Background : Patients undergoing surgery with prolonged general anesthesia or a period of limited mobility postoperatively, or both, face a high risk of thromboembolism. Surgical procedure is considered as the third most common risk factor for thromboembolism after old age and obesity.

          Aim : To assess the value of enoxaparin in prophylaxis of venous thromboembolism and possible complications in comparison to Heparin in high risk patients undergoing general surgery.

          Patient and Methods : In the period between March 2003 and May 2005; 200 patients admitted for different surgical procedures were randomized into 2 groups: group A: where standard heparin was used as anticoagulant drugs and group B: where enoxaparin was used as prophylactic anticoagulant drug, pre and postoperative clinical and laboratory assessment was done in addition to Doppler ultrasound for deep lower limbs veins.

          Results : The age of patients in both groups ranged from 40-82 years with a mean preoperative hospitalization of 6.1 days and a mean operative duration 95 minutes, all patients were obese with other risk factors. Bleeding complications occurred in 30 patients group A and 16 patients in group B, deep venous thrombosis occurred in 10 patients ( 5%) , 8 of them were asymptomatic (4 in each group) and diagnosed by colour Doppler and 2 patients in group A were symptomatic and diagnosed clinically.

Conclusions : Low molecular weight heparin (enoxaparin) is more effective and safe than unfractionated heparin, but with higher coasts in postoperative deep venous thrombosis prophylaxis.