 95% confidence interval, 1.3-3.7) and serum Na correction rate of greater than 0.5 mmol/L per hour (odds ratio, 4.3; 95% confidence interval, 1.2-6.5) were independent risk factors for death or convulsion. There was a significant difference between groups 1 and 2 in Denver Developmental Screening Test II results (64.1% vs 30.7 %, P = 0.001).

CONCLUSION

Hypernatremic dehydration is an important problem that should be managed properly to avoid adverse outcomes.

Characteristics of abdominal vein thrombosis in children and adults

The demographic and clinical characteristics of adults and children with lower extremity deep-vein thrombosis and/or pulmonary embolism (LE DVT/PE) may differ from those with abdominal vein thrombosis (abdominal VT). Abdominal VT can be a presenting sign of an underlying prothrombotic state, and its presence in the setting of known disease might have prognostic implications different from LE DVT/PE. This study describes clinical presentations of abdominal VT compared to LE DVT/PE in adults and children. We analysed prospectively-collected data from consecutive consenting patients enrolled in one of seven Centers for Disease Control and Prevention (CDC) funded Thrombosis and Hemostasis Network Centers from August 2003 to April 2011 to compare the demographic and clinical characteristics of adults and children with abdominal VT. Both adults and children with abdominal VT tended to be younger and have a lower body mass index (BMI) than those with LE DVT/PE. Of patients with abdominal VT, children were more likely to have inferior vena cava (IVC) thrombosis than adults. For adults with venous thromboembolism (VTE), relatively more women had abdominal VT than LE DVT/PE, while the proportions with LE DVT/PE and abdominal VT by sex were similar in children. Children with abdominal VT were more likely to have diagnosed inherited thrombophilia, while trauma was more common in children with LE DVT/PE. In conclusion, both children and adults with abdominal VT were younger with a lower BMI than those with LE DVT/PE. Significant differences exist between children and adults in respect to abdominal VT compared to LE DVT/PE.

Abdominal thromboses of splanchnic, renal and ovarian veins

Thromboses of abdominal veins outside the iliac-caval axis are rare but clinically relevant. Early deaths after splanchnic vein thrombosis occur in 5-30% of cases. Sequelae can be liver failure or bowel infarction after splanchnic vein thrombosis, renal insufficiency after renal vein thrombosis, ovarian infarction after ovarian vein thrombosis. Local cancer or infections are rare in Budd-Chiari syndrome, and common for other sites. Inherited thrombophilia is detected in 30-50% of patients. Myeloproliferative neoplasms are the main cause of splanchnic vein thrombosis: 20-50% of patients have an overt myeloproliferative neoplasm and/or carry the molecular marker JAK2 V617F. Renal vein thrombosis is closely related to nephrotic syndrome; finally, ovarian vein thrombosis can complicate puerperium. Heparin is used for acute treatment, sometimes in conjunction with systemic or local thrombolysis. Vitamin K-antagonists are recommended for 3-6 months, and long-term in patients with Budd-Chiari syndrome, unprovoked splanchnic vein thrombosis, or renal vein thrombosis with a permanent prothrombotic state such as nephrotic syndrome.

Antithrombotic therapy in neonates and children: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

Neonates and children differ from adults in physiology, pharmacologic responses to drugs, epidemiology, and long-term consequences of thrombosis. This guideline addresses optimal strategies for the management of thrombosis in neonates and children.

METHODS

The methods of this guideline follow those described in the Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines.

RESULTS

We suggest that where possible, pediatric hematologists with experience in thromboembolism manage pediatric patients with thromboembolism (Grade 2C). When this is not possible, we suggest a combination of a neonatologist/pediatrician and adult hematologist supported by consultation with an experienced pediatric hematologist (Grade 2C). We suggest that therapeutic unfractionated heparin in children is titrated to achieve a target anti-Xa range of 0.35 to 0.7 units/mL or an activated partial thromboplastin time range that correlates to this anti-Xa range or to a protamine titration range of 0.2 to 0.4 units/mL (Grade 2C). For neonates and children receiving either daily or bid therapeutic low-molecular-weight heparin, we suggest that the drug be monitored to a target range of 0.5 to 1.0 units/mL in a sample taken 4 to 6 h after subcutaneous injection or, alternatively, 0.5 to 0.8 units/mL in a sample taken 2 to 6 h after subcutaneous injection (Grade 2C).

CONCLUSIONS

The evidence supporting most recommendations for antithrombotic therapy in neonates and children remains weak. Studies addressing appropriate drug target ranges and monitoring requirements are urgently required in addition to site- and clinical situation-specific thrombosis management strategies.

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.

Thrombophilia testing in neonates and infants with thrombosis

In neonates and infants with idiopathic venous thrombosis (VTE) and in pediatric populations in which thromboses were associated with medical diseases, inherited thrombophilia (IT) have been described as risk factors. Follow-up data for VTE recurrence in neonates suggest a recurrence rate between 3% in provoked and 21% in idiopathic VTE. Apart from underlying medical conditions, recently reported systematic reviews on pediatric VTE have shown significant associations between factor V G1691A, factor II G20210A, and deficiencies of protein C, protein S and antithrombin, even more pronounced when combined IT were involved. Independent from the age at first VTE onset, the pooled odds ratios (OR: single IT) for VTE ranged from 2.4 for the factor II G20210A mutation to 9.4 in neonates and infants with antithrombin deficiency. The pooled OR for persistent antiphospholipid antibodies/lupus anticoagulants was 4.9 for pediatric patients with venous VTE. The factor II G20210A mutation (OR: 2.1), and deficiencies of protein C (OR: 2.4), S (OR: 3.1) and antithrombin (OR: 3.0) also played a significant role at recurrence. Based on these data, screening and treatment algorithms must be discussed.

Neonatal renal vein thrombosis

Neonatal renal vein thrombosis (RVT) continues to pose significant challenges for pediatric hematologists and nephrologists. The precise mechanism for the onset and propagation of renal thrombosis within the neonatal population is unclear, but there is suggestion that acquired and/or inherited thrombophilia traits may increase the risk for renal thromboembolic disease during the newborn period. This review summarizes the most recent studies of neonatal RVT, examining its most common features, the prevalence of acquired and inherited prothrombotic risk factors among these patients, and evaluates their short and long term renal and thrombotic outcomes as they may relate to these risk factors. Although there is some consensus regarding the management of neonatal RVT, the most recent antithrombotic therapy guidelines for the management of childhood thrombosis do not provide a risk-based algorithm for the acute management of RVT among newborns with hereditary prothrombotic disorders. Whereas neonatal RVT is not a condition associated with a high mortality rate, it is associated with significant morbidity due to renal impairment. Recent evidence to evaluate the effects of heparin-based anticoagulation and thrombolytic therapy on the long term renal function of these patients has yielded conflicting results. Long term cohort studies and randomized trials may be helpful to clarify the impact of acute versus prolonged antithrombotic therapy for reducing the morbidity that is associated with neonatal RVT.

[Neonatal renal venous thrombosis: the recent experience of Robert-Debré hospital]

Neonatal renal venous thrombosis (NRVT) is a rare disease, with variable consequences on kidney function. We report a retrospective study of 9 newborns with NRVT admitted to our hospital from 1996 to 2005. The median age at diagnosis was 2 days (range, 1-10 days). In 7 patients, diagnosis was suspected based on one classical clinical or biological sign and was confirmed by ultrasound. Seven newborns had at least one known obstetrical or neonatal risk factor. NRVT was unilateral in three cases, was bilateral in 6 cases, and was associated with inferior vena cava thrombosis in 5 patients, with surrenal hemorrhage in 3 patients. Three patients did not receive specific treatment. The median delay between diagnosis and specific treatment was 20 h (range, 3-36 h). Three patients were treated by fibrinolysis, including 2 with bilateral NRVT, 2 newborns received heparins, and 1 patient was treated with a vitamin K antagonist. With a median evaluation time of 5 years and 2 months for 6 patients, 5 patients recovered their kidney function completely and the 6th child has moderate renal failure. It seems illusory to wait for randomized control studies to appreciate the potential long-term benefit of treatments on kidney function after a NRVT, whose bilateral forms appear to be more severe. A case-by-case approach appears better adapted. These results reinforce recommendations that suggest an early pediatric nephrologic follow-up for all newborns with a NRVT.

Sonography of renal venous thrombosis in neonates and infants: can we predict outcome?

BACKGROUND

The relationship between sonographic features of renal venous thrombosis (RVT) and outcome has not been described in a large series of patients.

OBJECTIVE

To analyze sonographic findings of RVT and their evolution in a large series of patients and to attempt to identify features that might predict outcome.

MATERIALS AND METHODS

Retrospective analysis of sonograms and medical records of neonates and infants diagnosed with RVT during the period 1998-2007.

RESULTS

Of 22 children (mean age: 3 days; age range: 0-107 days), RVT was bilateral in 12. Of 34 affected kidneys, thrombus in the main renal vein was seen in 17 and typical RVT sonographic findings without main renal vein thrombus were seen in the remaining 17. All children had US follow-up (range: 0.6-97.2 months). Three children with bilateral RVT died. Nine kidneys atrophied. Imaging findings associated with subsequent kidney atrophy included markedly reduced perfusion at diagnosis, subcapsular collections, patchy cortical echotexture and profoundly hypoechoic and irregular renal pyramids. Six patients (eight kidneys) presented with renal calcifications on initial sonogram before 7 days of life, suggesting antenatal RVT.

CONCLUSION

Sonography is useful in neonatal and early infant RVT and might help predict renal atrophy. Antenatal RVT appears to be relatively common.