 In the United Kingdom , professional guidelines give specific indications for thrombophilia testing . It is recommended that testing be done only after appropriate counseling , and hence the investigations are usually not performed at the time when thrombosis is diagnosed but at a later time . In particular situations , such as retinal vein thrombosis , testing is discouraged altogether because thrombophilia is not regarded as a major risk factor . In other rare conditions generally linked with hypercoagulability , such as cerebral venous thrombosis and portal vein thrombosis , there is insufficient data to state for certain whether thrombophilia screening is helpful , and decisions on thrombophilia screening in these conditions are therefore not regarded as evidence @-@ based . If cost @-@ effectiveness ( quality @-@ adjusted life years in return for expenditure ) is taken as a guide , it is generally unclear whether thrombophilia investigations justify the often high cost , unless the testing is restricted to selected situations . 
