CHANGING FEATURES OF PROXIMAL VEIN-THROMBOSIS OVER TIME

Recently, the sensitivity of impedance plethysmography (IPG) for the d iagnosis of acute deep-vein thrombosis (DVT) in symptomatic outpatient s has been questioned. In order to verify whether a change in the veno graphic pattern of DVT has occurred over years, accounting for the dec reased sensitivity of IPG, the authors compared two series of consecut ive venograms demonstrating proximal DVT, performed between 1984-1988 (166 patients) and 1990-1992 (140 patients). They evaluated both the e xtension and the occlusiveness of deep-vein thrombi in the two series. Moreover, changes in the referral characteristics of patients were in vestigated. In the second series of venograms a significant decrease i n thrombi extension, expressed by a lower prevalence of iliac vein thr ombosis (29% versus 43%; P = 0.0074) was observed; moreover, a signifi cant increase in the prevalence of nonocclusive thrombi (22% versus 8% ; P = 0.0004) was also recorded in the second series when compared wit h the first. During the study period, among the referral characteristi cs of patients, the authors observed both a significant decrease in th e prevalence of proximal DVT (from 31% to 24%; P < 0.01) and a slight and not statistically significant decrease in the median time elapsed between onset of symptoms and referral for objective testing (from eig ht and a half to seven days). In conclusion, proximal deep-vein thromb i are currently less extensive and occlusive than observed in the past . These results might depend on earlier referral of less symptomatic p atients and might explain the recently reported decrease in IPG sensit ivity for proximal DVT.