Congenital Renal Arteriovenous Malformation Presenting With Gross Hematuria After a Routine Jog: A Case Report

Erin L Dames; Lay Guat Ng; Kiang Hiong Tay

Disclosures

J Med Case Reports. 2014;8(65) 

In This Article

Discussion

Gross hematuria and flank pain are among the most frequent complaints seen in urology outpatient clinics worldwide. Common causes of gross hematuria include urinary tract infection, urolithiasis and neoplasms of the genitourinary tract. Renal AVM are among the rare causes of gross hematuria. The consideration of this diagnosis early during diagnostic workup was noted to be paramount to management in view of the short chronology of the disease process and the potential for rapid clinical deterioration.

Renal AVM can be idiopathic, congenital or acquired, and are usually differentiated by their angiographic configuration. Acquired renal AVM (more frequently referred to as arteriovenous fistulas) are the most common type (up to 75% of all cases), frequently due to iatrogenic trauma such as renal biopsy or surgery. Other causes include blunt or penetrating trauma, pyelonephritis and renal cell carcinoma. Such cases are characterized in imaging studies as a solitary communication between an artery and a vein. Congenital renal AVM make up about 25% of all cases, and usually present in the third to fourth decade of life. They appear on angiography as lesions resembling angiomas or tortuous veins with multiple communications between arteries and veins, and are sometimes associated with genetic disorders such as hereditary hemorrhagic telangectasia.[2] Idiopathic renal AVM only comprise up to 5% of all cases, with similar angiographic appearance to that of the acquired type in the absence of an apparent cause. Idiopathic renal AVM are thought to be caused by spontaneous erosion or rupture of a renal artery into a neighboring renal vein.

While many renal AVM are diagnosed as incidental imaging findings in the investigation of hypertension or microscopic hematuria, there are few documented cases of patients initially presenting with gross hematuria with clots. This is sometimes associated with colicky pain, tenderness or a feeling of fullness in the flank region. Signs that may raise suspicion of a renal AVM include a continuous bruit or, less specifically, a palpable mass over the flank. Other more infrequent presentations may include symptoms or signs of congestive heart failure from high-output fistulas or hypotension from massive hematuria.

In the case reported, our patient's presentation with a first episode of exercise-induced hematuria on a background of preexisting hypertension painted a nonspecific picture with regard to the investigation of this episode. The ultimate development of symptoms such as flank pain and recurrent acute bladder tamponade due to clot retention lent more clues to the diagnosis of renal AVM, particularly in the absence of any radiological clues suggestive of other urologic pathology. Urolithiasis (with or without stone passage) can present like the current case with symptoms such as gross hematuria and flank pain, which was thought to be the initial diagnosis for our present case upon radiologic and cystoscopic examination. However, the persistence of symptoms and clinical deterioration in our present case compelled a second diagnostic approach and hence a decision was made to perform CT angiography. The other common differential diagnoses for urinary tract hemorrhage, genitourinary tumors (including malignancies of the bladder, ureter and prostate), can present with similar symptoms and signs, and the lack of radiologic, cytologic and endoscopic findings early in the diagnostic process were key in excluding this as a cause for urinary tract hemorrhage in the present case.[3]

Investigation of patients with renal AVM would be directed depending on their presentation and associated complaints. A complete blood count should be included in the investigational profile of a patient who presents with gross hematuria as a means of monitoring blood loss. Coagulation profiles are useful in determining the presence of any contributing coagulopathies. Renal function testing may be indicated in the analysis of hypertensive patients. Urine testing for microscopy, culture and cytology are indicated in patients presenting with hematuria to uncover any underlying infections, glomerulonephritides or malignancy.

Imaging studies remain an important tool in the diagnosis of renal AVMs. Ultrasonography with color duplex studies tend to be the first line of imaging studies used in the diagnosis of renal AVM in some centers. Findings on color duplex ultrasound scans include turbulent blood flow with increased velocity and increased turbulent diastolic flow into the feeding artery or arterial flow moving in opposite directions in a pair of adjacent vessels.[4] CT urography comprising plain, arterial, nephrographic and pyelographic phase images is a standard first-line imaging modality in the context of gross hematuria in many centers. In our center, the current CT urography protocol comprises plain, nephrographic and pyelographic phase images. This is geared toward diagnosis of the more common causes of hematuria such as calculi and tumors; however, its sensitivity is reduced by the absence of an arterial phase study. While digital subtraction angiography remains the gold standard in the diagnosis of AVM, it is not a first-line modality in view of its invasive nature. This modality is only used in the setting of inconclusive noninvasive imaging findings and with the intention to perform endovascular treatment.[5] Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) can be useful noninvasive tools in diagnosis, but are more costly and time-consuming than CT angiography.

Principles of management of renal AVM are dependent upon the presentation of the patient. In the case presented, immediate management included stabilization of our patient and urgent bladder decompression and manual bladder irrigation to relieve acute bladder tamponade. In patients presenting with symptomatic anemia and hypovolemia, immediate treatment would mandate the replenishment of blood and fluid reserves.

Conservative treatment including bed rest and symptomatic treatment can be initiated with some degree of safety in some cases of asymptomatic small renal AVM. Spontaneous regression of renal AVM secondary to renal biopsy has been noted, and there have previously been documented cases of spontaneous regression of congenital renal AVM.[6] However, a large number of cases are symptomatic on presentation, necessitating definitive treatment.

Minimally invasive percutaneous transarterial embolization therapy is the first line in the treatment of renal AVM. Embolization can be performed using different materials such as glue, the Onyx® liquid embolic system (Micro Therapeutics, Inc., Irvine, CA, USA), alcohol, gelatin sponges and foams, and PVA particles. Disadvantages of embolization therapy include the risk of nephropathy secondary to the contrast used during radiographic evaluation as well as the possible need for repeat sessions.

Surgical treatment of renal AVM is reserved for cases of large cirsoid malformations, cases intractable to medical and/or endovascular therapy and cases related to malignancy; there have been documented cases of renal AVM requiring urgent nephrectomy.[7] Moreover, nephrectomy has been noted to hold a certain degree of safety in giant renal arteriovenous high-output fistulas, particularly in patients with unfavorable anatomy such as vena caval fistulae.[8] While total nephrectomy would serve as a curative measure,[9] long-term complications including the risk of progressive renal impairment must be considered, especially in the setting of preexisting kidney disease and chronic illness. Partial nephrectomy plays a role in the treatment of smaller, polar renal AVM, including those associated with small renal cell carcinomas. Its role continues to be evaluated in this rare entity, particularly with current therapies stressing nephron sparing and preservation of as much renal function as possible. Ligation of feeding vessels has been implemented in the surgical treatment of smaller, more peripheral AVM. However, such a technique is technically challenging and rarely necessary in the advent of current skills in partial nephrectomy.[9]

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