title: Iliac vein compression as risk factor for left- versus right-sided deep venous thrombosis: case-control study.
abstract: OBJECTIVE
  To determine if compression of the left common iliac vein (LCIV) by the right common iliac artery is associated with left-sided deep venous thrombosis (DVT).
  
  
  METHODS
  This institutional review board-approved case-control study was performed in a cohort of 230 consecutive patients (94 men, 136 women; mean age, 57.5 years; range, 10-94 years) at one institution who had undergone contrast material-enhanced computed tomography of the pelvis prior to a diagnosis of unilateral DVT. Demographic data and information on risk factors were collected. Two board-certified radiologists determined iliac vein compression by using quantitative measures of percentage compression {[1 minus (LCIV diameter at point of maximal compression/distal right common iliac vein diameter)] times 100%}, as well as qualitative measures (none, mild, moderate, severe), with estimates of measurement variability. Logistic regression analysis was performed (independent variable, left vs right DVT; dependent variable, iliac vein compression). Cutpoints of relevant compression were evaluated by using splines. Means (with 95% confidence intervals [CIs]) and odds ratios (ORs) (and 95% CIs) of left DVT per 1% increase in percentage compression were calculated.
  
  
  RESULTS
  Patients with right DVT were more likely than those with left DVT to have a history of pulmonary embolism. Overall, in all study patients, mean percentage compression was 36.6%, 66 (29.7%) of 222 had greater than 50% compression, and 16 (7.2%) had greater than 70% compression. At most levels of compression, increasing compression was not associated with left DVT (adjusted ORs, 1.00, 0.99, 1.02) but above 70%, LCIV compression may be associated with left DVT (adjusted ORs, 3.03, 0.91, 10.15).
  
  
  CONCLUSIONS
  Increasing levels of percentage compression were not associated with left-sided DVT up to 70%; however, greater than 70% compression may be associated with left DVT.
  
  
  BACKGROUND
  http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12111580/-/DC1.
authors.affiliation: Johns Hopkins Hospital, Baltimore, Md, USA.
authors.forename: Anand
authors.initials: A
authors.lastname: Narayan
authors.forename: John
authors.initials: J
authors.lastname: Eng
authors.forename: Lemore
authors.initials: L
authors.lastname: Carmi
authors.forename: Siobhan
authors.initials: S
authors.lastname: McGrane
authors.forename: Muneeb
authors.initials: M
authors.lastname: Ahmed
authors.forename: A Richey
authors.initials: AR
authors.lastname: Sharrett
authors.forename: Michael
authors.initials: M
authors.lastname: Streiff
authors.forename: Josef
authors.initials: J
authors.lastname: Coresh
authors.forename: Neil
authors.initials: N
authors.lastname: Powe
authors.forename: Kelvin
authors.initials: K
authors.lastname: Hong
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D002648:Child; D003287:Contrast Media; D005260:Female; D006801:Humans; D007472:Iohexol; D016015:Logistic Models; D008297:Male; D062108:May-Thurner Syndrome / Q000150:complications* / Q000000981:diagnostic imaging*; D008875:Middle Aged; D011655:Pulmonary Embolism / Q000209:etiology; D012307:Risk Factors; D014057:Tomography, X-Ray Computed; D014283:Triiodobenzoic Acids; D020246:Venous Thrombosis / Q000000981:diagnostic imaging* / Q000209:etiology*
chemical_list: D003287:Contrast Media; D014283:Triiodobenzoic Acids; D007472:Iohexol; C044834:iodixanol