[Internal bleeding in patients on oral anticoagulants]

Five selected case reports of patients suffering from rather unusual bleeding complications during oral anticoagulant therapy are presented. The reported frequency of bleeding during oral anticoagulation varies greatly. An unacceptably high incidence of hemorrhages has been reported in North American studies of the early 1980ies. The therapeutic target INR of 2.5-4.9 in these series is comparable to that in European studies where bleeding occurred much less frequently. We suggest that the insensitive thromboplastin reagents used in North America are unsuited to guide coumarin dosage, because too many prothrombin time values were outside the INR target range. In contrast, most prothrombin time values in European studies where a sensitive thromboplastin reagent was used, were within the target range. A recent prospective investigation by 25 Swiss practitioners showed an acceptably low bleeding complication rate (2.1 hemorrhagic complications severe enough to necessitate hospitalization per 100 patient years). Observation of contraindications, regular control of the prothrombin time using a sensitive and correctly calibrated thromboplastin, participation of practitioners and hospital laboratories at quality control exercises and consideration of drug interferences with coumarins help to reduce the incidence of hemorrhagic side effects. In case of either a PT value outside the target range or manifest bleeding, the necessary measures have to be tailored to the individual situation considering the Quick value as well as the severity and localization of hemorrhage.