PURPOSE: To determine the prevalence, resulting clinical decisions, and the positive predictive value (PPV) of venous filling defects detected on portal venous phase (PVP) CT. METHODS: Over a 3-year period, 42412 consecutive patients underwent a PVP abdominopelvic CT; of these, 348 reports mentioned a filling defect concerning for deep venous thrombosis (DVT) in the IVC, iliac, or common femoral veins. Ninety-three patients underwent a reference standard venous imaging study. RESULTS: The prevalence of venous filling defects in CT reports was 0.82% (n = 348). Reports worded with higher degrees of certainty were statistically more likely to result in treatment, while lower certainty was correlated with additional confirmatory imaging. The PPV for detection of DVT was 77%. The presence of peri-vascular stranding or vessel expansion increased the PPV of PVP CT to 95% and 100%, respectively. CONCLUSION: While the PPV for filling defects on PVP CT was modest, it was substantially improved if peri-venous stranding or vessel expansion was present.