Table 2. Mayo Clinic RCC tumor thrombus level classification system and potential surgical approach.

Level	Description	Surgical approach to gain control central to tumor thrombus
0	Limited to renal vein or its tributaries	Renal vein ligation
I	Extends into IVC but <2 cm above renal vein orifice	Milking of IVC tumor thrombus into renal vein followed by renal vein ligation
II	Extends into IVC, >2 cm above renal vein orifice but below hepatic veins	Some mobilization of liver (ligation of accessory hepatic veins draining caudate lobe), clamping of intrahepatic IVC, clamping of infrarenal IVC and contralateral renal vein
III	Extends above hepatic veins but below diaphragm	Extensive mobilization of liver including ligation of diaphragmatic attachments, clamping of suprahepatic IVC with adjunctive venovenous or cardiopulmonary bypass
IV	Extends above diaphragm	Involvement of cardiothoracic surgery, potential thoracotomy and open-heart surgery

RCC, renal cell carcinoma.