First step: free the inferior vena cava (IVC) and aorta artery (AA) from the posterior peritoneum

To open the posterior peritoneum along the right renal lateral border, the dorsal part was dissected to free the kidney. Then, the posterior peritoneum was opened along the right side of the IVC, and the IVC and AA were dissected, carefully separating and ligating branch vessels (principally lumbar arteries and veins) sprouting from the AA and IVC. Isolation was continued upward to the vena cava foramen of the diaphragm and downward to the right common iliac vessels. The same operation was performed on the left side, opening the posterior peritoneum along the left renal lateral border and freeing the kidney. Then, the posterior peritoneum was opened along the left side of the AA upward to the aorta hiatus and downward to the left common iliac vessels to free the AA and IVC absolutely.