Following a L ab S ample

1. Following a Lab Sample What happens after blood is drawn for testing by a diagnostic lab?

2. Lab tests ordered by doctors for their patients may require: • Blood be drawn from a vein in the arm (venipuncture) or a finger stick. • A throat culture (taken by a swab rubbed against the back of their throat). • A urine sample, or another sample of body fluid • A piece of tissue (biopsy). • Once the sample is obtained, testing begins in the diagnostic laboratory where trained lab technicians use various methods to analyze the sample.

3. Sample collection • It is important that a doctor, nurse, or another medical professional correctly collects the sample. In this picture, a phlebotomist has inserted a needle into a vein on the outer portion of the arm near the elbow to draw a blood sample.

4. Sample Labeling • Once the blood is drawn, the tube is labeled. In many labs, the label will be pre-printed with the patient’s name, identification number, and number assigned to that specimen. It is essential to label the tube properly before leaving the patient’s side.

5. Documenting • Once the specimen arrives in the lab, the blood sample will be logged into the laboratory's tracking system. The tube label contains all the information necessary to ensure that the sample is run through the appropriate tests and the eventual results are matched to the patient. Usually, a form listing the patient’s and doctor’s name and address is sent with the sample so the results can be sent back to the doctor.

6. Processing • Depending upon the tests that have been ordered, the blood sample may be processed before it is analyzed. Most routine laboratory tests are performed on either plasma or serum. Plasma is the liquid portion of blood. It is separated from the cellular portion of blood by rapidly spinning the specimen in a centrifuge for several minutes. The plasma, which has a light yellow color, appears at the top of the tube, while the blood cells are at the bottom.

7. Processing Cont. • Serum is plasma that has been allowed to clot. It is prepared in the same way as plasma - however, the blood is collected into a tube with no anticoagulant. While spinning in the centrifuge, the clot moves with the cells to the bottom of the blood collection tube, leaving the serum on top. • If the test requires whole blood (e.g., a complete blood count), the sample can be analyzed directly without further processing.

8. Analyzing • In most cases, an instrument, appropriately called a blood analyzer, analyzes the blood sample. In this picture, the tube of blood is being placed directly into the machine. This particular state-of-the-art analyzer is capable of running batches of samples -- up to 120 samples per hour.

9. Results • With the latest technology in analyzers comes the ability to generate the results electronically and graphically. In this case, the results will be sent via email electronically to the doctor. In many situations, results are printed and then faxed to the doctor. If the results indicate the patient may be very ill, the laboratory will call the doctor with the results.

10. Results Cont. • The length of time between the drawing of the blood and when the doctor gets the results can vary greatly, from as little as a few minutes to as much as several weeks. • Urgency, geographic distances, processing schedules, complexity of the test, and other factors can have a great effect on time.