title: Complicated inferior vena cava filter retrievals: associated factors identified at preretrieval CT.
abstract: OBJECTIVE
  To examine filter characteristics at preretrieval computed tomography (CT) that are associated with complicated inferior vena cava (IVC) filter retrieval procedures.
  
  
  METHODS
  This study was HIPAA compliant, and informed consent was waived. Institutional review board-approved retrospective review of IVC filter retrievals between January 2002 and July 2011 was performed to identify patients with preretrieval CT in whom a complicated retrieval was performed, as defined by use of nonstandard techniques, filter fracture, filter tip incorporation into the IVC wall, and retrieval failure. Age- and sex-matched control subjects with standard IVC filter retrieval were used for comparison. Preretrieval CT images were evaluated for tilt angle in mediolateral and anteroposterior directions, CT appearance of tip embedding, degree of filter strut perforation, and distance of filter tip from the nearest renal vein. Dwell time was also recorded. Statistical analysis was performed by using the Fisher exact test, Student t test, and Wilcoxon signed-rank test, depending on the variables being evaluated, as well as multivariate logistic regression.
  
  
  RESULTS
  Forty-eight patients with complicated retrievals and 48 control subjects with uncomplicated retrievals were evaluable for preretrieval CT characteristics. Mediolateral and anteroposterior tilt angle, degree of perforation, and dwell time were higher for the complicated versus non-complicated retrieval group (P < .01). Odds of complicated retrieval were increased 129-fold with CT appearance of tip embedding (P < .0001), with an odds ratio of 33 with a tilt angle of more than 15° in any direction (P < .0001), while perforation and dwell time increased risk of a complicated retrieval by 10.7 (P < .0001) and 2.3 (P < .05) times, respectively. Distance from renal veins was noncontributory.
  
  
  CONCLUSIONS
  CT appearance of tip embedding, increased tilt angle, higher-grade perforation, and longer dwell times are associated with complicated IVC filter retrieval. Therefore, preretrieval CT may be warranted in select patients for identification of these characteristics to tailor retrieval approach or to arrange a referral to a tertiary center if necessary.
authors.affiliation: Department of Radiology, Division of Interventional Radiology, Perelman School of Medicine at the University of Pennsylvania, 3400 Spruce St, Philadelphia, PA 19010, USA.
authors.forename: Lu Anne V
authors.initials: LA
authors.lastname: Dinglasan
authors.forename: John C
authors.initials: JC
authors.lastname: Oh
authors.forename: J Eric
authors.initials: JE
authors.lastname: Schmitt
authors.forename: Scott O
authors.initials: SO
authors.lastname: Trerotola
authors.forename: Richard D
authors.initials: RD
authors.lastname: Shlansky-Goldberg
authors.forename: S William
authors.initials: SW
authors.lastname: Stavropoulos
mesh_terms: D000293:Adolescent; D000328:Adult; D015897:Comorbidity; D020878:Device Removal / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015143:Philadelphia / Q000453:epidemiology; D011183:Postoperative Complications / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D011300:Preoperative Care / Q000379:methods; D015995:Prevalence; D011379:Prognosis; D012189:Retrospective Studies; D018570:Risk Assessment; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000706:statistics & numerical data*; D016306:Vena Cava Filters; D055815:Young Adult