title: Variations in lower limb venous anatomy: implications for US diagnosis of deep vein thrombosis.
abstract: OBJECTIVE
  To retrospectively review bilateral venograms free of thrombus to evaluate the frequency and types of variations seen in venous anatomy.
  
  
  METHODS
  A retrospective review of 404 bilateral (808 limbs) lower limb venograms obtained from medical patients participating in a thromboprophylaxis clinical trial and found to be free of thrombus was performed. Venograms were evaluated according to predetermined criteria for the presence of duplication of vessels and inter- and intraindividual variations in venous anatomy. Variations were assessed with analysis of variance and chi2 tests.
  
  
  RESULTS
  Two vessels were seen in the popliteal fossa on 337 (42%) of 808 venograms, and 41 (5%) were true duplicated popliteal veins. There were 253 (31%) duplicated superficial femoral veins (SFVs), with 12 (1.5%) being complex duplicated systems. Of 265 duplicated SFVs, 138 (52%) began in the midthigh region and 80 (30%), in the adductor canal region. The duplicated vessel was medial to the main SFV in 122 (46%), lateral in 131 (49%), and both (ie, triplications) in 12 (4.5%). The length of the duplicated SFV ranged from 1 to 35 cm; 6-15 cm was the most common length in 162 (62%) SFVs. There was no significant association between the incidence of anatomic variations and age or sex (P >.1). The presence of multiple vessels in one leg was strongly correlated with the probability of occurrence in the other leg (P <.001).
  
  
  CONCLUSIONS
  Variations in lower limb venous anatomy are common and have important implications for the US diagnosis of deep vein thrombosis.
authors.affiliation: Department of Radiology, King's College Hospital, Denmark Hill, London SE5 9RS, England. dan.quinlan@consultoberon.com
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Quinlan
authors.forename: Raza
authors.initials: R
authors.lastname: Alikhan
authors.forename: Philip
authors.initials: P
authors.lastname: Gishen
authors.forename: Paul S
authors.initials: PS
authors.lastname: Sidhu
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D016009:Chi-Square Distribution; D005260:Female; D005268:Femoral Vein / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D006801:Humans; D007866:Leg / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D010690:Phlebography; D011152:Popliteal Vein / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D012189:Retrospective Studies; D014463:Ultrasonography; D020246:Venous Thrombosis / Q000000981:diagnostic imaging*