The Postoperative Dip in Peroperative Anticoagulation

Abstract

Summary and Conclusions1. A postoperative dip as measured by the Thrombotest or prothrombin time occurs after pecoperative anticoagulation on a therapeutic level with coumarin derivatives.2. This dip usually occurs on the first postoperative day.3. Estimations of the coagulation factors influenced by vitamin K1 revealed values which were near or under the critical bleeding level.4. It was found that a more or less impaired liver function after the operation was unable to counteract the increased postoperative consumption of coagulation factors.5. In all cases of perioperative anticoagulation three principles should be kept in mind in order to circumvent either bleeding or thrombosis.a) recognition of the existence of a postoperative dip.b) frequent postoperative estimations of the Thrombotest or the prothrombin time.c) correction of the anticoagulation to the therapeutic level by means of small doses of vitamin K1 and appropriate laboratory control.6. The danger of peroperative anticoagulation (haemorrhage) is mainly due to the postoperative dip and can, therefore, largely be prevented.