Section 7: Specimen Handling and Laboratory Processing

Special Handling

Some tests require special handling. The specifications to follow can be when you are performing the venipuncture, and they might be after you have collected the sample. As stated before, be sure you are prepared to draw, handle and prepare the entire test before you begin the venipuncture. If you have questions, get the answers before starting. You may need to ask a supervisor or look up special instructions in the test directory provided by your employer. Many times the lab your office is associated with will provide directories like these.

Fasting Specimens

When a patient is in a fasting state this is called the "basal state." Some tests require a patient to fast for 8-12 hours before the blood draw. Oftentimes water is okay (and helpful) to drink for blood work. Be sure to double check what kind of fasting and for how long. Your job is often to verify the patient has prepared properly as you often will not be there prior to giving them instructions. Some labs will not accept a sample if the patient was supposed to be fasting and didn't. Always note on their requisition their fasting status. If they are getting blood drawn after a meal this is called "postprandial."

Test Examples:

Lipid Panels
Glucose Tests

Timed Specimens

Time specimens are just like they sound like, time specific. This means that the draw must happen at a certain time of day or after a certain event such as drinking a glucose drink. It also might be a timed test, such as a series of draws drawn at specific times over a few hours.

Test Examples:

Hormone tests like cortisol drawn in the evening and morning, or testosterone drawn in the morning
Monitoring the changes in a patient's condition, such as hemoglobin, glucose or insulin levels as they change
- The Oral Glucose Tolerance Test (OGTT) is a prime example of this. This is a test that is used to diagnose diabetes. There is a 1 hr, 2hr, 3 hr and 5 hr test. The patient is given a concentrated measured glucose drink that comes in 50, 75, 100, and 150 gram dose sizes. The patient has a baseline blood draw before drinking the glucose drink and then they must complete drinking it in the next 5 minutes. Blood samples are taken hourly. The patient must be fasting 10-12 hours for this test.
- The Insulin Resistance (IR) test is very similar to the OGTT. It's a 2 hour long test with blood draws every half hour.
Medication and therapeutic drug levels for monitoring and determining dosing
- This therapeutic drug monitoring blood levels of certain medications ensure the patient's safety while taking the drug. The blood draw is supposed to line up with the troughs and peaks of the medication. Trough is the lowest chemical blood level and the peak is the highest. It is essential for the lab to know the time of the last dose of medication for the physician to safely and accurately prescribe more doses or changes to prescriptions.

Warmed Specimens

Some tests are going to require the sample to be kept warm until the serum is separated. The blood is collected in a pre-warmed tube. The tube can be warmed in an incubator or with a chemical hand warmer and then sits to clot with the blood in it for 30 minutes. These are usually red top tubes.

Test Examples:

Cold agglutinin
- Cold Agglutinin are antibodies produced in response to a mycoplasma pneumonia infection. These antibodies attach to the red blood cells in temperatures that are colder than body temperature. So to keep the antibodies in the serum, the sample must be kept warm.
Cryofibrinogen
Cryoglobulin

Chilled Specimens

Opposite of warming, some samples are chilled immediately after collection by putting it in crushed ice water. It must then be immediately transported to the lab for testing. These tests are run STAT. Samples should never be placed directly on dry ice.

Test Examples:

Ammonia
Lactic acid
Arterial blood gas (ABG)
- This test is not drawn by a phlebotomist as it is not drawn from a vein but instead an artery. Usually a respiratory therapist, nurse or physician will draw this test from the radial artery. The test must be run within 15 minutes of collection. Artial draws are primarily used to determine blood pH levels, blood carbon dioxide levels, blood oxygen levels, and blood bicarbonate levels.
Gastrin
Glucagon
Parathyroid Hormone
PT/PTT

Light-Sensitive Specimens

Some tests cannot be exposed to light or results could be affected. To avoid exposure to light the tubes can be wrapped in aluminum foil immediately after collection. There are amber transer tubes to pour serum or plasma into once centrifuged and also amber biohazard transport bags.

Test Examples:

Bilirubin
Vitamin B12
Urine Porphyrins
Carotene
Red Cell Folate
Serum Folate
Vitamin B6

PRe-analytical errors

Pre-analytical errors are errors that occur before the specimen is analyzed or before the test is run. These are errors that can happen before, during or after the blood draw. CLSI estimates that 46%-68% of lab errors are pre-analytical.

THE MOST CRITICAL ERROR A PHLEBOTOMIST CAN MAKE IS INCORRECTLY IDENTIFYING THE PATIENT BEFORE COLLECTING THE SAMPLE.

Here are some common pre-analytical errors to avoid making:

Before the Collection

Patient misidentification
Improper time of collection
Patient is not fasting, or fasting incorrectly
Medication interference
Improper site preparation
Poor coordination with other treatment plans

During the Collection

Tourniquet left on too long
Hemolysis
Wrong order of draw
Lack of or incorrect inversion of tubes
Faulty technique
Inadequate quantity of blood

After the Collection

Not separating serum or plasma from cells
Using a serum separator when not permitted
Delayed processing
Exposure to light
Improper storage conditions
Clots
Temperature fluctuations

LAboratory Processing

Depending on where you work, you will most likely be required to learn some laboratory processing as well as venipuncture collection. This can include centrifuging blood samples, and creating blood smears (slides).

Centrifuge

To separate the formed elements (cells) from the serum or plasma, the blood sample must be spun down in a centrifuge. A centrifuge machine is used for this process. The machine holds the tubes and spins them at a high rate of speed measured in rotations/revolutions per minute, or RPMs. The most important thing to note when loading a centrifuge is that it must be balanced. You must place a tube of equal size and volume of fluid (blood or water) directly opposite of one another. OSHA regulation requires the lid of the centrifuge to lock while it is in motion. Each centrifuge must be calibrated annually by a calibration technician. The RPM setting and time in the centrifuge will depend on the sample being spun. Make sure your samples that need to be clotted before spinning are completely clotted.

Microscope

Another device found in the lab is a microscope. A microscope is used to magnify blood or urine or other tissue to make health determinations. Microscopes should be kept clean and covered when not being used. Although using the microscope requires additional training you may be asked to prepare blood smears for a technician to examine under the microscope. Watch this video to learn how to prepare a slide.

Clinical LABORATORY sections

Although you may not work right in a lab, it is important to learn the different sections of a lab since often blood samples you collect are sent to labs for processing.

Hematology Section- This section examines and tests the blood's formed elements (the red blood cells, white blood cells and platelets. Disorders and infections are detected and monitored in hematology. In larger labs, the coagulation section is separate but in most it is apart of the hematology section. Coagulation evaluates hemostasis.

Chemistry Section- Chemistry is one of the bigger and more extensive parts of a lab. It is often divided up into several areas such as electrophoresis (Chemical components of blood), toxicology, and immunochemistry.

Blood Bank Section- This section is where blood is collected, stored and prepared for transfusion. The blood may be separated into components like packed cells, platelets, fresh frozen plasma and cryoprecipitate. Proper patient identification is crucial.

Serology (Immunology) Section- In this section tests are performed to evaluate the patient's immune response to antibodies. Serum is used to test for the presence of antibodies against bacteria, viruses, fungi, parasites, and autoimmunity.

Microbiology Section- Microbiology is responsible for detecting microorganisms that cause disease. Culture and Sensitivity (C&S) is a primary test performed in this section. Results usually take 24-48 hours as cultures have to be prepared and grown in an incubator. Some tests like tuberculosis or fungi take several weeks to grow. Based on the results, providers are able to determine what antibiotics to prescribe.

Urinalysis Section- Urine is tested in this section to detect disorders and infections of the kidney, urinary tract, drug abuse and metabolic diseases. Pregnancy tests are also run in this section. If you are asked to collect urine specimens from a patient, be sure to learn the proper collection method needed for the specific test.

RETURN TO THE GOOGLE CLASSROOM AND DO THE PRACTICE WORKSHEET.

Once you have completed reading and studying Module 2, and have completed Section 5-7 Practice Worksheets

RETURN TO THE GOOGLE CLASSROOM

and complete the MODULE 2 QUIZ.

(You may wait to take this quiz until after we go over Module 2 in class).

For more information and references on the reading material found in Section 7: Specimen Handling and Laboratory Processing, click the link below. Test questions will be based on the reading in the sections and not from more information found in external references and website links.

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