Abstract
OBJECTIVE: This study aimed to characterize radiographic characteristics on computed tomography venography and risk factors of inferior vena cava thrombosis (IVCT) in situ after retrievable vena cava filter (VCF) placement. METHODS: Between September 2018 and June 2023, a single-center retrospective cohort study was conducted in patients with or without IVCT in situ following VCF placement. Patient baseline demographics, presentation of lower extremity deep vein thrombosis (LEDVT), thrombus characteristics, concurrent pulmonary embolism, comorbidities and risk factors for LEDVT, and IVCT and VCF-related information were collected and analysed. Univariable analysis followed by multivariable analysis was performed to evaluate the odds ratio (OR) with a 95% confidence interval (CI). RESULTS: One hundred and seventeen eligible patients were included, regionally isolated filling-defect surrounding the support pillars of VCF and contacting inferior vena cava (IVC) wall on computed tomography venography images were identified, clots were more frequently found on the minor axis or anterior wall of IVC. Univariable analyses suggested that the incidence of IVCT in situ (31.6%, 37/117) was closely associated with age (P = .001), thrombus limb (left (P = .001) and bilateral side (P = .001)), hypertension (P = .008), filter shapes (P < .001), short IVC diameter (P = .009) or magnification percentage (P = .004), and long IVC diameter (P = .006). Multivariable analyses suggested that bilateral side LEDVT (OR, 4.92; 95% CI, 1.56-15.51; P = .007) and increased short IVC magnification percentage (OR, 1.01; 95% CI, 1.00-1.03; P = .013) statistically significant increase the IVCT in situ risk, whereas increased age (OR, 0.96; 95% CI, 0.94-0.99; P = .013) and short IVC diameter (OR, 0.87; 95% CI, 0.77-0.98; P = .026) were associated with decreased odds against IVCT in situ. CONCLUSIONS: IVCT in situ represents regionally isolated filling-defect at points of filter contact with IVC wall. Bilateral side LEDVT and increased short IVC magnification percentage may be potential risk factors impacting the occurrence of IVCT in situ, while increased age and short IVC diameter may decrease the incidence of IVCT in situ and seem to be protective factor against IVCT in situ emergence.