The effect of low-dose heparin on hypercoagulability following abdominal aortic surgery

The effect of low-dose heparin on postoperative hypercoagulability was assessed using thrombelastography (TEG) in eighteen patients undergoing elective abdominal aortic surgery. Patients received unfractionated heparin 5000IU bd SC commencing on the first postoperative day. Native whole blood TEG was performed preoperatively and on day two postoperatively. A heparinase-modified TEG was performed at the same time as the native whole blood TEG on day two. There were no significant changes in the postoperative native whole blood TEG variables (r, K, alpha, MA) relative to preoperative controls. In contrast, there were significant decreases in r and K, and increases in alpha in the heparinase-modified TEGs postoperatively (P < 0.01). There were significant differences between the postoperative native whole blood and heparinase-modified TEGs for all TEG variables (P < 0.01). The results indicate that low-dose heparin reduces postoperative hypercoagulability following abdominal aortic surgery as assessed by thrombelastography.