Phlebotomy Medical Dictionary
MLT 410 & 411 – Weeks 4-5
A
Airborne Precautions
Definition: Infection control measures used to prevent transmission of pathogens that remain infectious over long distances when suspended in the air (droplet nuclei smaller than 5 microns).
In Context: When drawing blood from a patient with tuberculosis, the phlebotomist must follow airborne precautions, including wearing an N95 respirator mask and ensuring the patient is in a negative pressure room.
Anticoagulant
Definition: A substance that prevents blood from clotting by interfering with the coagulation cascade.
In Context: The phlebotomist selected a lavender-top tube containing EDTA anticoagulant for the complete blood count, as this prevents clotting while preserving cell morphology.
B
Biohazard
Definition: Any biological substance that poses a threat to human health, including blood, body fluids, tissues, and materials contaminated with potentially infectious agents.
In Context: All used needles and blood-contaminated materials must be disposed of in the red biohazard sharps container to prevent accidental exposure and disease transmission.
Blood Cultures
Definition: Laboratory tests performed on blood samples to detect the presence of bacteria, fungi, or other microorganisms in the bloodstream (septicemia or bacteremia).
In Context: Blood cultures are always drawn first in the order of draw to minimize contamination risk, using sterile technique and yellow-top ACD tubes.
C
CLIA (Clinical Laboratory Improvement Amendments)
Definition: Federal regulatory standards that apply to all clinical laboratory testing performed on humans in the United States, ensuring quality, accuracy, and reliability.
In Context: Our laboratory maintains strict CLIA compliance by following all regulations for personnel qualifications, quality control, and proficiency testing.
Coagulated
Definition: The state of blood that has clotted, forming a gel-like mass due to the conversion of fibrinogen to fibrin.
In Context: The specimen was rejected because the blood had coagulated in the tube, making it unsuitable for testing that requires liquid serum or plasma.
Contact Precautions
Definition: Infection control measures used to prevent transmission of pathogens spread by direct or indirect contact with the patient or their environment.
In Context: When drawing blood from a patient with MRSA, the phlebotomist must implement contact precautions by wearing gloves and a gown before entering the room.
D
DOB (Date of Birth)
Definition: The calendar date on which a patient was born, used as a critical identifier in patient identification.
In Context: Before performing the venipuncture, the phlebotomist verified the patient’s identity by asking them to state their full name and date of birth.
Droplet Precautions
Definition: Infection control measures used to prevent transmission of pathogens spread through large respiratory droplets (larger than 5 microns) generated during coughing, sneezing, or talking.
In Context: The phlebotomist donned a surgical mask before entering the room of a patient with influenza, following droplet precautions protocol.
E
EDTA (Ethylenediaminetetraacetic Acid)
Definition: An anticoagulant that prevents blood clotting by binding (chelating) calcium ions, commonly found in lavender-top and pink-top tubes.
In Context: EDTA tubes with lavender tops are used for hematology testing because they preserve blood cell morphology while preventing coagulation.
H
Hemolysis
Definition: The rupture or destruction of red blood cells, releasing hemoglobin into the surrounding fluid, causing serum or plasma to appear pink to red.
In Context: The specimen showed hemolysis due to the small needle gauge and excessive suction during collection, requiring the phlebotomist to redraw the sample.
Heparin
Definition: An anticoagulant that prevents blood clotting by inactivating thrombin and other clotting factors, commonly found in green-top tubes.
In Context: Green-top tubes containing heparin are used for plasma chemistry tests and stat electrolyte panels because heparin works rapidly to prevent clotting.
I
Icterus
Definition: A yellowish discoloration of serum or plasma caused by elevated bilirubin levels, also known as jaundice.
In Context: The laboratory noted icterus in the patient’s serum sample, which appeared yellow in color and indicated possible liver dysfunction or hemolytic disease.
L
Laboratory Requisition
Definition: A form or electronic order that contains essential patient information and specifies which laboratory tests should be performed on collected specimens.
In Context: The laboratory requisition included the patient’s name, medical record number, date of birth, ordering physician, and the specific tests requested.
Light Blue Top Tube
Definition: A blood collection tube containing sodium citrate anticoagulant, used primarily for coagulation studies and positioned second in the order of draw.
In Context: For the PT/INR test, the phlebotomist collected blood in a light blue top tube, ensuring it was filled to the proper level for accurate coagulation testing.
Lipemia
Definition: The presence of excess fats or lipids in the serum or plasma, giving the specimen a milky or turbid appearance.
In Context: The patient’s specimen showed lipemia because they had not fasted before the blood draw, requiring either specimen rejection or notation of the lipemic condition on the results.
M
Medical Record Number (MRN)
Definition: A unique identifier assigned to each patient within a healthcare facility’s record system, used to accurately match specimens and results to the correct patient.
In Context: Along with the patient’s name and date of birth, the phlebotomist verified the medical record number on the requisition matched the patient’s wristband before proceeding with the blood draw.
O
Order of Draw
Definition: The specific sequence in which blood collection tubes should be filled during venipuncture to prevent cross-contamination of additives between tubes.
In Context: Following the correct order of draw—starting with blood cultures, then light blue, red, gold SST, green, lavender, and finally gray—ensures accurate test results by preventing additive carryover.
P
Patient Identification
Definition: The critical first step in the phlebotomy process involving verification of the patient’s identity using at least two unique identifiers before specimen collection.
In Context: Patient identification is the phlebotomist’s most important first action, requiring verbal confirmation of the patient’s full name and date of birth, and verification against the wristband and requisition.
Phlebotomist
Definition: A healthcare professional trained to collect blood specimens from patients through venipuncture, capillary puncture, or arterial puncture for laboratory testing.
In Context: The phlebotomist is critically important in healthcare because they are responsible for proper patient identification, quality specimen collection, and accurate labeling—all essential for correct diagnosis and treatment.
Plasma
Definition: The liquid portion of blood obtained when an anticoagulant is added to prevent clotting; it contains water, proteins, electrolytes, nutrients, and clotting factors.
In Context: To obtain plasma for the chemistry panel, the phlebotomist collected blood in a green-top heparin tube and centrifuged it to separate the liquid plasma from the cellular components.
Preanalytical Errors
Definition: Mistakes that occur before laboratory analysis, including errors in patient preparation, specimen collection, handling, labeling, or transportation.
In Context: Common preanalytical errors include improper patient identification, incorrect order of draw, insufficient mixing of tubes, and delays in specimen processing—all of which can compromise test accuracy.
R
Red Top Tube
Definition: A blood collection tube without additives or with a clot activator, used to obtain serum for various chemistry and immunology tests; positioned third in the order of draw.
In Context: The phlebotomist selected a red top tube for the serology testing, allowing the blood to clot naturally before centrifugation to obtain serum.
S
Serum
Definition: The liquid portion of blood obtained after blood has clotted and the clot has been removed; it contains no clotting factors or cells.
In Context: Serum is collected in red-top or gold-top SST tubes and is used for most chemistry tests, hormone levels, and antibody detection.
SST (Serum Separator Tube)
Definition: A blood collection tube with a gold or tiger-striped top containing a clot activator and a polymer gel barrier that separates serum from cells during centrifugation.
In Context: The SST tube, positioned fourth in the order of draw, is ideal for chemistry tests because the gel barrier prevents cellular contamination of the serum after centrifugation.
Standard Precautions
Definition: Infection control practices used with all patients, regardless of diagnosis, treating all blood and body fluids as potentially infectious.
In Context: The phlebotomist applies standard precautions with every patient by wearing gloves, using hand hygiene, and handling all specimens and contaminated materials as if they were infectious.
T
Three Categories of Patient Isolation
Definition: The classification system for infection control that includes contact precautions, droplet precautions, and airborne precautions, each targeting specific transmission routes.
In Context: Understanding the three categories of patient isolation helps phlebotomists select appropriate personal protective equipment based on the patient’s infectious disease status.
Three Phases and Levels of Testing
Definition: The laboratory testing process divided into preanalytical (before testing), analytical (during testing), and postanalytical (after testing) phases, with different complexity levels defined by CLIA.
In Context: Phlebotomists work primarily in the preanalytical phase, where proper specimen collection and handling are critical to ensure accuracy in the subsequent analytical and postanalytical phases.
Thrombin
Definition: An enzyme in the coagulation cascade that converts fibrinogen to fibrin, essential for blood clot formation.
In Context: Heparin anticoagulant works by inactivating thrombin, thereby preventing the conversion of fibrinogen to fibrin and stopping the clotting process.
Thirty-Minute Rule
Definition: The recommended timeframe for delivering specimens to the laboratory after collection to ensure specimen integrity and accurate test results.
In Context: Following the thirty-minute rule, the phlebotomist immediately transported the specimens to the lab to prevent hemolysis, glycolysis, and other time-dependent changes.
U
Unacceptable Specimen Types
Definition: Blood or body fluid samples that do not meet quality standards for testing due to issues such as hemolysis, insufficient quantity, clotting, mislabeling, or improper collection.
In Context: The laboratory rejected the specimen as an unacceptable specimen type because it was collected in the wrong tube, inadequately labeled, and showed visible hemolysis.
W
Whole Blood
Definition: Blood in its natural state containing all cellular components (red blood cells, white blood cells, platelets) suspended in plasma.
In Context: Whole blood collected in EDTA tubes is used for complete blood counts, as the test requires analysis of all blood cell types in their original proportions.
Classes of Fire
Class A Fire
Definition: Fires involving ordinary combustible materials such as paper, wood, cloth, and plastic.
In Context: A Class A fire extinguisher containing water or foam should be available in the phlebotomy office area where paper requisitions and supplies are stored.
Class B Fire
Definition: Fires involving flammable liquids such as alcohol, gasoline, oil, and grease.
In Context: The phlebotomy station keeps a Class B fire extinguisher nearby because alcohol-based hand sanitizers and cleaning solutions are considered flammable liquids.
Class C Fire
Definition: Fires involving energized electrical equipment such as computers, monitors, centrifuges, and other electrical devices.
In Context: When the centrifuge began smoking, the phlebotomist used a Class C fire extinguisher because water-based extinguishers should never be used on electrical fires.
Class D Fire
Definition: Fires involving combustible metals such as magnesium, titanium, and sodium.
In Context: While Class D fires are rare in phlebotomy settings, laboratories that handle reactive metals must have specialized extinguishing agents available.
Class K Fire
Definition: Fires involving cooking oils, fats, and greases typically found in kitchen facilities.
In Context: The hospital cafeteria near the laboratory is equipped with Class K fire extinguishers specifically designed for grease fires.
Color-Coded Tube Reference
Yellow Top (Sterile)
Position: First in order of draw
Use: Blood cultures or ACD (acid citrate dextrose)
Purpose: Sterile collection to detect microorganisms in blood
Light Blue Top
Position: Second in order of draw
Additive: Sodium citrate
Use: Coagulation studies (PT, PTT, INR)
Red Top
Position: Third in order of draw
Additive: None or clot activator only
Use: Serum chemistry, immunology, serology
Gold/Tiger Top (SST)
Position: Fourth in order of draw
Additive: Clot activator and polymer gel
Use: Serum chemistry tests
Green Top
Position: Fifth in order of draw
Additive: Heparin (sodium, lithium, or ammonium)
Use: Plasma chemistry, stat tests
Lavender/Pink Top
Position: Sixth in order of draw
Additive: EDTA
Use: Hematology (CBC, blood bank)
Gray Top
Position: Seventh (last) in order of draw
Additive: Potassium oxalate/sodium fluoride
Use: Glucose testing, alcohol levels
Study Tip: Remember the order of draw with the mnemonic:
“Blood Lovers Like Red Gold Lights Gray”
(Blood cultures, Light blue, Red, Gold, Lights/Lavender, Gray)
End of Dictionary
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