A previously healthy 21-year-old man presented with back pain, bilateral extremity pain, and right lower extremity weakness, paresthesias, and swelling. Sonographic examination revealed diffuse deep vein thrombosis (DVT) in the femoral and popliteal venous system. CT imaging revealed hypoplasia of the hepatic inferior vena cava (IVC) segment with formation of multiple varices and collateral veins around the kidneys. Hematologic workup also discovered a factor V Leiden mutation, further predisposing the patient to DVT. The rare, often overlooked occurrence of attenuated IVC, especially in the setting of hypercoagulable state, can predispose patients to significant thrombosis.