['A double-lumen catheter (DLC) is used as a temporary blood access in emergency haemodialysis and continuous haemodialysis. There are various reports concerning thrombosis related to use of DLC and other catheters. The objective of this study is to assess the incidence of venous thrombosis when using DLC in patients undergoing blood purification. Method. Forty-eight Japanese patients, hospitalized in the Saitama Medical University hospital from December 2004 to April 2005, who had DLC insertion as a temporary blood access for blood purification. The existence of a thrombus was determined using ultrasonography, before catheter insertion, and every 2 days after insertion up to 3 weeks. At the time of DLC insertion, general blood tests including plasma D-dimer, and serum C-reactive protein (CRP) were performed. When DLC was removed, plasma D-dimer and serum CRP were measured.', 'In 30 of 48 (62.5%) patients with DLC insertion as a temporary blood access for haemodialysis, venous thrombi with diameters>1.1 mm were detected by venous ultrasonography. No predictive factors were recognized except an increase in plasma D-dimer that was significantly higher in the patients with venous thrombus. The changes in plasma D-dimer were 3.54 (SE 0.8) microg/dl in patient with thrombus, and 0.29 (0.30) microg/dl in patient without thrombus (P=0.004).'] Is elevation of plasma D-dimer closely associated with venous thrombosis produced by double-lumen catheter in pre-dialysis patients?