 Apart from the abovementioned forms of thrombophilia , the risk of recurrence after an episode of thrombosis is determined by factors such as the extent and severity of the original thrombosis , whether it was provoked ( such as by immobilization or pregnancy ) , the number of previous thrombotic events , male sex , the presence of an inferior vena cava filter , the presence of cancer , symptoms of post @-@ thrombotic syndrome , and obesity . These factors tend to be more important in the decision than the presence or absence of a detectable thrombophilia . 
