Renal arteriovenous malformation: sonographic findings

Congenital Renal Arteriovenous Malformation: Diagnostic Clues and Methods

Background and objectives: Renal arteriovenous malformation (AVM) is a rare disease and is difficult to be diagnosed by conventional methods because of its rarity. In this study, we investigated the diagnostic clues, and made an algorithm for the better diagnosis of renal AVM. Materials and Methods: We reviewed 13 patients who were diagnosed with AVM by using renal angiography from 1986 to 2020 at our institutes. We evaluated clinical features, diagnostic tools, treatment modalities, and outcomes after the treatment of patients. Results: All patients were female, and the mean age was 36.9 years (range 19 to 54 years). Twelve (92.3%) patients complained of gross hematuria. Four (30.8%) patients showed symptoms in relation with pregnancy and delivery. Angiographic findings demonstrated cirsoid type in 10 patients and aneurysmal type in 3 patients. Among the 11 patients who underwent computed tomography, AVMs were detected in 3 (27.3%) patients. Renal duplex Doppler was performed in 6 patients, and all of these patients were diagnosed with AVM, demonstrating a vascular turbulence or blood-rich area. Twelve patients were initially treated with transarterial embolization. Nephrectomy was performed in two patients due to persistent bleeding with hypovolemic shock. Conclusions: We should consider possible AVMs in patients who were not detected by conventional work up for hematuria, especially in mid-aged, pregnant, or recently delivered women. Renal duplex Doppler might be the optimal diagnostic modality in these patients. Our diagnostic algorithm could be aid to diagnosis and treatment for renal AVM patients.

A Case of Arteriovenous Fistula After Kidney Trauma Mimicking Tumor

Renal arteriovenous fistulas are rare complications of kidney injury that are usually caused by penetrating or blunt abdominal trauma, percutaneous or open biopsy, or surgery. We report a case of renal arteriovenous fistula after blunt abdominal trauma of a male patient who had traffic accidents. Computed tomography images show arteriovenous fistula lesion mimicking the tumor of the renal pelvis. Through this case, we present how to identify and avoid being confused in diagnosis as well as introduce its clinical manifestations, imaging, and treatment.

Renal arteriovenous malformation mimicking hydronephrosis-hidden danger

Renal arteriovenous malformations (AVMs) are rare, with an incidence of approximately 0.04%. Diagnosis is often challenging due to mimics of AVMs. We report a case of renal AVM mimicking hydronephrosis on ultrasound and unenhanced computed tomography (CT). A 24-year-old female with background of recurrent urinary tract infections (UTIs) presented to the Accident and Emergency department with 1 day history of bilateral flank pain, dysuria, rigors and pyrexia. Urine dipstick showed microscopic haematuria and blood tests showed mild neutrophilia. Dilated right renal pelvis was seen on ultrasound. Unenhanced CT of the urinary tract demonstrated right hydronephrosis with no evidence of calculi. Subsequent Uro-radiology meeting discussion concluded that renal pelvis might be pus-filled and recommended an urgent nephrostomy. However, ultrasound Doppler scan performed at the time of the planned nephrostomy demonstrated colour flow within dilated renal pelvis suggestive of an AVM. Nephrostomy was abandoned and subsequent CT angiogram confirmed a large congenital AVM. The patient was referred for embolization.Colour flow ultrasound imaging is a simple and quick technique to diagnose AVMs. However, as in our case, when colour flow Doppler imaging was not used at the initial ultrasound, the opportunity to obtain an accurate diagnosis was missed. If the subsequently planned nephrostomy had taken place, this may have led to potentially serious outcomes. We suggest that colour flow imaging should be used prior to nephrostomy insertion to differentiate hydronephrosis from vascular abnormalities.

A Renal Arteriovenous Malformation Case Study: The Importance of Utilizing Color Doppler During Point-of-Care Sonography

We report the successful diagnostic and observational treatment of a renal arteriovenous malformation (RAVM) diagnosed with point-of-care color Doppler imaging. The patient presented with clinical symptoms suggestive of hydronephrosis. A physician-performed point-of-care sonography demonstrated gray-scale imaging that initially appeared to confirm renal pelvis dilatation. However, the addition of color Doppler revealed color blooming resembling a vascular turbulence within the kidney and the renal pelvis. A computed tomography angiogram was used to confirm the diagnosis of RAVM as the etiology of renal pelvic dilation. This case highlights the potential value of using color Doppler as a standard component for physicians who evaluate patients believed to have hydronephrosis.

Renal Arteriovenous Shunts: Clinical Features, Imaging Appearance, and Transcatheter Embolization Based on Angioarchitecture

Renal arteriovenous (AV) shunt, a rare pathologic condition, is divided into two categories, traumatic and nontraumatic, and can cause massive hematuria, retroperitoneal hemorrhage, pain, and high-output heart failure. Although transcatheter embolization is a less-invasive and effective treatment option, it has a potential risk of complications, including renal infarction and pulmonary embolism, and a potential risk of recanalization. The successful embolization of renal AV shunt requires a complete occlusion of the shunted vessel while preventing the migration of embolic materials and preserving normal renal arterial branches, which depends on the selection of adequate techniques and embolic materials for individual cases, based on the etiology and imaging angioarchitecture of the renal AV shunts. A classification of AV malformations in the extremities and body trunk could precisely correspond with the angioarchitecture of the nontraumatic renal AV shunts. The selection of techniques and choice of adequate embolic materials such as coils, vascular plugs, and liquid materials are determined on the basis of cause (eg, traumatic vs nontraumatic), the classification, and some other aspects of the angioarchitecture of renal AV shunts, including the flow and size of the fistulas, multiplicity of the feeders, and endovascular accessibility to the target lesions. Computed tomographic angiography and selective digital subtraction angiography can provide precise information about the angioarchitecture of renal AV shunts before treatment. Color Doppler ultrasonography and time-resolved three-dimensional contrast-enhanced magnetic resonance angiography represent useful tools for screening and follow-up examinations of renal AV shunts after embolization. In this article, the classifications, imaging features, and an endovascular treatment strategy based on the angioarchitecture of renal AV shunts are described.

Finite element analysis of uncommonly large renal arteriovenous malformation--adjacent renal cyst complex

BACKGROUND

Renal arteriovenous malformation (RAVM) represents abnormal communication between the intrarenal arterial and venous system. The purpose of this study was to investigate hemodynamics and biomechanics quantities which may influence the instability of RAVM and imply clinical complications.

METHODS

A detailed 3D reconstruction of RAVM was obtained from the patient CT scans, aortic inlet flow was measured by color-flow Doppler ultrasound, while material characteristics were adopted from the literature. A numerical finite element analysis (FEA) of the blood flow was performed by solving the governing equations for the viscous incompressible flow. The physical quantities calculated at the systolic and diastolic peak moment were velocity, pressure, shear stress and drag forces.

RESULTS

We reported a case of a 50-year-old patient with a large RAVM and adjacent renal cyst, who unsuccessfully underwent two attempts of embolization that resulted in the consequent nephrectomy. FEA showed that the cyst had a very low pressure intensity and velocity field (with unstable flow in diastolic peak). For both systolic and diastolic moments, increased values of wall shear stress were found on the places with intensive wall calcification. Unusually high values of drag force which would likely explain the presence of pressure in the cystic formation were found on the infero-medial side where the cyst wall was the thinnest and where the flow streamlines converged.

CONCLUSIONS

FEA showed that the hemodynamics of the cyst-RAVM complex was unstable making it prone to rupture. Clinically established diagnosis of imminent rupture together with unfavorable hemodynamics of the lesion consequently made additional attempts of embolization risky and unsuccessful leading to total nephrectomy.

Ruptured renal arteriovenous malformation successfully treated by catheter embolization: a case report

BACKGROUND

Renal arteriovenous fistula (RAVF) is a comparatively rare malformation. Here, we report a case of ruptured RAVF that was successfully treated by catheter embolization.

CASE PRESENTATION

An 89-year-old female was transferred to our institution with massive gross hematuria in March 2011. Plain abdominal computed tomography (CT) revealed dilated left renal pelvis with high-density contents. Hematoma was suspected. Subsequent plain abdominal magnetic resonance imaging revealed left hydronephrosis and blood retention in the dilated left renal pelvis. No renal or ureteral cancer was evident. Hematuria was conservatively treated using hemostatic agents but hematuria persisted. Repeated urinary cytology revealed no malignant cells. On day 9, the patient went into septic and/or hemorrhagic shock. Fluid and catecholamine infusion, blood transfusion, and antibacterial drugs were rapidly initiated, and the patient's general condition gradually improved. Contrast-enhanced abdominal CT revealed marked expansion of the hematoma in the renal pelvis and microaneurysms in the segmental arteries of the left kidney. Inflammation improved, and a left double-J stent was inserted. Selective renal angiography revealed RAVF with microaneurysms in the left segmental arteries; therefore, catheter embolization using metallic coils was performed, which resolved hematuria.

CONCLUSION

We report a case of ruptured renal arteriovenous malformation, which was successfully treated by catheter embolization.

Congestive hepatopathy secondary to large renal arteriovenous malformation

A 75-year-old woman presented with acute onset dyspnoea, and was found to have signs of pulmonary congestion on clinical examination. Imaging revealed cardiomegaly and coincident congestive hepatopathy, secondary to a left renal arteriovenous malformation. The presence of a high flow vascular shunt in the left kidney was possibly the causative factor behind both the high-output cardiac failure and congestive hepatopathy.

[Renal arteriovenous fistula]

Arteriovenous malformations are important but uncommon differential diagnoses for space occupying renal lesions with unknown genesis. In the following case report, a 41-year-old patient complained about continuing right flank pain. Computer tomography indicated a possible renal cell carcinoma and the patient was admitted to our clinic. Further diagnostics, including contrast medium-enhanced bolus CT, colour coded duplex sonography, renovasography and MR-angiography, revealed a large arteriovenous fistula of the entire right kidney. Because of the size and aneurysmatic appearance of this fistula, we performed a nephrectomy. Since this operation the patient has been free of complaints.

Radiofrequency ablation of a recanalized renal arteriovenous malformation

Radiofrequency (RF) ablation is becoming established as a method of treatment of small renal neoplasms. Successful RF ablation of a renal arteriovenous malformation (AVM) was performed in a patient who had previously undergone coil embolization and experienced hematuria after the feeding vessels recanalized. The 3.5-cm lesion was successfully treated with RF ablation, resulting in cessation of hematuria. At follow-up, there was no residual enhancement of the AVM on computed tomography and the lesion had decreased in size.

Congenital bilateral renal arteriovenous malformation: an unrecognized cause of renal failure

Congenital renal arteriovenous malformations (AVM) are very rare abnormal communications between arteries and veins. These lesions are almost always unilateral, predominantly in the right kidney, and usually asymptomatic until adulthood. We present a unique case of bilateral renal AVM in a 10-year-old white boy who developed renal failure requiring renal transplantation. Microscopic sections of an atrophic right and a slightly larger left kidney with tortuous and dilated hilar vessels showed elaborate derangement of arteries and veins insinuating between lobules. Glomeruli were diffusely enlarged with increased number of capillary loops. Glomerular basement membrane reduplication and fibrinoid necrosis was focally noted. Electron microscopy demonstrated absence of electron-dense deposits or mesangial interposition excluding membranoproliferative glomerulonephritis. We believe that the glomerular lesions are secondary to congenital renal arteriovenous malformation. To our knowledge, bilateral arteriovenous malformation in infancy is not previously described.