Inferior vena caval invasion by renal cell carcinoma: false positive diagnosis by venacavography.

We reviewed the records of 22 renal cell carcinoma patients who were referred to this hospital to determine inferior vena caval extension of tumor. Preoperative radiological studies from referring hospitals and this institution were compared to the operative findings. Four cases of false positive inferior vena caval involvement on preoperative venacavograms performed and interpreted elsewhere were identified. In 3 of these cases a repeat preoperative inferior venacavogram performed at this hospital made the correct diagnosis. In the remaining case an inferior venacavogram was not repeated but no tumor was found at operation. One patient who did not undergo an operation was believed to have vena caval involvement by computerized tomography but venacavography was negative. Reasons for the false positive studies included suboptimal technique and misinterpretation of normal flow defects. Our technique for venacavography is presented. The importance of satisfactory preoperative radiological studies is stressed.