Renal Vein Thrombosis

Imaging of Visceral Vessels

The visceral vasculature is inextricably intertwined with abdominopelvic disease staging, spread, and management in routine and emergent cases. Comprehensive evaluation requires specialized imaging techniques for abnormality detection and characterization. Vascular pathology is often encountered on nondedicated routine imaging examinations, which may obscure, mimic, or confound many vascular diagnoses. This review highlights normal arterial, portal venous, and systemic venous anatomy and clinically relevant variants; diagnostic pitfalls related to image-acquisition technique and disease mimics; and characteristics of common and rare vascular diseases to empower radiologists to confidently interpret the vascular findings and avoid misdiagnosis.

Doppler Ultrasound of the Renal Vasculature

Ultrasound is the first-line imaging modality used in patients with suspected renovascular disease. Common indications include renovascular hypertension and unexplained renal dysfunction. We review the ultrasound imaging findings of various pathologies involving the renal vessels, including the renal arteries (atherosclerotic stenosis, fibromuscular dysplasia, dissection, arteriovenous fistula, and aneurysm) and veins (tumor and bland thrombus as well as vascular compression syndromes). The current role of renal artery stent placement for atherosclerotic stenosis is also discussed.

Endovascular treatment of renal vein thrombosis in a young patient with lung transplant

Spontaneous renal vein thrombosis is a rare entity. A 28-year-old woman with a history of a double-lung transplant was admitted with flank pain and found to have acute kidney injury. A magnetic resonance venogram demonstrated isolated left renal vein thrombosis with extension into the inferior vena cava. Initial management with therapeutic anticoagulation and hydration was unsuccessful. Thus, pharmacochemical thrombectomy was performed. A temporary suprarenal inferior vena cava filter was placed for intraoperative pulmonary prophylaxis. The patient's renal function returned to baseline and remained normal 13 months later. Early incorporation of percutaneous pharmacomechanical thrombectomy can improve renal function when medical therapy alone is unsuccessful.

Epidemiology of antiphospholipid syndrome: macro- and microvascular manifestations

Antiphospholipid syndrome (APS) is a systemic autoimmune disease characterized by thrombotic and non-thrombotic macro- and microvascular manifestations and pregnancy complications in the setting of persistent antiphospholipid antibodies (aPL), namely anticardiolipin antibodies, anti-β2 glycoprotein-I antibodies and lupus anticoagulant. Four decades after its first description, APS prevalence and incidence are still not completely understood due to the limited number of well-designed, population-based multi-ethnic studies. Furthermore, despite decades of efforts to standardise aPL immunoassays, considerable intraassay and interlaboratory variances in aPL measures still exist. Large multicentre APS cohorts have shown a 10-year survival of ∼91% and the presence of catastrophic APS occurs in about 1% of the entire population, associated with a 50% mortality rate. Clinically, any organ can be affected in the context of large, medium or small vessel (artery and/or vein) thrombosis. Macrovascular thrombosis is the hallmark of the disease and veins are more frequently affected than arteries. Deep vein thrombosis/pulmonary embolism thromboembolic disease is the most common APS manifestation, while stroke and transient ischaemic attack are the most frequent arterial thrombosis events. Myocardial infarction can also occur and contributes to increased mortality in APS. A minority of patients present with thrombosis affecting the intraabdominal organs, including the liver, spleen, small and large bowel, and the kidneys. Microvascular thrombosis, including APS nephropathy, chronic skin ulcers and livedoid vasculopathy represent a diagnostic challenge requiring histologic confirmation. In this narrative review we summarize the available evidence on APS epidemiology, focusing on the description of the prevalence of macro- and microvascular manifestations of the disease.

Endovascular Thrombectomy and Lysis for Acute Renal Vein Thrombosis: Indications, Technical Aspects, Outcome, and Disease Etiology

PURPOSE

To report a rare case of acute renal vein thrombosis (RVT) that was treated with endovascular thrombectomy and lysis, and discuss potential etiology and indications for catheter-directed management.

CASE REPORT

A 21-year-old female athlete presented with sudden pain in her left flank and vomiting. A 3-phase computed tomography (CT) angiogram identified total occlusion of the left renal vein with no excretion from the swollen tender left kidney. Catheter-directed thrombolysis and thrombectomy were initiated 24 hours after onset of symptoms. Complete resolution of the RVT with normalized renal function was achieved. Post-operative Doppler ultrasound scan confirmed normal renal resistance and flow in the renal vein. The patient was discharged on Apixaban and remains well at 6 months. Combined hormonal contraception via an intra-vaginal ring and raised Factor VIII activity were the only identified risk factors.

CONCLUSION

Acute complete RVT with impaired kidney function is rare. Combined hormonal contraception and increased Factor VIII activity were potential risk factors. Endovascular thrombectomy and lysis restored renal perfusion and function, and can be used effectively in the management of fit patients with acutely compromised kidney function from total renal vein obstruction.

Intra-abdominal Venous Thromboses and Their Management

While a plethora of articles discuss management of deep venous thromboses in extremities, there is a relative scarcity of literature comprehensively describing intra-abdominal venous thromboses, and their management. Intra-abdominal venous thromboses include iliocaval venous obstruction (ICVO), hepatic venous thrombosis (HVT), portal venous thrombosis (PVT), renal vein thrombosis (RVT), splenic vein thrombosis (SVT), and gonadal vein thrombosis (GVT); each of which provides unique microenvironmental challenges to management. Doppler ultrasound is the first line imaging modality for diagnosis, and computed tomography and magnetic resonance imaging can help define the extent of thrombus burden and aid with interventional planning. Systemic anticoagulation remains the common medical treatment for intra-abdominal venous thrombosis, however, catheter directed thrombolysis and thrombectomy show positive outcomes in ICVO, HVT, PVT, and RVT, with transjugular intrahepatic portosystemic shunt (TIPS) creation especially beneficial in HVT and PVT. In this review article, we describe pathophysiology, clinical features, imaging findings, and current management options for intra-abdominal venous thromboses.

Risk factors of worsening kidney function and mortality in patients with renal vein thrombosis: a retrospective study

BACKGROUND

The outcome of renal vein thrombosis, in particular as for the long-term impact on kidney function, is not fully known. We aimed to study the natural course and outcomes of patients with renal vein thrombosis, in a large, single-center cohort.

METHODS

A single-center retrospective cohort study including patients who were diagnosed with renal vein thrombosis between January 2006 and September 2021 was analyzed. The main outcomes analyzed were worsening kidney function, defined as a decrease in eGFR of at least 40% from baseline, and all-cause mortality.

RESULTS

Eighty-seven patients were included, 56.3% were female, median age was 57 years. Malignancy was the most common cause of renal vein thrombosis (60.9%), followed by post-surgery and trauma (16.1%) and nephrotic syndrome (12.6%). At initial presentation, 65.5% of the patients were asymptomatic; the main signs and symptoms were gross hematuria (20.7%), flank pain (18.4%), and flank tenderness (9.2%). During follow-up, 18 (21.4%) patients experienced worsening kidney function and 57 (65.5%) died. Multivariable analyses showed that the risk of worsening kidney function was higher in patients with nephrotic syndrome (hazard ratio [HR] 18.41; 95% confidence interval [CI], 1.57-216.04), body weight ≥ 60 kg (HR 4.82; 95% CI 1.43-16.32), and malignancy (HR 9.10; 95% CI 1.05-78.63). Symptomatic acute renal vein thrombosis was associated with a lower risk of worsening kidney function compared to asymptomatic or symptomatic chronic renal vein thrombosis (HR 0.12; 95% CI 0.01-0.96). Malignancy (HR 5.45; 95% CI 2.58-11.54), age ≥ 75 years (HR 3.44; 95% CI 1.49-7.93), and serum albumin < 3.0 g/dL (HR 2.88; 95% CI 1.65-5.05) were associated with an increased mortality risk.

CONCLUSION

Renal vein thrombosis is associated with a high rate of worsening kidney function and mortality. It is crucial to promptly identify patients at high risk and initiate early treatment to prevent negative outcomes.

Cancer-Associated Abdominal Vein Thrombosis

Cancer is associated with an increased risk of developing venous thromboembolism, due to its direct influence on the three pillars of Virchow's triad (e.g., compression on the blood vessels by the tumour, blood vessels invasion, and cytokine release), together with the effect of exogenous factors (such as chemotherapy, radiotherapy, surgery). In cancer patients, the risk of thrombosis at unusual sites, such as splanchnic, ovarian and renal vein thrombosis, is also increased. Abdominal vein thromboses are frequently incidental findings on abdominal imaging performed as part of the diagnostic/staging workup or the follow-up care of malignancies. There is little evidence on the management of unusual site venous thromboembolism in cancer patients since there are only a few specific recommendations; thus, the management follows the general principles of the treatment of cancer-associated deep vein thrombosis and pulmonary embolism. This narrative review summarises the latest evidence on cancer-associated abdominal vein thrombosis, i.e., thrombosis of the splanchnic, ovarian and renal veins.

A case of renal vein thrombosis associated with autoimmune hemolytic anemia and eosinophilic granulomatous polyangiitis

Only a few cases of renal vein thrombosis (RVT) occurring in patients with vasculitis have been reported. RVT associated with vasculitis and hemolytic anemia has not been reported yet. We describe here a patient with RVT complicated by pulmonary embolism, autoimmune hemolytic anemia, and eosinophilic granulomatous polyangiitis. A 69-year-old Japanese man who had been treated with corticosteroids was referred to our department for severe proteinuria (4.32 g/gCr). Abdominal ultrasonography showed bilateral RVT, and contrast-enhanced computed tomography showed bilateral pulmonary embolism. Therefore, the patient was diagnosed with RVT complicated by pulmonary embolism. Anticoagulation therapy with heparin followed by apixaban was started. Thereafter, the D-dimer concentration decreased from 8.3 to 1.2 μg/mL, and urinary protein excretion improved to 0.62 g/gCr. Renal function was unchanged with an estimated glomerular filtration rate of 68.8 mL/minute/1.73 m2. The thrombi in both renal veins and pulmonary arteries gradually regressed. Clinicians should be aware of this complication when worsening proteinuria is observed during steroid therapy in patients with autoimmune hemolytic anemia and eosinophilic granulomatous polyangiitis.

Unusual Clinical Presentation of Nephrotic Syndrome With Significant Renal Vein Thrombosis in a Young Male: A Case Report and Literature Review

Primary membranous glomerulopathy is the most common cause of idiopathic nephrotic syndrome, with increasing recognition as an autoimmune-mediated disease. We present the case of a 31-year-old Hispanic male with no prior medical or family history, presenting with one month of dyspnea on exertion, lower extremity, and periorbital edema with a recent diagnosis of pulmonary embolism. Upon further imaging, renal vein thrombosis was discovered with significant lab dysfunction concerning nephrotic syndrome. Further, a workup of kidney biopsy and serum antibody levels revealed the cause to be anti-phospholipase A2 receptor (PLA2R)-mediated.

Comparative outcomes of anticoagulation alone versus anticoagulation plus endovascular intervention in adults with isolated renal vein thrombosis

BACKGROUND

Limited therapeutic strategies are available for adults with isolated renal vein thrombosis (RVT). In the present study, we explore and compare the efficacy of anticoagulation therapy alone vs anticoagulation plus endovascular intervention in the treatment of this rare disease.

METHODS

In the present study, we analyzed the clinical data of RVT patients treated in a tertiary referral center in urban China from April 2012 to April 2022. These patients were classified into anticoagulation therapy (best medical treatment [BMT]) and endovascular intervention (endovascular-based treatment [EBT]) groups. The primary end points, including thrombus clearance and renal function changes, were evaluated by measuring the serum creatinine levels and glomerular filtration rates (GFRs).

RESULTS

A total of 40 consecutive patients with RVT (25 men and 15 women) were included in the present study, with a median age of 37 years (range, 18-72 years). Some patients developed symptoms, including 12 with low back pain (30%), 11 with lower extremity edema (28%), and 10 with abdominal pain (30%). Nephrotic syndrome was the underlying etiology for most patients (30 of 40; 75%). Additionally, 28 patients (70%) developed unilateral RVT, including 18 cases of left RVT (45%). Of the 40 patients, 17 had received BMT (42%) and 23 had received EBT (58%). In the acute phase of RVT, defined as <14 days from symptom onset, the EBT group had higher thrombus clearance and better improvement of creatinine and GFR after treatment compared with the BMT group (P < .05). In the subacute phase, defined as 14 to 30 days after symptom onset, thrombus clearance was higher in the EBT group than in the BMT group (P < .05). However, the improvement in creatinine and GFR were insignificantly different between the two groups (P > .05).

CONCLUSIONS

The etiologies of RVT can and should be investigated. In the present study, RVT was primarily caused by nephrotic syndrome in young patients and also was attributed to malignancy and lupus nephritis. In addition to anticoagulation therapy, endovascular intervention, including catheter-directed thrombolysis and mechanical thrombectomy, contributed to the improvement of renal function in patients with acute RVT. Endovascular intervention markedly promoted thrombus clearance in patients in the subacute phase but did not improve renal function. Therefore, endovascular intervention should be considered if RVT is diagnosed in the acute phase.

Case report: A case of renal arcuate vein thrombosis successfully treated with direct oral anticoagulants

A rare case of a 35 years old woman presented with renal arcuate vein thrombosis (RAVT) and acute kidney injury (AKI) following upper respiratory tract symptoms and toxic substance ingestion. Histopathological evaluation of the patient's kidney tissue indicated a rare venous thrombosis in the renal arcuate veins. Anticoagulation with Apixaban, a direct oral anticoagulant (DOAC), was commenced, and the patient's symptoms resolved during the hospital stay. Hitherto, a limited number of studies have shown the concurrent presentation of RAVT and overt AKI in patients following ingestion of nephrotoxic agents. Further studies are necessary to elucidate the etiology, clinical presentation, and treatment of RAVT. We suggest that Apixaban be studied as a suitable alternative to conventionally used anti-coagulants such as Warfarin in patients who lack access to optimal health care facilities.

Wunderlich Syndrome: Comprehensive Review of Diagnosis and Management

Wunderlich syndrome (WS), which was named after Carl Wunderlich, is a rare clinical syndrome characterized by an acute onset of spontaneous renal hemorrhage into the subcapsular, perirenal, and/or pararenal spaces, without a history of antecedent trauma. Patients may present with a multitude of symptoms ranging from nonspecific flank or abdominal pain to serious manifestations such as hypovolemic shock. The classic symptom complex of flank pain, a flank mass, and hypovolemic shock referred to as the Lenk triad is seen in a small subset of patients. Renal neoplasms such as angiomyolipomas and clear cell renal cell carcinomas that display an increased proclivity for hemorrhage and rupture contribute to approximately 60%-65% of all cases of WS. A plethora of renal vascular diseases (aneurysms or pseudoaneurysms, arteriovenous malformations or fistulae, renal vein thrombosis, and vasculitis syndromes) account for 20%-30% of cases of WS. Rare causes of WS include renal infections, cystic diseases, calculi, kidney failure, and coagulation disorders. Cross-sectional imaging modalities, particularly multiphasic CT or MRI, are integral to the detection, localization, and characterization of the underlying causes and facilitate optimal management. However, large-volume hemorrhage at patient presentation may obscure underlying causes, particularly neoplasms. If the initial CT or MRI examination shows no contributary causes, a dedicated CT or MRI follow-up study may be warranted to establish the cause of WS. Renal arterial embolization is a useful, minimally invasive, therapeutic option in patients who present with acute or life-threatening hemorrhage and can help avoid emergency radical surgery. Accurate diagnosis of the underlying cause of WS is critical for optimal patient treatment in emergency and nonemergency clinical settings. ^©RSNA, 2023 Quiz questions for this article are available through the Online Learning Center.

Acute Renal Vein Thrombosis Following COVID-19 in a Lupus Patient: A Case Report and Review of the Literature

Purpose: The association between COVID-19 and hypercoagulability is well established. This is a case of a patient with systemic lupus erythematosus (SLE) who developed unilateral renal vein thrombosis following COVID-19, the third case described in the international literature so far. Methods: Clinical, laboratory characteristics and outcomes of the patient were described in detail. Literature review was performed on MEDLINE database via Pubmed. Search items included COVID-19, renal infarction, and renal thrombosis. A total of fifty-three cases were located. Of these, only two patients had renal vein thrombosis but none of them carried a diagnosis of SLE. However, six cases have been published so far involving SLE patients in whom thromboembolic events developed following COVID-19, but none of them experienced renal vein thrombosis. Conclusion: The present case adds a new piece to the emerging puzzle of COVID-19 associated hypercoagulability, especially among patients with autoimmune diseases.

Renal Vein Thrombosis Treated With Apixaban in a Patient With COVID-19: A Case Report

Renal vein thrombosis (RVT) is a rare condition characterized by the formation of a blood clot in one or both of the renal veins. Bilateral involvement is more common, but when the condition affects only one side, it usually occurs on the left due to more extensive venous vasculature compared to the right side. RVT can be caused by various factors such as trauma, dehydration, malignancy, and a hypercoagulable state. Acute RVT is typically more severe than chronic, and it can cause symptoms such as renal infarction, acute kidney injury, renal failure, severe flank pain, and hematuria. Some cases of RVT have also been linked to coronavirus disease 2019 (COVID-19), which is widely recognized to induce a hypercoagulable state. The standard treatment for RVT is warfarin but in this case report, we describe a COVID-19 patient with RVT whose thrombus was successfully treated with direct-acting oral anticoagulant (DOAC) apixaban for six months.

A 10-year Australian experience of rare intraabdominal venous thrombosis with comparison to deep vein thrombosis and pulmonary embolism

OBJECTIVE

Intra-abdominal venous thromboembolism is rare with heterogeneous management. We aim to evaluate these thrombosis and compare them to deep vein thrombosis and/or pulmonary embolism.

METHOD

A 10-year retrospective evaluation of consecutive venous thromboembolism presentations (January 2011-December 2020) at Northern Health, Australia, was conducted. A subanalysis of intraabdominal venous thrombosis involving splanchnic, renal and ovarian veins was performed.

RESULTS

There were 3343 episodes including 113 cases of intraabdominal venous thrombosis (3.4%) - 99 splanchnic vein thrombosis, 10 renal vein thrombosis and 4 ovarian vein thrombosis. Of the splanchnic vein thrombosis presentations, 34 patients (35 cases) had known cirrhosis. Patients with cirrhosis were numerically less likely to be anticoagulated compared to noncirrhotic patients (21/35 vs. 47/64, P  = 0.17). Noncirrhotic patients ( n  = 64) were more likely to have malignancy compared to those with deep vein thrombosis and/or pulmonary embolism (24/64 vs. 543/3230, P  < 0.001), including 10 patients diagnosed at time of splanchnic vein thrombosis presentation. Cirrhotic patients reported more recurrent thrombosis/clot progression (6/34) compared to noncirrhotic patients (3/64) (15.6 vs. 2.3 events/100-person-years; hazard ratio 4.7 (95% confidence interval 1.2-18.9), P  = 0.030) and other venous thromboembolism patients (2.6/100-person-years; hazard ratio 4.7, 95% confidence interval 2.1-10.7; P  < 0.001) with comparable major bleeding rates. All renal vein thrombosis were provoked including five malignant-related cases while three ovarian vein thrombosis occurred postpartum. No recurrent thrombotic or bleeding complications were reported in renal vein thrombosis and ovarian vein thrombosis.

CONCLUSION

These rare intraabdominal venous thromboses are often provoked. Splanchnic vein thrombosis (SVT) patients with cirrhosis have a higher rate of thrombotic complications, while SVT without cirrhosis was associated with more malignancy. Given the concurrent comorbidities, careful assessment and individualized anticoagulation decision is needed.

A patient with spontaneous bilateral renal vein thrombosis but no risk factors

INTRODUCTION AND IMPORTANCE

Spontaneous bilateral renal vein thrombosis is a rare condition, especially when the patient has no risk factors.

CASE PRESENTATION

In this report, we describe a patient with bilateral renal vein thrombosis who presented with severe flank pain, renal functions remained normal, and the thrombus resolved completely with anticoagulation. There is no history of hypercoagulable condition in our patient. A one-year followup with CT angiogram revealed that the kidney was functioning normally and that the thrombus in the renal veins had completely resolved.

CLINICAL DISCUSSION

Management of an acute renal vein thrombosis depends upon whether the patient presents with acute kidney injury. In general, patients without acute kidney injury can be treated with therapeutic anticoagulation, whereas those with acute kidney injury should undergo dissolution or removal of the thrombus with thrombolytic therapy with or without thrombectomy.

CONCLUSION

Diagnosis of spontaneous renal vein thrombosis requires a high index of suspicion. Patient can be managed with therapeutic anticoagulation if renal function is intact. If thrombolysis and/or thrombectomy are performed on time, kidney function can be fully restored.

Inferior vena cava and renal vein thrombosis: a rare cause of acute kidney injury in tuberculosis

Recent studies show active tuberculosis induces a prothrombotic state and increases the risk of venous thromboembolism. We report a recently diagnosed case of tuberculosis who presented to our hospital with painful bilateral lower limb swelling and several episodes of vomiting with abdominal pain for 2 weeks. Investigations by a hospital elsewhere 2 weeks ago showed abnormal renal function, misdiagnosed as antitubercular therapy-induced acute kidney injury. D-dimer levels were increased on admission with us, with still deranged renal function. Imaging revealed thrombus at the origin of left renal vein, inferior vena cava and bilateral lower limbs. We started treatment with anticoagulants, which gradually improved kidney function. This case highlights that early diagnosis of renal vein thrombosis and prompt treatment are associated with good clinical outcomes. It also highlights the importance of further studies for risk assessment, prevention strategies and reduction of the burden of venous thromboembolism in patients with tuberculosis.

Albuminuria as a marker of systemic congestion in patients with heart failure

AIMS

Albuminuria is common in patients with heart failure and associated with worse outcomes. The underlying pathophysiological mechanism of albuminuria in heart failure is still incompletely understood. The association of clinical characteristics and biomarker profile with albuminuria in patients with heart failure with both reduced and preserved ejection fractions were evaluated.

METHODS AND RESULTS

Two thousand three hundred and fifteen patients included in the index cohort of BIOSTAT-CHF were evaluated and findings were validated in the independent BIOSTAT-CHF validation cohort (1431 patients). Micro-albuminuria and macro-albuminuria were defined as urinary albumincreatinine ratio (UACR) 30 mg/gCr and 300 mg/gCr in spot urines, respectively. The prevalence of micro- and macro-albuminuria was 35.4 and 10.0, respectively. Patients with albuminuria had more severe heart failure, as indicated by inclusion during admission, higher New York Heart Association functional class, more clinical signs and symptoms of congestion, and higher concentrations of biomarkers related to congestion, such as biologically active adrenomedullin, cancer antigen 125, and N-terminal pro-B-type natriuretic peptide (NT-proBNP) (all P 0.001). The presence of albuminuria was associated with increased risk of mortality and heart failure (re)hospitalization in both cohorts. The strongest independent association with log UACR was found for log NT-proBNP (standardized regression coefficient 0.438, 95 confidence interval 0.350.53, P 0.001). Hierarchical clustering analysis demonstrated that UACR clusters with markers of congestion and less with indices of renal function. The validation cohort yielded similar findings.

CONCLUSION

In patients with new-onset or worsening heart failure, albuminuria is consistently associated with clinical, echocardiographic, and circulating biomarkers of congestion.

Trauma-associated left renal vein thrombosis with nutcracker syndrome

Background

Nutcracker syndrome is a compression of the left renal vein between the superior mesenteric artery and aorta, resulting in thrombogenesis. While renal vein thrombosis caused by renal disease is more common, solitary left renal vein thrombosis with nutcracker syndrome is rare.

Case Presentation

We present the case of a patient with trauma-associated left renal vein thrombosis with nutcracker syndrome. A 24-year-old woman with low body mass index taking oral contraceptives was admitted for trauma. She had multiple injuries, including thoracolumbar fractures, for which elective spinal fusion surgery was scheduled. As the D-dimer level elevated to 82.5 μg/dL preoperatively, enhanced computed tomography was performed, which revealed a solitary left renal vein thrombus.

Conclusion

This is the report of solitary left renal vein thrombosis in a patient with nutcracker syndrome after trauma. Patients with low body mass index and coagulopathy might have solitary left renal vein thrombosis associated with nutcracker syndrome.

Renal arcuate vein thrombosis-induced acute kidney injury: a rare multiple-Hit-mediated disease

Background

Renal arcuate vein thrombosis (RAVT) is a rare and recently recognized cause of acute kidney injury (AKI) in young adults. However, the precise incidence and underlying pathophysiologic mechanisms leading to AKI in these patients remain elusive.

Methods

This study included all patients who underwent a kidney biopsy over a 40-month period sent to the pathology department of Necker-Enfants Malades Hospital, with evidence of RAVT. We performed coagulation tests, genetic testing for thrombophilia, complete urine toxicologic screening and kidney metagenomic sequencing to identify an underlying cause of thrombosis.

Results

We report five pediatric cases of RAVT discovered on kidney biopsy performed in the setting of unexplained AKI. Investigations did not reveal an underlying cause of thrombosis but only a significant nonsteroidal anti-inflammatory drugs (NSAIDs) use was reported in 4/5 patients, supporting a potential link between NSAIDs use and RAVT. By performing metagenomic sequencing on kidney biopsy samples, we detected severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in the kidney of one patient. These results suggest that systemic SARS-CoV-2 infection may also be a key contributing factor of renal thrombosis, particularly by inducing potential endothelial disruption.

Conclusions

In conclusion, RAVT-induced AKI appears to be a multiple hit-mediated disease in which NSAIDs consumption and viral infection such as SARS-CoV-2 may be crucial contributing factors. These findings may have significant public health implications given the prevalence of NSAIDs use in the general population. Increased awareness and additional study of future cases may lead to a better understanding of this rare cause of AKI in children and young adults.

A Case of Renal Vein Thrombosis Associated With COVID-19 Treated With Rivaroxaban

Renal vein thrombosis (RVT) is a rare form of deep venous thrombosis. It usually involves one or both renal veins and one of their branches. Most cases were reported in patients with nephrotic syndrome or inherited hypercoagulability syndromes. RVT can present with flank pain, hematuria, and acute kidney injury but can also present asymptomatically and be incidentally discovered on abdominal or renal imaging. The management of RVT is usually with warfarin for at least six to 12 months and periodically is continued if the patient is in the nephrotic range. Direct-acting oral anticoagulants (DOACs) have not been well studied in cases of RVT, especially in patients with coronavirus disease 2019 (COVID-19). We present a case of RVT in the setting of COVID-19 that was treated successfully with a DOAC, rivaroxaban, with complete resolution of the thrombus.

Acute kidney injury in pediatrics: an overview focusing on pathophysiology

Acute kidney injury (AKI) is defined as an abrupt decline in glomerular filtration rate, with increased serum creatinine and nitrogenous waste products due to several possible etiologies. Incidence in the pediatric population is estimated to be 3.9 per 1,000 hospitalizations, and prevalence among children admitted to intensive care units is 26.9%. Despite being a condition with important incidence and morbimortality, further evidence on pathophysiology and management among the pediatric population is still lacking. This narrative review aimed to summarize and discuss current data on AKI pathophysiology in the pediatric population, considering all the physiological particularities of this age range and common etiologies. Additionally, we reported current diagnostic tools, novel biomarkers, and newly proposed medications that have been studied with the aim of early diagnosis and appropriate treatment of AKI in the future.

Treatment of Atypical Clots

The term unusual site thrombosis refers to the occurrence of venous thromboembolism outside of the lower limbs and the pulmonary arteries. Unusual site thrombosis can virtually affect any venous segment, with the most common and/or clinically relevant sites including the upper limbs veins, the retinal veins, the splanchnic veins and the cerebral veins. Clinical features are obviously heterogeneous, while many predisposing factors are common, though with different prevalence among the various disorders. Antithrombotic therapy is prescribed to most patients, but the type, intensity, and duration of treatment vary both within and among patient groups. Increasing evidence is supporting the use of the direct oral anticoagulants in patients with upper limb deep vein thrombosis, cerebral vein thrombosis, and with splanchnic vein thrombosis. This article will review available evidence on the treatment of venous thrombosis occurring in unusual sites.

Renal Vein Thrombosis on Point-of-care Ultrasound in the Emergency Department: A Case Report

Introduction

This case report of renal vein thrombosis found on emergency bedside ultrasound illustrates the expanding role of point-of-care ultrasound (POCUS) in rapidly identifying rare renal pathologies.

Case Report

A 16-year-old female with a complex medical history presenting with right-sided abdominal pain and tenderness was found to have significant renal POCUS findings consistent with renal vein thrombosis.

Conclusion

In the medically complex patient with nonspecific chief complaints, it can be challenging to rapidly narrow a broad differential diagnosis. Point-of-care ultrasound has proven to be an extremely useful tool for this purpose. As emergency physicians become more proficient in the use of ultrasonography, it is likely that POCUS will be used with increasing frequency to identify additional pathology outside its traditional applications.

Nutcracker syndrome as the main cause of left renal vein thrombus and pulmonary thromboembolism

INTRODUCTION

Left renal vein thrombus complicating nutcracker syndrome is relatively rare. To the best of our knowledge, there have been only four previous case reports. Furthermore, there have been no reports of pulmonary thromboembolism caused by nutcracker syndrome. Herein, we report a rare case of pulmonary thromboembolism caused by nutcracker syndrome and its clinical management.

CASE PRESENTATION

A 40-year-old man was admitted to our hospital with acute left flank pain. Computed tomography angiography revealed compression of the left renal vein between the aorta and the superior mesenteric artery with a left renal vein thrombus. Furthermore, computed tomography revealed bilateral pulmonary thromboembolism. Rivaroxaban was administered as an anticoagulant. Twenty days after initiation, computed tomography revealed complete resolution of pulmonary thromboembolism and left renal vein thrombus, and repeated computed tomography showed no recurrence.

CONCLUSION

This case report highlights nutcracker syndrome as a likely cause of pulmonary thromboembolism.

CT findings after left renal vein division during abdominal aortic surgery

BACKGROUND

The rationale behind left renal vein division (LRVD) is the assumption that adequate collateral draining channels will develop.

PURPOSE

To describe computed tomography (CT) findings after LRVD during aortic surgery.

MATERIAL AND METHODS

Among 61 consecutive patients who underwent LRVD during aneurysm repair or revascularization for aortic occlusive disease between January 2003 and December 2017, 51 patients (40 men, mean age 71.4 ± 8.4 years) were enrolled. Contrast-enhanced CT images were analyzed to evaluate collateral drainage, patency, left renal vein diameter, and left renal parenchymal thickness. A total of 115 radiologic reports were reviewed to check whether these findings were accurately mentioned.

RESULTS

The median time period of the first postoperative follow-up CT was 36 days (range 7-1351 days). The gonadal vein (n = 47) was the most common collateral draining channel, followed by the retroperitoneal veins (n = 42) and adrenal vein (n = 33). Thrombosis occurred in five patients between postoperative days 7 and 17 in the remnant renal vein (n = 3), remnant renal vein plus gonadal and adrenal veins (n = 1), and gonadal vein (n = 1). There was a significant decrease in renal vein diameter (-0.48 ± 2.12 mm, P = 0.006). There was no significant difference in parenchymal thickness (-0.25 ± 1.27 mm, P = 0.193). Neither LRVD nor any associated findings were correctly stated on radiologic reports.

CONCLUSION

Postoperative contrast-enhanced CT can delineate collateral draining channels and complications following LRVD. However, these findings tend to be either missed or misinterpreted.

Acute Kidney Injury in Monoclonal Gammopathies

Monoclonal gammopathies (MG) encompass a variety of disorders related to clonal expansion and/or malignant transformation of B lymphocytes. Deposition of free immunoglobulin (Ig) components (light or heavy chains, LC/HC) within the kidney during MG may result over time in multiple types and degrees of injury, including acute kidney injury (AKI). AKI is generally a consequence of tubular obstruction by luminal aggregates of LC, a pattern known as “cast nephropathy”. Monoclonal Ig LC can also be found as intracellular crystals in glomerular podocytes or proximal tubular cells. Proliferative glomerulonephritis with monoclonal Ig deposits is another, less frequent form of kidney injury with a sizable impact on renal function. Hypercalcemia (in turn related to bone reabsorption triggered by proliferating plasmacytoid B cells) may lead to AKI via functional mechanisms. Pharmacologic treatment of MG may also result in additional renal injury due to local toxicity or the tumor lysis syndrome. The present review focuses on AKI complicating MG, evaluating predictors, risk factors, mechanisms of damage, prognosis, and options for treatment.

Direct oral anticoagulants for unusual-site venous thromboembolism

Direct oral anticoagulants (DOACs) are currently the preferred oral anticoagulant treatment for most of the patients with deep vein thrombosis of the lower extremities and/or pulmonary embolism. DOACs have several advantages over vitamin K antagonists, such as availability of fixed dosages, fewer drug interactions, faster onset of action, shorter half-life, and lower risk of major and intracranial bleeding. Although the evidence on the use of DOACs in patients with unusual-site venous thromboembolism (VTE) is limited to a few, small randomized controlled trials, these drugs are increasingly used in clinical practice, and several observational cohort studies have been published recently. This narrative review will describe the latest evidence for the use of the DOACs in patients with thrombosis in atypical locations (splanchnic, cerebral, upper extremity, ovarian, and renal vein thrombosis) and will provide some practical advice for their use in patients with unusual-site VTE.

Catheter Directed Thrombectomy Under Temporary Catheter Based Filter Protection in Renal Vein Thrombosis and Contraindication to Anticoagulation

INTRODUCTION

A 55 year old man who suffered from recurrent traumatic multi-organ bleeding presented with deterioration in kidney function and pulmonary embolism caused by a newly diagnosed renal vein thrombosis during hospitalisation.

REPORT

Complete clot removal was performed successfully by catheter directed aspiration. Thrombotic emboli were captured in a temporary filter device. A post-interventional computed tomography scan showed full restoration of the occluded renal vein.

DISCUSSION

Use of a temporary catheter based vena cava filter (Capturex) during catheter directed thrombectomy is safe and should be considered to prevent thrombo-embolism in selected cases when any rheolytic therapy is contraindicated.

"Renal emergencies: a comprehensive pictorial review with MR imaging"

Superior soft-tissue contrast and high sensitivity of magnetic resonance imaging (MRI) for detecting and characterizing disease may provide an expanded role in acute abdominal and pelvic imaging. Although MRI has traditionally not been exploited in acute care settings, commonly used in biliary obstruction and during pregnancy, there are several conditions in which MRI can go above and beyond other modalities in diagnosis, characterization, and providing functional and prognostic information. In this manuscript, we highlight how MRI can help in further assessment and characterization of acute renal emergencies. Currently, renal emergencies are predominantly evaluated with ultrasound (US) or computed tomography (CT) scanning. US may be limited by various patient factors and technologist experience while CT imaging with intravenous contrast administration can further compromise renal function. With the advent of rapid, robust non-contrast MRI, and magnetic resonance angiography (MRA) imaging studies with short scan times, free-breathing techniques, and lack of ionization radiation, the utility of MRI for renal evaluation might be superior to CT not only in diagnosing an emergent renal process but also by providing functional and prognostic information. This review outlines the clinical manifestations and the key imaging findings for acute renal processes including acute renal infarction, hemorrhage, and renal obstruction, among other entities, to highlight the added value of MRI in evaluating the finer nuances in acute renal emergencies.

Acute bilateral renal vein thrombosis diagnosis and management: a case report

Undifferentiated abdominal pain accounts for a significant proportion of emergency presentations and often presents as a diagnostic dilemma. Renal vein thrombosis (RVT) has many aetiologies including nephrotic syndrome, malignancy, trauma, infection and hypercoagulable states. RVT should be considered in cases of persistent abdominal pain where other, more common, pathologies have been excluded. We present the case of a 42-year-old male with a delayed diagnosis of bilateral RVT after presenting with multiple episodes of intractable abdominal pain and adverse sequelae of this condition. This case report aims to emphasize the importance of prompt RVT recognition and the utility of bedside emergency department (ED) investigations, which can guide initial differential diagnoses of abdominal pain, reduce the delay in diagnosis as well as limit unnecessary investigations.

Localized solitary left renal vein thrombus complicating nutcracker syndrome: a case report and review of the literature

Nutcracker syndrome (NCS) refers to compression of the left renal vein (LRV) between the abdominal aorta and the superior mesenteric artery (SMA). The clinical presentation of NCS includes hematuria, abdominal and left flank pain, gonadal varices, and varicocele formation. Theoretically, thrombosis can occur in the LRV in patients with NCS. However, an isolated solitary left renal vein thrombus (LRVT) complicating NCS is rare. In addition, the clinical features of an LRVT complicating NCS remain unclear. We describe a 43-year-old woman presenting with an asymptomatic LRVT complicating NCS. She was referred to our hospital for investigation of dysfunctional uterine bleeding, and detailed examination revealed endometrial cancer. Computed tomography angiography (CTA) and Doppler ultrasonography revealed compression of the LRV between the aorta and the SMA, as well as an LRVT. CTA performed 4 months after the administration of an anticoagulant showed complete disappearance of the LRVT. We have also included a review of published reports describing LRVT complicating NCS and discussed the clinical features of such a presentation.

Isolated renal vein and inferior vena cava thrombus following blunt trauma abdomen. A rare case scenario

Objective

Renal vein thrombosis in adults occurs as a result of various etiologies such as nephrotic syndrome, renal cell cancer, hypercoagulable state and trauma. Renovascular injury happens in 3% to 4% of patients with blunt abdominal trauma and usually occurs in association with significant injury to the abdominal viscera or skeleton.

Method

A 40-year-old female suffered from blunt abdominal trauma following a road traffic accident while she was travelling as a pillion rider on a two-wheeler vehicle.

Result

The patient was diagnosed with left renal vein and inferior vena cava thrombus without any associated renal parenchymal or injuries to other organs. She was managed conservatively with anticoagulants and regular monitoring. Follow up imaging after 3 months showed complete resolution of thrombus.

Conclusion

Traumatic renal vein or inferior vena cava injury usually occurs in combination with renal arterial or parenchymal injury. Isolated major venous injury is rare.

A Case of Isolated Unilateral Right Renal Vein Thrombosis Associated with Bilateral Pulmonary Embolism Treated with Rivaroxaban a Direct-Acting Oral Anticoagulant

Patient: Female, 44

Final Diagnosis: Renal vein thrombosis

Symptoms: Dyspnea

Medication: —

Clinical Procedure: —

Specialty: Cardiology

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

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

The forgotten urinalysis: an integral part of unmasking thrombophilia

A 43-year-old female presented with flank pain of two days duration. She had been admitted previously for bilateral lower extremity edema which had not improved with diuresis. Abdominal Imaging showed left ovarian vein thrombosis and left renal vein thrombosis extending into the IVC. Chest imaging revealed right lower lobe segmental pulmonary emboli. Careful review of serial urinalysis during previous admissions revealed significant proteinuria. Confirmatory urine tests followed by a renal biopsy led to a diagnosis of membranous nephropathy. We report a case of acute diffuse thromboembolism due to membranous nephropathy, unmasked by serial abnormal urinalysis.

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.

Management of Hematuria in Children

Purpose of Review

This paper provides a review of the diagnostic evaluation of both microscopic and gross hematuria, as well as an update on the pathogenesis, clinical features, and treatment strategies for several diseases of the kidneys and urinary tract in which hematuria is a prominent finding. The goal is to provide pediatric providers with a framework through which appropriate and expeditious referral to subspecialty care may be made for definitive treatment.

Recent Findings

Although there has been great heterogeneity in published treatment strategies for many causes of hematuria, the Kidney Diseases Improving Global Outcomes (KDIGO) initiative has recently set forth guidelines for glomerular diseases in particular to provide evidence-based strategies for treatment. In addition, recent advances in the understanding of molecular pathogenesis and long-term clinical outcomes for other non-glomerular diseases has led to updates in treatment strategies summarized in this review.

Summary

As the pediatric primary care provider is often the first point of contact for children with microscopic or gross hematuria, updated knowledge as to the epidemiology and management of several of the various causes of hematuria will improve the care of children by both avoiding extraneous testing and interventions and implementing definitive care (either by expectant management and reassurance or by subspecialty referral) in a timely manner.

Pathological assessment of allograft nephrectomy: An Iranian experience

BACKGROUND

The aim of this study was to determine the pathologic causes of renal allograft failure in transplant nephrectomy specimens.

MATERIALS AND METHODS

In this cross-sectional study performed in the referral transplant center of Isfahan, Iran, medical files of all patients who underwent nephrectomy in 2008-2013 were studied. Age at transplantation, sex, donor's characteristics, causes of primary renal failure, duration of allograft function, and pathologic reasons of nephrectomy were extracted. Slides of nephrectomy biopsies were evaluated. Data were analyzed using SPSS.

RESULTS

Medical files of 39 individuals (male: 56.4%; mean age: 35.1 ± 16.0 years) were evaluated. The main disease of patients was hypertension (17.9%), and most cases (64.1%) were nephrectomized < 6 months posttransplantation. Renal vein thrombosis (RVT) (51.3%) and T-cell-mediated rejection (TCMR) (41.0%) were the most prevalent causes of transplanted nephrectomy. Cause of primary renal failure was correlated to nephrectomy result (P = 0.04). TCMR was the only pathologic finding in all of patients nephrectomized >2 years posttransplantation. There were 14 cases in which biopsy results showed a relationship between primary disease of patients and pathologic assessment of allograft (P = 0.04). A significant relationship between transplantation-nephrectomy interval and both the nephrectomy result and histopathologic result existed (P < 0.0001). A relationship between primary allograft biopsy appearance and further assessment of nephrectomized specimen (P < 0.001) existed as well.

CONCLUSION

The most pathologic diagnoses of nephrectomy in a period of less than and more than 6 months posttransplantation were RVT and TCMR, respectively. Early obtained allograft protocol biopsy is suggested, which leads to better diagnosis of allograft failure.

Color Doppler ultrasound diagnosis of intrarenal vein thrombosis: A rare case report and literature review

RATIONALE

We present a case of intrarenal vein thrombosis (IRVT) diagnosed by ultrasound (US). To the best of our knowledge, this is the first reported case in the imaging literature.

PATIENT CONCERNS

A 15-year-old boy with a 4-year history of thrombocytopenic purpura presented to the emergency room with a 2-day history of sudden-onset severe left flank pain associated with gross hematuria.

DIAGNOSES

Hypercholesterolemia, proteinuria, and elevated plasma creatinine level were present. The US examination showed obscurely structured, sparsely distributed arterial and venous flow signals, and an increased resistance index (RI) in a localized area. The diagnosis was acute renal failure and nephrotic syndrome accompanied by left IRVT.

INTERVENTIONS

The patient was treated with anticoagulation therapy for 1 month.

OUTCOMES

Clinical symptoms were relieved. The US re-examination revealed that the arterial flow spectra had returned to normal. Also, more venous flow signals were observed in the involved area, suggesting thrombolysis.

LESSONS

This previously unreported case should alert sonographers to include IRVT in the differential diagnosis of flank pain associated with hematuria. In such cases, both kidneys and different areas of the same kidney should be scanned and compared. Some features, including an obscure structure and an increased RI for the involved area indicate possible IRVT.

Adult Idiopathic Renal Vein Thrombosis Mimicking Acute Pyelonephritis

Renal Vein Thrombosis (RVT) is a rarely encountered condition. It occurs due to a hypercoagulable state in the body, caused by nephrotic syndrome and membranous nephropathy in the adults. Mode of presentation is variable. In chronic form, it may remain silent for a long time and presenting later with symptoms of pedal oedema, varicocele, proteinuria. In acute state, it manifests as flank pain, nausea or haematuria. We present a case of 25-year-old male, with left sided flank pain, haematuria and nausea for 4 days. Ultrasound showed enlarged kidney with altered echogenecity. No calculus was found on x-ray. Empirical antibiotics were started considering possibility of Acute Pyelonephritis (APN). With no improvement seen after 3 days along with no growth on urine culture, CT-urography was done. It revealed enlarged non-excreting left kidney with thrombus seen over left renal vein extending into Inferior Vena Cava (IVC). Immediate anticoagulant therapy was started. Patients recovered gradually and after 6 months, follow-up CT showed disappearance of thrombosis. Anticoagulants were withdrawn gradually. So we highlight the possibility of RVT as a differential diagnosis to APN or renal colic and its evaluation and management.

Characteristics of patients diagnosed with renal vein thrombosis and glomerulopathy: a case series

BACKGROUND

Few contemporary studies have evaluated the clinical characteristics of patients with biopsy-proven glomerulopathy diagnosed with renal vein thrombosis (RVT).

METHODS

Retrospective case series study within an integrated health system in a 12-year period (January 1, 2000 through December 31, 2011) investigating clinical characteristics of all adult patients who underwent native or transplant kidney biopsy and also had a diagnosis of RVT. Patient characteristics, diagnostic studies, and outcomes were evaluated.

RESULTS

Among 3763 eligible patients, 17 had imaging confirmed RVT. Of these, 15 had membranous nephropathy (idiopathic or secondary to autoimmune disease). Although the biopsy population included primary and secondary glomerular disease patients, all 17 RVT patients had severe nephrotic syndrome and profound hypoalbuminemia with mean (SD) of albumin: 1.5 g/dL (0.66).

CONCLUSION

Clinically significant RVT in patients with glomerulopathy appears to be a rather rare entity, occurring predominantly in patients with severe nephrotic syndrome due to idiopathic membranous nephropathy and membranous nephropathy secondary to autoimmune disease.