Renal arteriovenous malformation mimicking hydronephrosis

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.

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.

Management of renal arteriovenous malformations: A pictorial review

Background

Arteriovenous malformations (AVMs) are communications between an artery and a vein outside the capillary level. This pathologic communication may be either a fistula, a simple communication between a single artery and a dilated vein, or a more complex communication, a nidus of tortuous channels between one or more arteries/arterioles and one or more draining veins. The latter type of lesion is most frequently seen in the extremities; in the kidney they tend to appear more rarely. The most common clinical presentation of renal arteriovenous malformations (RAVMs) is haematuria. Percutaneous treatment with selective endovascular techniques offers a minimally invasive, nephron-sparing option in comparison to the more invasive surgical approaches. The purpose of this pictorial review is to highlight the general lines of management and to show the range of imaging findings of the percutaneous treatment of RAVMs.

Methods

The imaging characteristics of a selection of cases of percutaneously managed congenital RAVMs are presented and the most common lines of approach are discussed.

Conclusion

The imaging spectrum of diagnosis and percutaneous treatment of RAVMs is presented in order to aid interpretation and endovascular management.

Teaching points

• Renal arteriovenous malformations are very rare lesions.

• Clinical expression is usually haematuria.

• Diagnosis is made with CT or MRI but the gold standard is digital subtraction angiography.

• Catheter-directed treatment with the use of coils or liquid embolics is minimally invasive, safe and effective.

Renal artery aneurysm mimicking renal calculus with hydronephrosis

A 51-year-old woman was found to have a left renal calculus with hydronephrosis. She underwent unsuccessful extracorporeal shock wave lithotripsy, leading to the recommendation that percutaneous lithotomy was necessary to remove the renal calculus. In view of the unusual shape of the calculus and absence of abnormalities in urine sediment, preoperative computed tomography and renal angiography were performed, which instead showed a calcified left renal artery aneurysm. Subsequent efforts to perform an aneurysmectomy also failed, eventually necessitating left nephrectomy. This case illustrates the pitfalls in the diagnosis of a renal artery aneurysm, which is a relatively common condition that may have unusual presentations. Hence, it is suggested that the possibility of a renal artery aneurysm be considered in the differential diagnosis when one detects a renal calculus with an unusual appearance. In addition, we propose that 3-dimensional reconstruction computed tomography be performed before considering surgical options for such renal calculi to rule out the possibility of a renal artery aneurysm.

Renal arteriovenous fistula simulating hydronephrosis: A case report

INTRODUCTION

Acquired renal arteriovenous fistulas (AVFs) include those that occur as a complication of renal biopsy.

CASE REPORT

The authors report the case of a woman with recent-onset grade I hypertension, who was referred to our staff for sonographic studies of the kidneys and urinary tract. Laboratory data revealed microhematuria and proteinuria <0.5 g/24 h, and renal function was borderline (MDRD GFR 58 mL/min). Renal sonography of the left kidney revealed an anechoic, arboriform area at the level of the pelvis, which was suggestive of hydronephrosis. The color Doppler examination showed turbulent flow within the anechoic area, with high-velocity arterial flow and arterialization of the venous waveform at spectral analysis. Selective renal angiography later confirmed the presence of a middle renal AVF with pseudoaneurysm, which had been provoked by a renal biopsy performed over 10 years earlier in another center. Since the patient was currently in good health, the prescribed management consisted solely of close clinical and US follow-up.

DISCUSSION

AV fistulas are among the most commonly diagnosed renovascular malformations. The case reported here underlines the importance of using color Doppler ultrasound when obstructive uropathy is suspected, especially in patients who have undergone renal biopsy.

An Unusual Cause of Haematuria: Renal Arteriovenous Malformation Mimicking Caliceal Dilatation at Ultrasonography

We report a 37-year-old woman admitted to the emergency service with macroscopic haematuria and flank pain due to renal arteriovenous malformation (AVM). Ultrasonography showed apparent dilatation of the left renal caliceal system, whereas intravenous pyelography (IVP) demonstrated multinodular pelvicaliceal impressions with no caliceal dilatation. The final diagnosis was established with conventional angiography. Renal AVM may mimic caliceal dilatation on ultrasonography. Demonstration of multinodular pelvicaliceal impressions at IVP and lack of caliceal dilatation are clues for the correct diagnosis in this particular situation.

[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.