OBJECTIVE. Since the previous comprehensive radiology review on coagulation concepts that was done in 1990, many studies have been published in the medical and surgical literature that can guide the approach of a radiology practice. The purpose of this article is to provide an analysis of these works, updating the radiologist on proper use and interpretation of coagulation assessment tools, medications that modify the hemostatic system, and the use of transfusions prior to interventions. CONCLUSION. The basic tools for coagulation assessment have not changed; however, results from subspecialty research have suggested ways in which the use of these tools can be modified and streamlined to safely reduce time and expense for the patient and the health care system.