title: Penetration of the inferior vena cava and adjacent organs after filter placement is associated with retrievable filter type and length of time in place.
abstract: OBJECTIVE
  Concern over local complications of inferior vena cava (IVC) filters exists, but little long-term data are available. Referrals for filter penetrations on computed tomography (CT) have increased with no standards for management. We reviewed postfilter CT findings in our institution.
  
  
  METHODS
  All patients receiving IVC filters between January 1, 2006 and December 31, 2009 with a postfilter CT were reviewed. Penetration was graded with a previously published scale. Filter indication, type, and subsequent encounters for abdominal or back pain were recorded.
  
  
  RESULTS
  A total of 591 patients had a filter during the study period. Of these, 262 had an adequate postfilter CT, comprising the study group. Indications were prophylaxis in 16.4% and venous thromboembolism in 83.6%. Of filters placed for venous thromboembolism, indications were absolute (inability/failure of anticoagulation) in 44.7% and relative in 55.3%. Retrievable filters made up 92.7% of the filters, and 7.3% were permanent type. Of the retrievable filters, 1.6% were retrieved. One hundred twenty (45.8%) filters had grade 2 or 3 penetration. Another 38.2% (100) had struts immediately adjacent to the external aspect of the IVC, which may represent tenting of the cava. Grade 2 or 3 penetration occurred in 49.0% of retrievable filters but only 5.3% of permanent filters (P = .0001). Grade 2 or 3 penetration occurred in 18.2% of filters less than 30 days old but in 57.3% of filters 30 days old or older (P < .0001). Thirty-two patients had subsequent encounters for abdominal or back pain, but none was conclusively related to penetration.
  
  
  CONCLUSIONS
  A majority of filters were placed for prophylaxis or relative indications and were retrievable type. Retrieval rate was low. Penetration of the IVC and adjacent organs was common and associated with retrievable type and length of time in place. It is unclear if most penetrations cause problems. Monitoring of penetrations with CT may be important to understand the natural history of this condition.
authors.affiliation: Division of Vascular Diseases and Surgery, The Ohio State University Medical Center, Columbus, Ohio. Electronic address: michael.go@osumc.edu.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Go
authors.affiliation: Division of Vascular Diseases and Surgery, The Ohio State University Medical Center, Columbus, Ohio.
authors.forename: Lucas
authors.initials: L
authors.lastname: Keller-Biehl
authors.affiliation: Division of Vascular Diseases and Surgery, The Ohio State University Medical Center, Columbus, Ohio.
authors.forename: Jean E
authors.initials: JE
authors.lastname: Starr