title: The patterns and distribution of residual abnormalities between the individual proximal venous segments after an acute deep vein thrombosis.
abstract: BACKGROUND
  The subsequent course of residual abnormalities after an acute deep vein thrombosis (DVT) can vary within individual venous segments. To investigate the pattern of response within the individual venous segment, we used sequential duplex scanning to determine whether certain segments are more likely to recanalize or remain occluded.
  
  
  METHODS
  The anatomic segments involved in 63 above-knee DVTs were examined with duplex scanning at 1 week, 1 month, 6 months, and 1 year after the acute event. The segments under investigation were the external iliac vein (EIV), common femoral vein (CFV), superficial femoral vein (SFV), and popliteal vein (PV). Reflux studies were performed at each follow-up examination. During the follow-up period the segments were examined to see whether they were occluded, partially recanalized, or totally recanalized and the development of reflux was noted.
  
  
  RESULTS
  Most DVTs were multisegmental with a total number of 171 sites involved. Initially, a greater number of segments were occluded (71%) than partially thrombosed (29%). The occluded segments were predominantly in the SFV and PV. At 1 year the thrombi had fully resolved in 60% of the venous segments, 27% remained partially recanalized, and 13% were occluded. The venous segments that resolved within the first 6 months had a higher rate of valvular competence than those that resolved from 6 months to 1 year. The SFV and PV had a higher incidence of valvular incompetence than the EIV and CFV. All venous segments that were partially recanalized at 1 year were found to have significant reflux. The SFV had the highest incidence of total occlusion at the end of 1 year (36%). Many of the occluded SFVs had established collateral pathways that displayed no evidence of reflux.
  
  
  CONCLUSIONS
  The lower extremity venous segments differ in respect to their tendencies to partially or fully recanalize or remain occluded. All partially recanalized segments displayed reflux. Fully resolved segments that recanalized within the first 6 months were more likely to have competent valves than those that recanalized after 6 months. In the presence of an occluded SFV, collateral pathways establish rapidly. No reflux was found in these collaterals.
authors.affiliation: Department of Anatomy, Trinity College, Dublin, Ireland.
authors.forename: A M
authors.initials: AM
authors.lastname: O'shaughnessy
authors.forename: D E
authors.initials: DE
authors.lastname: Fitzgerald
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003097:Collateral Circulation; D005260:Female; D006801:Humans; D007866:Leg / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D018616:Ultrasonography, Doppler, Duplex; D014654:Vascular Patency; D020246:Venous Thrombosis / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000503:physiopathology*