Two hundred patients coming for surgery who are taking anti-platelet medications will be enrolled in this study as a pilot, to determine the feasibility for a larger study. A simple blood test for clotting function will be done after surgery. Patients will be assessed daily during their hospital stay to determine if they have any clotting or bleeding complications. For analysis, groups will be divided into normal and increased or decreased ability to make a blood clot based on the TEG® and PMA™ test done. Complications will be recorded for each group and analyzed to determine if there is any difference between groups.