The saline dilution test--a preoperative predictor of DVT.

In vitro dilution of blood with normal saline produces an increase in coagulability which can be accurately measured by the thrombelastograph. The degree to which the coagulability of an individual patient's blood is increased by such dilution appears to be directly related to that patient's risk of developing a postoperative deep venous thrombosis. In a small group of patients undergoing major abdominal surgery, a preoperative test based on the coagulability increase after in vitro saline dilution successfully predicted all those who subsequently developed a postoperative deep venous thrombosis on 125I-fibrinogen scanning.