Vascular malformations and arteriovenous fistulas of the kidney.

Vascular malformations of the kidney are disease processes that involve renal veins and arteries and include congenital arteriovenous malformations (AVMs) and arteriovenous fistulas. AVMs are congenital communications between arteries and veins with a vascular nidus that bypass the capillary bed. Congenital AVMs are rare and subclassified in cirsoid, angiomatous, and aneurysmal types. Congenital AVMs are different from iatrogenic or traumatic arteriovenous fistulas (AVF), which are characterized by a single direct communication between an artery and a vein without an intervening vascular nidus. These lesions may present with a wide range of signs and symptoms that vary from hypertension to renal masses. Imaging is valuable in the detection and characterization of AVM and AVF. The presence of arteriovenous shunting characterizes AVM and AVF. These lesions represent an important group of entities for diagnostic consideration, and understanding the vascular anatomy helps in guiding for proper treatment. This article describes the imaging features of each lesion that help to differentiate it from the others and the endovascular therapies to treat these vascular processes and their possible complications.