NHI Phlebotomy and Lab Procedures Questions and Answers — Questions and Answers
Question 1: A phlebotomist is performing a venipuncture when the patient suddenly complains of a sharp, radiating, 'electric-like' pain down their arm. Which of the following is the most appropriate immediate action?
- Reassure the patient and continue the draw slowly.
- Immediately withdraw the needle and apply pressure. (Correct answer)
- Adjust the angle of the needle to find a less painful position.
- Finish the draw as quickly as possible to minimize discomfort.
Correct answer: Immediately withdraw the needle and apply pressure.
A sharp, radiating, or 'electric-like' pain is a strong indicator of nerve involvement or injury. The standard of care requires the phlebotomist to immediately stop the procedure by withdrawing the needle to prevent further potential damage to the nerve.
Question 2: Which of the following anticoagulants is contained in a lavender-topped tube and is primarily used for hematology tests like a Complete Blood Count (CBC) because it effectively preserves the morphology of blood cells?
- Sodium Citrate
- Heparin
- Ethylenediaminetetraacetic acid (EDTA) (Correct answer)
- Sodium Fluoride
Correct answer: Ethylenediaminetetraacetic acid (EDTA)
Lavender-topped tubes contain Ethylenediaminetetraacetic acid (EDTA), which works by binding to calcium ions to prevent coagulation. It is the preferred anticoagulant for hematology studies because it does an excellent job of preserving the shape and structure of red blood cells, white blood cells, and platelets for accurate analysis.
Question 3: A phlebotomist is asked to draw blood from a patient with an active IV infusion in the left arm and a history of a mastectomy on the right side. Which of the following is the most appropriate venipuncture site?
- The right arm, as it has been several years since the mastectomy.
- The left arm, at a site above the IV cannula.
- A vein in the left hand, distal to the IV site. (Correct answer)
- The basilic vein of the right arm to avoid the primary surgical area.
Correct answer: A vein in the left hand, distal to the IV site.
Venipuncture should never be performed on the arm adjacent to a mastectomy due to the risk of lymphedema and altered test results. Drawing above an IV line is incorrect as the sample will be contaminated with IV fluid. The correct procedure is to draw from a site distal to (below) the IV, ideally after the infusion has been paused by a nurse. Therefore, the left hand is the most appropriate available site.
Question 4: During a capillary puncture on an adult's finger, which of the following actions is a critical step in ensuring the quality of the specimen?
- Making the puncture on the very tip of the finger.
- Squeezing the finger vigorously to obtain the sample quickly.
- Wiping away the first drop of blood with sterile gauze. (Correct answer)
- Puncturing parallel to the grooves of the fingerprint.
Correct answer: Wiping away the first drop of blood with sterile gauze.
The first drop of blood that appears after a capillary puncture is contaminated with interstitial fluid (tissue fluid) and potentially alcohol residue from cleaning. Wiping it away ensures that the collected specimen is composed of pure capillary blood, leading to more accurate test results.
Question 5: A physician orders a blood culture to investigate a patient for sepsis. The collected specimen, which uses special media bottles, should be delivered to which laboratory department for analysis?
- Hematology
- Chemistry
- Coagulation
- Microbiology (Correct answer)
Correct answer: Microbiology
The Microbiology department is responsible for processing specimens to detect the presence of microorganisms, such as bacteria and fungi. Blood cultures are specifically designed to grow (culture) these organisms from a blood sample to identify the cause of a systemic infection like sepsis.
Question 6: Which of the following procedural errors is a common cause of hemolysis, the rupture of red blood cells in a blood specimen?
- Inverting a tube with an additive 8-10 times.
- Using a needle with a gauge that is too small for the venipuncture. (Correct answer)
- Allowing the venipuncture site to air-dry completely after cleaning.
- Drawing tubes in the correct order.
Correct answer: Using a needle with a gauge that is too small for the venipuncture.
Using a needle with too small of a bore (e.g., a 23G or 25G needle for a large vacuum tube) can cause red blood cells to be damaged or ruptured as they are forced through the narrow opening under high pressure. This process, known as hemolysis, releases hemoglobin into the plasma or serum and can significantly alter test results.
