Neonatal Renal Vein Thrombosis Research Articles

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

Neonatal renal vein thrombosis (NRVT) is a rare condition with little data available. We retrospectively analyzed newborns diagnosed with NRVT admitted to3 pediatric nephrology units in Paris from 2005 to 2020. Twenty-seven patients were analyzed (male = 59%). The median age at diagnosis was2.5days (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 and4 (16%) received fibrinolysis. Median duration of treatment was 8weeks (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 5.7years (3years-9.9years), 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 in2(8%). 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.

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. 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. 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. 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.

Thrombophlebitis hiding under a KILT \u2013 case report on 40\u2009years long-term follow-up of neonatal renal vein thrombosis

BackgroundNeonatal renal vein thrombosis is a recognised cause of renal and inferior caval vein atresia (IVCA). However, the long-term impact of the condition is underrecognized with a high burden of morbidity for the patient, especially in adulthood. IVCA has been shown to be an independent risk factor for deep venous thrombosis (DVT) with a high risk of recurrence. The acronym KILT for kidney and inferior vena cava anomaly with leg thrombosis summarizes the pathological situation.Case presentationWe present the case of a 40-year-old patient with pain in the right lower limb resulting from acute thrombophlebitis. No risk factors could be identified. His history was remarkable with two episodes of deep venous thrombosis first of the left, then the right leg 22 years earlier; at that time also, no risk factor was identified. Because of the idiopathic character of that thrombosis, the patient remained on long-term anticoagulation with phenprocoumon. The present thrombophlebitis occurred while the INR was not therapeutic in the preceding weeks. A CT with contrast showed atresia of the inferior vena cava and of the right kidney, and presence of numerous collaterals. A thorough medical history revealed a renal vein thrombosis as a neonate. Anticoagulation was intensified, and stent placement became necessary after a further 2 years.Discussion and conclusionsKILT syndrome is a rare but underrecognized condition. Complications may arise in young adulthood only, and it is of prime importance to instruct parents of the pediatric patient of the possible consequences of renal vein thrombosis and to assure guidance from the treating physicians throughout adulthood. Diagnosis of IVCA is by CT with contrast or by MRI, and lifelong anticoagulation may be necessary. Since the KILT syndrome is widely underdiagnosed, we challenge the clinicians to keep it in mind when confronted with thrombophlebitis or thrombosis of the young, male and with no other identifiable risk factors for deep vein thrombosis.

Sequential sonographic features in neonatal renal vein thrombosis.

Renal vein thrombosis in newborns is a rare but serious and acute disease. Clinical representations of RVT can vary from discrete symptoms to life-threatening conditions. Therefore imaging, and in particular sonography, plays an important role in the diagnosis of RVT in neonates. Gray-scale, color and spectral/power Doppler ultrasound are all used in the diagnosis of RVT. We present retrospective sequential ultrasonic imaging of three patients (two term and one preterm infant) with findings characteristic of RVT. Initial ultrasound diagnostic features include: renal enlargement, echogenic medullary streaks, lack of the flow pattern characteristic of arcuate vessels and subsequently loss of corticomedullary differentiation, reduced echogenicity around pyramids and echogenic band at the extreme apex of the pyramid. Higher resistance index or less pulsatile venous flow on the affected kidney are helpful Doppler signs. Knowledge and identification of specific features of each phase of the evolution of RTV seems essential to prompt diagnosis. We would like to highlight the evolution of specific sonographic features in each subsequent phase of RVT.

Neonatal renal vein thrombosis: Role of anticoagulation and thrombolysis—An institutional review

ABSTRACTNeonatal 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.

Antenatal Bilateral Renal Vein Thrombosis with Combined Protein S and C Deficiency

In neonates, renal vein thrombosis (RVT) is the second most common thrombosis.We report a case of antenatal bilateral RVT and we review the optimal therapeutic approaches. I, a male newborn was admitted in the Neonatal Intensive Care Unit of the Center for Maternity and Neonatology of Tunis (CMNT) for respiratory distress and gross hematuria. Initial laboratory work demonstrated renal impairment and Doppler renal ultrasound confirmed the diagnosis of bilateral RVT. Thrombophilia evaluation found a combined protein C and S deficiency. Thrombolysis was started with tissue plasminogen factor in association to anticoagulation with unfractionated heparin. Renal vein thrombosis in neonates is a rare condition with a high morbidity rate. Thrombotic conditions may be associated with more severe clinical presentations. Currently, there is a lack of consensus concerning the management of RVT.

Neonatal renal venous and arterial thrombosis

Renal vein thrombosis (RVT) is one of the more common forms of neonatal thrombosis accounting for 15-20% of systemic thromboembolism[1,2]. A median age at presentation of 2-3 days have been reported [1,3], with unilateral and bilateral involvement of renal vein in 89-72% and 28-11% of cases, respectively[4,5]. The clinical presentation of RVT consists of increased kidney size, macroor microhematuria, reduced urine output with some degree of renal failure and thrombocytopenia. RVT in neonates is a multifactorial disease and it was associated with coagulopathy, maternal diabetes, birth asphyxia, sepsis, placement of central venous lines (CVL) and hereditary thrombophilic factors[5,6]. In specific, FV 1691G>A mutation and elevated Lp(a) concentrations are independent risk factors for the development of RVT in neonates. In non-CVL-related RVT, thrombus formation occurs in the small vessels of the kidney and may extend into the renal vein and inferior vena cava. In the neonates with CVL-related RVT, the thrombus most likely formed first in the vessel adjacent to the CVL and then extended into the kidney[4]. Renal ultrasonography shows unior bilateral kidney enlargement with loss of cortico-medullary differentiation and reduced or absent flow in renal vein[7]. Long-term functional complications include renal insufficiency, renal tubular dysfunction and hypertension in up to 30% of patients[1,8]. Controlled data on appropriate clinical management of neonatal RVT are lacking and recommendations of its treatment are based on low quality evidence. Current guidelines suggest for unilateral RVT in the absence of renal impairment or extension into the inferior vena cava, either 1) supportive care with radiologic monitoring for extension of thrombosis or 2) anticoagulation with unfractionated heparin (UFH)/ low-molecolar-weight heparin (LMWH) in therapeutic doses rather than no therapy[9]. For unilateral RVT that extends into the inferior vena cava, anticoagulation with UFH/LMWH for a total duration of between 6 weeks and 3 months is suggested[9]. For bilateral RVT with evidence of renal impairment, anticoagulation with UFH/LMWH or initial thrombolytic therapy with tissue plasminogen activator followed by anticoagulation with UFH/LMWH is suggested[9]. Renal artery thrombosis (RAT) in the neonate is far less common than RVT, and there is little information about its incidence. It is associated with umbilical catheters, patent ductus arteriosus and hereditary thrombophilia [10,11]. The clinical presentation is rather silent and renal ultrasound findings can be minimal unless Doppler imaging is used. The outcome of the affected kidneys is poor with common global atrophy. For neonates with a peripheral arterial catheter-related thrombosis, immediate removal of the catheter and UFH anticoagulation with or without thrombolysis or surgical thrombectomy and microvascular repair with subsequent heparin therapy are suggested[9].

Renal venous thrombosis in neonates.

Neonatal renal vein thrombosis (RVT) is associated with potentially serious morbidities. Almost 80% of cases of RVT present within the first postnatal month. The most common risk factors for RVT are birth asphyxia/ in utero fetal distress, being the infant of a diabetic mother, volume contraction and coagulation abnormalities. Thrombus formation may be initiated by vascular injury, diminished vascular flow, increased blood viscosity, hyperosmolality or underlying thrombophilia. The classic triad of RVT includes gross hematuria, flank mass (unilateral or bilateral enlargement of kidneys) and thrombocytopenia. Laboratory tests may reveal hematuria, proteinuria, polycythemia, hemolytic anemia, thrombocytopenia and possibly acute kidney injury. The etiology for a hypercoagulable state should be investigated. Renal ultrasound with Doppler may show increased size of the affected kidney, increased echogenicity and loss of corticomedullary differentiation. Renal venography remains the gold standard for the diagnosis of RVT. Other causes of renal enlargement must be considered. Supportive treatment includes correction of fluid and electrolyte disturbances and treatment of infection and underlying pathophysiologic abnormalities. Use of unfractionated heparin (UFH) or low molecular weight heparin (LMWH) should be considered if there is evidence of disseminated intravascular coagulation. Conventional anticoagulants may attenuate hypercoagulability and decrease the risk for thrombus progression and embolism. Surgery is rarely indicated unless there is bilateral involvement with involvement of the IVC. RVT carries the risk of hypertension and chronic kidney disease.

Successful surgical thrombectomy for neonatal IVC and bilateral renal vein thrombosis

We propose that renal salvage is possible in neonatal inferior vena cava (IVC) and bilateral renal vein thrombosis utilizing early surgical intervention. Management of bilateral renal vein thrombosis with renal impairment typically includes anti-coagulation and thrombolytic therapy. We report a case of a five day-old premature female, found to have bilateral renal vein thrombosis that had propagated up the IVC, associated with anuric renal failure. Peak BUN/creatinine was 52/4 at day of life 5, with a peak of 90/7.4 at day of life 10. After a failed attempt at intravenous thrombolytic therapy, thrombectomy was performed for the IVC as well as both renal veins. The patient urinated by post-operative day 2. Function improved daily, with creatinine stabilizing at 0.4 mg/dL by one month. Serial ultrasounds showed persistent patency of the IVC and bilateral renal veins. The patient was heterozygous for the Factor V Leiden mutation and pathology demonstrated evidence of placental thrombosis. We have shown that neonatal anuric renal failure secondary to bilateral renal vein thrombosis can be successfully managed with early surgical thrombectomy without the need for nephrectomy. Restoration of renal function after surgical thrombectomy in this patient illustrates the potential reversibility of acute renal failure even in severe cases.

Current Reviews on Renal Vein Thrombosis in Neonates

Neonatal renal vein thrombosis (NRVT) is a complication that occurs in newborns with various underlying risk factors. Various modes of therapies, including anticoagulation and fibrinolytic therapies have been reported with anecdotal success. Due to a lack of prospective controlled trials, there is currently no evidence-based guideline available for the treatment of neonates with renal vein thrombosis. The clinical features, diagnosis and current approach to management of neonatal renal vein thrombosis are reviewed in this chapter. Keywords: Pediatrics, neonatal, renal vein thrombosis.

Neonatal renal vein thrombosis and prothrombotic risk

A case of extensive deep venous thrombosis in a four a day old infant was presented. Unusually this patient was shown to be heterozygous for three thrombophilia genes; Factor V Leiden, prothrombin and antithrombin gene mutations, the latter being novel. There are no randomized controlled trials to guide management in deep venous thrombosis in the newborn but knowledge of the prothrombotic risk factors may help direct treatment.

Successful thrombolysis of neonatal bilateral renal vein thrombosis originating in the IVC

We describe a case of inferior vena cava thrombosis (IVC) leading to bilateral renal vein thrombosis and renal failure in a neonate, which was successfully treated by thrombolysis. A male neonate, born at term by vaginal delivery (Apgar score 9–10–10) and weighing 4210 g at birth after a normal pregnancy, presented at 9 days of age due to failure to thrive and gross haematuria. At admission the child weighed 4200 g and appeared to be dehydrated. He was anuric with a serum creatinine of 222 μmol/L (reference 14–37 μmol/L), severe metabolic acidosis and respiratory difficulties. He had a palpable abdominal mass on the left side of the abdomen. Ultrasound examination showed enlarged hyperechogenic kidneys, especially on the left side. The renal veins and IVC could not be visualised. Magnetic resonance (MR) angiography revealed thrombosis of the IVC from the bifurcation up to the hepatic veins (Fig. 1a, b) and extending into both renal veins. There was no evidence of adrenal haemorrhage. Treatment with warfarin (Waran; Nycomed, Zurich, Switzerland) was initiated (Fig. 1c), and systemic lowmolecular weight heparin (LMWH) (dalteparin sodium, Fragmin; Pfizer, New York, NY). The dose was adjusted by following levels of anti-Factor Xa geared at 0.5–1.0 kIE/L. Because the ultrasound did not show any change in the size of the thrombus, warfarin was discontinued, and local fibrinolysis was initiated [1, 2]. An angio-catheter was inserted into the occluding thrombus in the IVC, and continuous infusion of recombinant tissue plasminogen activator (rt-PA) (Actilyse; Boehringer, Ingelheim, Germany) was administered at 0.1 mg/kg/hour. The rt-PA treatment was monitored by an analysis of plasma fibrinogen levels. Systemic LMWH was continued in order to prevent thromboembolism, and fresh frozen plasma was infused daily. Cranial ultrasound was performed daily due to the risk of intracranial haemorrhage. Three days after the patient had been admitted, systemic LMWH was switched to unfractionated heparin (LEO Pharma, Ballerup, Denmark) infusion because the level of anti-FXa was too low. The dose of unfractionated heparin was monitored by activated clotting time targeted at 180–200 s. Local rt-PA treatment was discontinued due to excessive bleeding from the peritoneal dialysis catheter insertion site. Pediatr Nephrol (2009) 24:2069–2071 DOI 10.1007/s00467-009-1172-3

Trombosis venosa renal neonatal: diagnóstico precoz con ecografía Doppler y secuelas a largo plazo

Objective To describe the physiopathological mechanisms in perinatal renal vein thrombosis and the associated risk factors, with emphasis on the clinical and radiological characteristics and on the long-term evolution. Material and methods We retrospectively studied a total of 11 cases of neonatal renal vein thrombosis; the mean age of patients at diagnosis was 3 days. We analyzed the type of presentation, the clinical manifestations, and the findings at B-mode and Doppler ultrasonography, as well as the treatment undertaken and the long-term sequelae. Results At the time of diagnosis, the triad of a palpable mass, unequivocal hematuria, and thrombocytopenia was present in only 63.63% of patients. A prothrombotic risk factor was identified in the newborn or mother in 45.45% of cases. At ultrasonographic examination, all newborns had enlarged kidneys and in all cases it was impossible to differentiate between the renal cortex and the renal medulla. In 4 of the 11 cases, hyperechogenic intramedullary linear images characteristic of the initial stage of thrombosis were identified. Functional follow-up studies using DMSA (dimercaptosuccinic acid) and MAG-3 (mercaptoacetyltriglycine acid) revealed morphological abnormalities in all patients; 7 patients had a nonfunctioning kidney. Conclusions Visualizing echogenic bands within the medulla should alert radiologists to the initial phase of renal vein thrombosis and enable the appropriate treatment to be administered. With the exception of cases discovered before birth, renal vein thrombosis has a poor prognosis, with atrophy and renal failure in the long term.

Neonatal renal vein thrombosis: grey-scale and Doppler ultrasonic features

Renal vein thrombosis RVT is the most common non-catheter related venous thromboembolic events VTE in newborns and is responsible for approximately 10% of all VTE in newborns. Almost 80% of all RVT present within the first month and usually within the first week of life. Currently ultrasound is the radiographic test of choice because of its practicality, sensitivity and lack of adverse effects. The sonographic features vary according to the severity, the extent of the thrombus, the development of collateral circulation and the stage of renal vein thrombosis. Initial diagnostic features include, renal enlargement, echogenic medullary streaks that have a vascular or perivascular distribution, thrombus in the vein prominent echopoor medullary pyramids, subsequently loss of corticomedullary differentiation, reduced echogenicity around the affected pyramids and echogenic band at the extreme apex of the pyramid. Higher resistance index and absent, steady, or less pulsatile venous flow on the affected side compared with flow in the contralateral kidney are helpful Doppler signs. While sonography may be useful in revealing the venous and renal morphology, it is insufficiently reliable for assessment of the functional impact of these morphologic findings. There are no characteristic grey-scale or Doppler ultrasound prognostic features to predict outcome of neonatal RVT and long-term follow up of those children is required.

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

IntroductionRenal vein thrombosis, although rare in adults, is well recognized in neonates and is one of the most common manifestations of neonatal thromboembolic events. The etiology of renal vein thrombosis remains unidentified in the majority of cases. We report a case of renal vein thrombosis in a neonate associated with elevated maternal lipoprotein (a).Case presentationA full-term female infant, appropriate for gestational age, was born via spontaneous vaginal delivery to an 18-year-old primigravida. The infant's birth weight was 3680 g and the Apgar scores were eight and nine at 1 and 5 minutes respectively. Evaluation of the infant in the newborn nursery revealed a palpable mass in the right lumbar area. Tests revealed hematuria and a high serum creatinine level of 1.5 mg/dl. An abdominal ultrasound Doppler flow study demonstrated an enlarged right kidney, right renal vein thrombosis, and progression of the thrombosis to the inferior vena cava. There was no evidence of saggital sinus thrombosis. An extensive work-up of parents for hypercoagulable conditions was remarkable for a higher plasma lipoprotein (a) level of 73 mg/dl and an elevated fibrinogen level of 512 mg/dl in the mother. All paternal levels were normal. The plasma lipoprotein (a) level in the neonate was also normal. The neonate was treated with low molecular weight heparin (enoxaparin) at 1.5 mg/kg/day every 12 hours for 2 months, at which time a follow-up ultrasound Doppler flow study showed resolution of the thrombosis in both the renal vein and the inferior vena cava.ConclusionThere have been no studies to date that have explored the effect of abnormal maternal risk factors on fetal hemostasis. A case-control study is required to investigate whether elevated levels of maternal lipoprotein (a) may be a risk factor for neonatal thrombotic processes. Although infants with this presentation are typically treated with anticoagulation, there is a lack of evidence-based guidelines. Treatment modalities vary between study and treatment centers which warrants the establishment of a national registry.

Neonatal Renal Vein Thrombosis: Review of the English-Language Literature Between 1992 and 2006

Renal vein thrombosis is a complication that occurs in neonates with various underlying risk factors. It carries a grave prognosis for affected kidneys. Anticoagulant and fibrinolytic therapies have been promoted in the past with anecdotal success in some circumstances. However, prospective controlled trials are still lacking, and to date there have been no evidence-based guidelines available for the treatment of neonates with renal vein thrombosis. We retrospectively reviewed all the available medical literature pertaining to renal vein thrombosis published in English during the past 15 years. A total of 271 patients from 13 case series were identified by using the terms "renal vein thrombosis" and "neonates" via PubMed and Cochrane Library searches. Data then were extracted from each of the studies for analysis. During the past 15 years, a male predominance (67.2%) in neonatal renal vein thrombosis has been reported. More than 70% of patients had unilateral renal vein thrombosis, which was more prevalent on the left side (63.6%). The thrombus involved the inferior vena cava and was associated with adrenal hemorrhage in 43.7% and 14.8% of neonates, respectively. Forty percent of the patients were treated conservatively with supportive care alone. Among those patients who received anticoagulation therapy, unfractionated heparin and low molecular weight heparin were used alone in 21.6% and 20.7% of the patients, respectively. Fibrinolytic treatment alone was used in 11.2% of the patients. Only a minority of patients were treated with antithrombin (1.7%), warfarin alone, (0.9%) or underwent surgical intervention (0.3%). The majority (70.6%) of the involved kidneys became atrophic. A total of 9 neonates died with non-renal vein thrombosis-related conditions during the study period. Evidence-based recommendations on treatment cannot be made at the present time. Cooperative prospective studies that involve multiple centers are needed to elucidate the optimal treatment for neonatal renal vein thrombosis.

Bilateral renal vein thrombosis in a twin newborn without known risk factors

Neonatal renal vein thrombosis (RVT) is associated with neonatal stress, catheters and genetic prothrombotic risk factors. In an unusual case of bilateral RVT a twin newborn showed initial good adaptation at birth (weight 2,720 g). The placenta was monochorionic, diamnionic. The infant (gestational week 37) exhibited a severe macrohematuria within 24 hours after birth. Sonography of the kidneys showed a dense cortical parenchyma, loss of cortico-medullary differentiation and negative diastolic flow in both renal arteries and veins, while no thrombus in the main renal veins could be detected. No prothrombotic blood parameters and positive infection serology were detected. Because of acute renal failure peritoneal dialysis was necessary for 6 weeks. The patient was treated by heparinization for 5 days. Interestingly, it was kidney biopsy which confirmed the diagnosis of RVT in addition to the clinical presentation, whereas sonography was unspecific. Histology exhibited the picture of an ischemic contracted kidney with numerous siderophages. At present (age 19 months), the patient suffers from chronic renal failure (calculated glomerular filtration rate according to Schwartz 12 ml/min/1.73 m2). In conclusion, our case teaches that, despite the lack of a clinically obvious shock event, absence of known risk factors and indirect ultrasound findings, renal vein thrombosis should be considered in a macrohematuric newborn with renal failure. For clinical suspicion of RVT correct therapy was initiated, however, the diagnosis remained unclear until a renal biopsy was performed.

Calcified neonatal renal vein and vena caval thrombosis

We present an unusual case of an extensive venous thrombosis (involving the inferior vena cava, bilateral renal veins, gonadal vein and iliac veins) diagnosed in the neonatal period. The CT images revealed the typical diagnostic pattern.