a 33-year - old female patient presented at the emergency room with epigastric pain , nausea , and vomiting that had persisted for a day . the patient had a history of child birth eight months prior , and had proximal deep vein thrombosis ( dvt ) on the left common femoral vein during the 36th week of pregnancy . an inferior vena cava ( ivc ) filter had been inserted instead of anticoagulation due to the high risk of bleeding during pregnancy . removal of the ivc filter was recommended one month after insertion , but the patient refused for personal reasons . on arriving at the emergency room , her vital signs were stable and the laboratory examination did not show abnormalities other than mild leukocytosis . the patient 's prothrombin time international normalized ratio value at the emergency room was 1.31 due to irregular intake of warfarin . a computed tomography ( ct ) scan revealed that one of the ivc filter legs had penetrated the ivc wall and caused a duodenal perforation ( fig . a protruding ivc filter leg was observed in the lumen of the third portion of the duodenum ( fig . 2 ) . in addition , the duodenum mucous membrane on the opposite side showed erythema , erosion , and nodular changes , resembling chronically progressing penetration . an emergency laparotomy was performed in order to remove the ivc filter and to repair the duodenum . because there were concerns regarding the possible ivc rupture during surgery , a cannula was placed in the superior vena cava to provide extracorporeal circulation when needed . also , the femoral artery and femoral vein were isolated for cannulation . the portions of the ivc and the duodenum , including the penetrations , were isolated behind the colon . when the duodenum was lifted up , we found the ivc filter leg between the ivc and the duodenum . we then cut the ivc filter leg and removed the ivc filter leg remnant from the duodenum portion . the ivc was found to be densely adhered to the surrounding tissue including the aorta , and fixed to the adjacent structures . we concluded that isolation and removal of the ivc filter leg remnant in the ivc were more dangerous due to the risk of rupture . the remaining leg protruding from the ivc side to the duodenum was cutoff and removed ( fig . 3 ) . after the surgery , ileus occurred and the patient started to eat by mouth after 14 days . the ivc filter is known as an effective and safe method for preventing fatal pulmonary thromboembolism in patients with deep vein thrombosis . the ivc filter is indicated in dvt patients when any of the following symptoms are present : contraindication of anticoagulation , major bleeding , need for surgery within 2 weeks , severe and prolonged thrombocytopenia , and recurrent dvt disease despite anticoagulation . complications related with the ivc filter can be categorized as insertion - related complications , device failure , and late complications . insertion - related complications include pneumothorax , hemorrhage , filter misplacement , excessive tilt , and vascular injury . late complications include recurrent pulmonary embolus , caval occlusion , filter migration , and filter leg perforation . the titanium greenfield filter showed a 3.5% perforation rate , the stainless steel greenfield filter showed a 4.4% rate , the bird 's nest filter showed a 38% rate , and the simon nitinol filter showed a 37% rate . most patients with perforations do not show any symptoms and the perforation rarely causes clinical problems . however , there are cases where the filter can damage surrounding organs and cause severe complications in the aorta , duodenum , ureter , or retroperitoneal space [ 4 - 6 ] . pulsation of the aorta and respiratory motion are thought to be the main cause of caval penetration of the filter leg . in our case , the cause of the ivc wall penetration seemed to be chronic progression of the ivc filter leg , nine months after the ivc filter insertion ; subsequently , it finally penetrated into the duodenum . based on the preoperative ct venography , the ivc flow was maintained and there was no dvt below the ivc level . also , based on the observations in the operation room , although cardiopulmonary bypass was in standby before surgery , removal of the ivc filter was thought to be more risky . thus , a partial resection of the ivc filter leg that was penetrating the duodenum was performed , and the ivc was reinforced . currently , the ivc filter is widely used and only 50% of them are removed from patients . most of the remaining ivc filters are asymptomatic and do not cause clinical problems . however , in order to prevent potential sequelae caused by ivc filter leg penetration , like that reported in this case , the removal of the ivc filter , when possible , is preferred .
the inferior vena cava ( ivc ) filter is known as an effective and safe method for preventing fatal pulmonary thromboembolism in patients with deep vein thrombosis . 
 usually , the remaining ivc filters are asymptomatic and do not cause clinical problems . 
 we report a case of duodenal perforation caused by a remaining ivc filter .