<prompt> Deep vein thrombosis is seen in all except one:Prolonged immobilizationSubungual melanomaPregnancyMajor surgical operation.  <response>: Ans. is b ie Subungual melanoma Risk factors for venous thromboembolism Patient FactorsDisease or surgical procedureAgeTrauma or surgery, especially of pelvis, hip, lower limbObesityMalignancy, especially pelvic, abdominal metastaticVaricose veins superficial thrombophlebitisHeart failureImmobilityRecent myocardial infractionPregnancyParalysis of lower limbsPuerperiumInfectionHigh-dose oestrogen therapyInflammatory bowel diseasePrevious deep vein thrombosis or pulmonary embolismNephrotic syndromeThrombophiliaPolycythaemicaDeficiency of anti-thrombin III, protein C or protein SParaproteinemiaAnti-phospholipidParoxysmal nocturnal hemoglobinuria antibody or lupus anticoagulant Behcets disease Homocystinemia 