Coagulation changes during major surgery and relationship to post-operative deep vein thrombosis.

Nineteen patients undergoing aortic surgery during which 5,000 units of heparin were given intravenously were compared with 39 patients undergoing laparotomy or herniorrhaphy. There was an expected significant reduction in coagulability as measured by thrombelastography in those patients undergoing aortic surgery. Moreover, the early post-operative deep vein thrombosis (DVT) rate was significantly less. This implies that a reduction in coagulability by I.V. heparin during surgery is associated with a lower incidence of early post-operative deep vein thrombosis. Among the laparotomy and hernia group who developed a DVT, coagulability was significantly greater both before and during the operation and on the first post-operative day.