A phlebotomist centrifuges a serum specimen before it has fully clotted. Which of the following is most likely to occur?
Correct Answer: A
If a serum specimen is centrifuged before it has fully clotted, fibrin strands can form in the serum. These strands can interfere with testing instruments, cause sample aspiration problems, and lead to inaccurate results or specimen rejection. Serum specimens must be allowed to clot for the required time before centrifugation. Centrifugation does not increase specimen volume, neutralize additives, or sterilize blood. Blood specimens remain potentially infectious regardless of processing. This question tests the difference between serum and plasma. Serum is the liquid portion after clotting; plasma is the liquid portion of anticoagulated blood. If the phlebotomist rushes serum processing, the specimen may look separated but still contain fibrin. The correct workflow includes observing required clot time, balancing centrifuge tubes, using the correct speed and duration, and removing specimens promptly after centrifugation when required. Speed is not quality; specimen integrity is quality. Reference topics: Processing Specimens; clotting time; serum processing; centrifugation; fibrin formation.
Question 7
Which of the following tube colors is commonly used for coagulation testing?
Correct Answer: A
Light-blue tubes are commonly used for coagulation testing because they contain sodium citrate. Citrate binds calcium reversibly, preventing clotting while preserving the specimen for coagulation analysis such as PT, INR, and aPTT. The tube must be filled to the required level because coagulation testing depends on a precise blood-to-anticoagulant ratio. Underfilling a light-blue tube can falsely prolong clotting results and cause specimen rejection. Lavender tubes contain EDTA and are commonly used for hematology tests such as CBC. Gray tubes often contain sodium fluoride and potassium oxalate and are used for glucose or lactate testing depending on facility protocol. Red tubes are generally serum tubes without anticoagulant or with clot activator depending on manufacturer. The phlebotomist must collect light-blue tubes in the correct order of draw and inspect for proper fill. This is a high-yield NHA-style concept because it combines tube color, additive, test department, and specimen acceptability. Reference topics: Routine Blood Collections; coagulation tubes; sodium citrate; fill volume; order of draw.
Question 8
Which of the following PPE should a phlebotomist wear when there is a risk of blood splatter during collection?
Correct Answer: B
When there is a risk of blood splatter, the phlebotomist should wear eye and face protection, such as a face shield or goggles with a mask. Standard gloves protect the hands but do not protect the mucous membranes of the eyes, nose, and mouth. Sterile gloves are not routinely required for standard venipuncture; clean gloves are typically used unless a sterile procedure is specified. Shoe covers are not the primary protection for facial splash exposure. An N95 respirator protects against airborne particles but does not replace splash protection unless combined with appropriate eye and face protection when needed. The correct PPE is based on anticipated exposure. A routine venipuncture may require gloves only, but procedures with splash risk require additional barriers. The phlebotomist must evaluate the procedure, patient behavior, specimen type, and environment before collection. PPE use also includes proper donning, removal, disposal, and hand hygiene after glove removal. Reference topics: Safety and Compliance; PPE selection; standard precautions; splash exposure; mucous membrane protection.
Question 9
Which of the following is the purpose of centrifuging a blood specimen?
Correct Answer: B
The purpose of centrifuging a blood specimen is to separate specimen components. Centrifugation uses force to separate cells from serum or plasma based on density. In serum separator tubes, centrifugation separates serum from the clot after the specimen has fully clotted. In plasma separator tubes, centrifugation separates plasma from blood cells in the presence of anticoagulant. It does not disinfect the specimen; blood specimens must still be treated as potentially infectious. It does not activate tube additives; additives function through mixing by gentle inversion after collection. It also does not increase specimen volume. Improper centrifugation can damage specimens. Centrifuging too soon, too long, too fast, or at the wrong temperature can cause hemolysis, fibrin formation, poor separation, or analyte instability. The phlebotomist must follow manufacturer and facility instructions for clotting time, centrifuge speed, duration, balancing, and specimen removal. Reference topics: Processing Specimens; centrifugation; serum and plasma separation; specimen integrity; equipment operation.
Question 10
A phlebotomist is preparing to perform venipuncture on a patient who has had a right-sided mastectomy. Which of the following collection sites should the phlebotomist select?
Correct Answer: A
The phlebotomist should select the left antecubital area because the patient has had a right-sided mastectomy. Venipuncture should generally be avoided on the side of a mastectomy due to the risk of impaired lymphatic drainage, lymphedema, infection, and delayed healing. The right cephalic and right basilic veins are on the affected side and should not be used unless a provider specifically authorizes collection from that side. The left femoral artery is not an appropriate routine phlebotomy site and arterial collection is outside standard venipuncture practice unless performed under specialized authorization and scope. The left antecubital area is the safest option listed because it uses the unaffected arm and provides standard venipuncture access. The technician should still assess vein suitability, avoid sites with IVs, edema, scarring, hematoma, or infection, and follow facility policy if no acceptable site is available. This question tests contraindicated sites and safe site selection, not simply vein-name recall. Reference topics: Routine Blood Collections; mastectomy precautions; venipuncture site selection; contraindicated sites; patient safety.
