An informed ER patient is one who has a basic understanding of the workings of the emergency room, and so can better appreciate the complex and wide range of medical care that is provided. ER physicians, like Dr. Josyann Abisaab, explain that a visit to the ER frequently involves one or more blood tests, which helps the ER team to accurately diagnose the source of the patient’s symptoms.

When a blood test is performed, the patient’s blood is placed into different colored tubes, each with a specific additive that relates to the test in question. A CBC (complete blood count) test uses a purple-top tube. The CBC measures the numbers of each of the three types of bloods cells: red blood cells, white blood cells, and platelets, in order to help diagnose specific illnesses and health conditions. A serum (the liquid/non-cellular part of the blood) test uses a tube with a red top, while a blue-top tube is used to test blood clotting.