[The case for more active prevention of deep-vein thrombosis after major surgery (author's transl)].

The frequency of deep-vein thrombosis (DVT) determined by the 125I-fibrinogen test and confirmed by phlebographic studies, is 20 to 30 % in high-risk patients over the age of forty undergoing major surgery. Comparison of this figure with the incidence of clinically detected thrombosis (5 to 10 %) shows that physical signs are unreliable in the detection of this disease. The ultimate fate of these thrombi is unknown. The majority will probably disappear spontaneously; some will be responsible for the development of a "post-phlebitic syndrome" in the extremities and some will propagate and may produce a fatal pulmonary embolus. Besides the currently used physical methods of prophylaxis, some new pharmalogical techniques for the prevention of postoperative deep-vein thrombosis have been tested and advocated in neighbouring countries. Oral anticoagulants have been used routinely for many years by most Dutch surgeons but have never become very popular in other countries. They need extensive laboratory control and, in spite of this, up to 20 % overdosage bleedings have been recorded. As both the administration of low-dose subcutaneous heparin and IV dextran have been reported to provide effective prophylaxis against deep venous thrombosis, we decided to study and compare their efficacy in a randomized clinical trial in order to assess their practical value in daily surgical practice. 119 adult patients undergoing abdominal surgery have been investigated. They have been devided at random in three groups : a dextran 40 group (n=39), a heparin group (n=39) and a control group (n=41 patients). DVT was diagnosed by the fibrinogen uptake test in 21,9 % patients in the control group in 12,8 % patients in the dextran group, and in 10,2 % patients in the heparin group. For the highrisk patients over the age of 70, the administration of low dose SC heparin, as well as the administration of IV low molecular weight dextran significantly reduced the incidence of postoperative DVT in the lower extremities (p less than 0.05). The dextran 40 and heparin groups were not significantly different. The techniques are simple and do not need laboratory control. No deleterious side effects have been noted. A large-scale multicentre international, clinical trial (4121 patients) recently showed that low-dose heparin prophylaxis not only lowered the incidence of postoperative deep-vein trombosis without severely augmenting the risk of bleeding, but also significantly reduced the frequency of fatal pulmonary embolism in the postoperative period. It is suggested that the administration of low-dose subcutaneous heparin should become a routine prophylactic measure in daily surgical practice.