Abstract： Objective To determine the clinical significance of perioperative plasma D- dimer dynamic assays in predicting incidence of deep vein thrombosis (DVT) in patients undergoing major orthopedics operations.Methods A total of 92 patients undergoing major orthopedics operations (28 underwent total hip anthroplasty,40 received total knee anthroplasty,24 were treated with hip fracture surgery) were recruited from Zhengzhou Orthopedics Hospital between October 2009 and November 2010 and were subjected to measurements of plasma D- dimer levels via immunochromatogram assay during admission,at 2 hours postoperatively,and on days 1,2,3,4,6,8,10 and 15 postoperatively,for analysis of dynamic variation.Subjects were assigned into DVT group and non-DVT group based on the deep venous ultrasonography.Results As compared with preoperative levels,92 patients presented elevated plasma D-dimer levels postoperatively,which was over 2000 μg/L 2 h after operation.Ten patients were found to have continuous or progressive increase in plasma D- dimer,which peaked to (3588 ± 512) μg/L on day 1,sustained at high levels and retained as high as (2494±394) μg/L at day 15 postoperatively.By contrast,82 patients exhibited rapid fall in plasma D-dimer levels,with the peak concentration sustained for merely 3 days and average levels lower than 500 μg/L at day 4 postoperatively and thereafter.Above 10 patients (incidence rate:10.87％ ) were confirmed to have DVT (DVT group) and other 82 patients showed no evidence of DVT (non-DVT group).Plasma D-dimer of DVT group increased significant at 2 hours,and on days 1,2,3,4,6,8,10 and 15 postoperatively (all P＜0.05),but not preoperatively (P＞0.05) as compared with non- DVT group.Conclusion Dynamic plasma D- dimer monitoring is critical to timely diagnosis of DVT during perioperative period in patients undergoing major orthopedics operations.