Hemorrhage during long-term anticoagulant drug therapy. II. Gastrointestinal hemorrhage.

Most of the gastrointestinal hemorrhages occurring during long-term anticoagulant drug therapy of 2,013 patients (reported in the literature) were caused by underlying lesions (44 to 77). Of the 44 lesions, only seven were diagnosed before treatment was started. Most of the episodes of hemorrhage occurred with the prothrombin activity at a so-called "safe" level. Closer investigation before the anticoagulant therapy was begun might have brought the underlying lesion to light.