Incidence and prevention of deep venous thrombosis occurring late after general surgery: randomised controlled study of prolonged thromboprophylaxis

Objective: To study the incidence of late deep venous thrombosis (DVT), and to evaluate a regimen of prolonged thromboprophylaxis after general surgery. Design: Randomised, controlled, open trial, with blinded evaluation. Setting: University hospital, Denmark. Subjects: 176 consecutive patients undergoing major elective abdominal or non‐cardiac thoracic operations, of whom 118 were eligible for evaluation. Interventions: Thromboprophylaxis with a low‐molecular‐weight heparin, tinzaparin, given for four weeks (n = 58), compared with one week (control group, n = 60). Main outcome measures: Presence of DVT established by bilateral venography four weeks after the operation. Results: The incidence of late DVT in the control group was 6/60 (10%, 95% confidence interval (CI) 4% to 21%). In the prophylaxis group it was 3/58 (5.2%, 95% CI 1% to 14%) (p = 0.49). Conclusion: Prolonged thromboprophylaxis had no significant effect on the incidence of DVT occurring late after general surgery. Copyright © 1998 Taylor and Francis Ltd.