[Renal arteriovenous fistulas after renal biopsy. Percutaneous embolization]

We report our experience relative to transcatheter percutaneous embolization of post-biopsy renal intraparenchymal arteriovenous fistulas in patients with chronic renal insufficiency.

We observed 5 patients affected with post-bioptic fistulas for possible embolization. In three cases the symptoms were represented by intermittent macro-microhematuria; one patient had hypertension of nephrovascular origin and one patient was asymptomatic. In all cases we performed angiography and it was possible to catheterize the peripheral afferent branch of the fistula with a superselective technique using a hydrophilic guide of 0.035 F and a hydrophilic Cobra catheter of 4-5 F. The occlusion was obtained by the positioning of Granturco metal coils: in 1 case we adapted a coil of 3 mm diameter and 1 cm length; in 3 cases 2 coils of 3 mm and in 1 case 2 coils of 3 mm and 1 coil of 5 mm diameter and 1 cm length were necessary. The success of the procedure was always checked with an immediate angiogram and color Doppler US after 48 hrs.

The diagnosis of arteriovenous fistulas was always confirmed by a preliminary angiography that demonstrated the normal anatomic disposition of the renal arteries except in one case in which the fistula was fed by a peripheral branch originating from an inferior polar artery. All the lesions were localized in the inferior pole, the site of biopsy, and ranged from 3 mm to 2.5 cm in diameter. We never had any difficulties in the positioning and placement of the coils. The arterial occlusion and exclusion of the fistula was accomplished in all cases. The induced parenchymal loss ranged from 10 to 30% of the renal volume. There was a complete disappearance of symptoms in 3 of the patients, with hematuria without any modification of the blood pressure values in the patient with hypertension. Considering the patient status renal function did not worsen after the embolization. Each patient was followed-up with color Doppler US every two months.

The intrarenal arteriovenous fistula represents a relative frequent complication of renal needle biopsy in patients with arterial hypertension and nephroangiosclerosis as risk factors. Embolization is a valid alternative therapeutic option to surgical treatments. The use of small size catheters permits the successful embolization also of peripheral lesions, reducing the induced parenchymal ischemia. We believe that among the embolization material available metal coils represent a valid solution as they are easily positioned and permit definitive occlusion without any risks of systemic venous microembolization.