The Life of a Blood Sample

Written by NS StaffJuly 30, 2011

If you're interested in becoming a nurse, you're likely interested in both helping people and learning more about science and the human body. Ever wonder just how many people play a role in testing a blood sample? Read on to see just how many medical professionals, including potentially you, help make safe blood testing happen.

See a list of schools/colleges offering nursing programs

view counter

At one point or another in life each of us has taken a blood test, whether it be to test for a certain disease, for specific blood counts, or just the few drops taken upon applying to donate blood. Blood tests are an extremely important tool in patient care, as they provide an internal picture of the body, and can be used to diagnose an illness or disorder, and subsequently determine or monitor a course of treatment. However, few people probably wonder what happens from the time the blood is drawn until they are presented with their results.

The life of a blood sample is interesting, to say the least. First, the blood must be collected. Blood may be drawn from a patient from three sources: a vein in the crook of the elbow, an artery, or if only a few drops are needed, a finger stick. The type of tests needed will determine the drawing site. Most tests are run from blood drawn from a vein, but if, for example, a doctor wants to run a test for blood gases, the sample will be drawn from the wrist, where the arteries carry more oxygen-rich blood.

Programs to Consider:


After the sample is drawn, either by a nurse or a phlebotomist, it is carefully labeled so as to prevent any chance of an error or mix-up. The samples are then taken to the lab and given over to the lab technician on duty. The technician will then check the samples to make sure that they are correctly labeled, record them on either a computer system or file, and then prepare them for testing. Most often this will include checking the levels of the different types of blood cells and a blood smear, which is a film of blood place on a slide, allowing the technician to look at the individual cells under a microscope and check for any irregularities. Sometimes the blood needs to be separated to test individual components. When this is necessary the blood is placed into a centrifuge, spinning the blood into its component parts, which vary in density. The technician can then test the specific parts of the blood, which can greatly increase the accuracy of results. Once the results are collected, the technician records them on the patient test file and returns them to the physician for assessment, upon which a course of action can be undertaken.

The most common blood test is a CBC, or complete blood count, which counts the number of each type of blood cells in a person’s blood. A CBC can diagnose anemia, identify abnormal platelet counts, or diagnose serious viral or bacterial infections. Another common blood test is the metabolic profile, which tests the body’s different metabolic functions. This test can diagnose illnesses from diabetes to kidney disease. Other tests include hepatitis screenings, STD and HIV screenings, and testing for malaria or other blood-borne diseases.

Blood samples play an important part in the world of medicine and patient care. From these small samples doctors can learn much about the way diseases function, and also how the disease responds to certain courses of treatment. It’s an amazing thing that so much can be learned from such a small sample.

See a list of schools/colleges offering nursing programs

Learn More About Your Future Career as a Nurse:

Nursing Career Summary
Salary & Compensation
Day in the Life of…
Job Outlook
Typical Career Path
Medical Assisting as a Pathway to Nursing
Profile of a Nurse
Nursing as Compared to Doctoring
Blood and Needles