What fraction of people with a DVT get a PE?

The risk varies depending on the location of the clot. The risk for a PE increases the higher up in the leg the DVT occurs. For example, a calf DVT has a lower risk of breaking off and becoming a PE than a clot behind the knee or one in the groin or pelvic veins. Essentially, the larger the vein with the clot, the greater the risk of developing a PE.