Patient Instructions

Blood draw

During a standard blood draw, blood is collected into color-coded tubes based on the type of test your physician has ordered. Approximately 3-7 milliliters (between a teaspoon and a tablespoon) of blood is required for each test. The number of tubes will be determined by the tests ordered. From the time you register, the process should take approximately 20 minutes. However, some tests are timed and may take longer.


Certain blood tests require you to fast 10-12 hours to improve the accuracy of those tests. This means you cannot eat or drink anything except for water during that time. You may continue to take your medications unless your physician says otherwise. Drinking water while fasting is important because it hydrates the veins and helps to make the blood draw easier. It is a good idea to bring a snack with you so once you’ve had your blood drawn, you may eat or drink something. If any of your tests require you to fast, you will be instructed by your physician.

View frequently asked questions.