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 . 