MLPAO - Medical Laboratory Professionals Association of Ontario Specimen Collection and Handling Questions and Answers — Questions and Answers
Question 1: An MLA/T is tasked with collecting blood for coagulation studies (light blue top), a complete blood count (lavender top), and a basic metabolic panel (serum separator tube - SST). To prevent additive cross-contamination, what is the correct order of draw?
- Lavender top, SST, Light blue top
- Light blue top, SST, Lavender top (Correct answer)
- SST, Lavender top, Light blue top
- Light blue top, Lavender top, SST
Correct answer: Light blue top, SST, Lavender top
The correct order of draw is based on CLSI guidelines to prevent contamination of specimens by additives from other tubes. The sequence is: 1) Blood cultures, 2) Sodium Citrate (light blue top) for coagulation, 3) Serum tubes with or without clot activator/gel (SST), 4) Heparin (green top), 5) EDTA (lavender top), and 6) Glycolytic inhibitor (gray top). Following this order ensures that the citrate tube for coagulation is drawn before tubes with clot activators or other additives that could interfere with testing.
Question 2: A physician's office sends a urine specimen for culture and sensitivity to the laboratory. Upon receipt, the MLA/T notices the specimen is in a non-sterile container. What is the most appropriate action?
- Process the specimen and add a comment about the container.
- Transfer the urine to a sterile container and proceed with testing.
- Reject the specimen and request a new sample collected in the proper container. (Correct answer)
- Aliquot a small amount for culture and discard the rest.
Correct answer: Reject the specimen and request a new sample collected in the proper container.
Microbiology specimens for culture must be collected in sterile containers to prevent the introduction of environmental bacteria, which would lead to inaccurate results. A non-sterile container compromises the specimen's integrity, making it unacceptable for culture. The proper procedure is to reject the specimen and notify the provider to collect a new, valid sample.
Question 3: Which of the following analytes requires the specimen to be protected from light during collection and transport?
- Glucose
- Potassium
- Bilirubin (Correct answer)
- Creatinine
Correct answer: Bilirubin
Bilirubin is a light-sensitive analyte. Exposure to light, especially UV and fluorescent light, causes it to degrade rapidly, leading to falsely low results. Therefore, specimens for bilirubin testing must be collected in amber-colored tubes or wrapped in foil to protect them from light.
Question 4: An MLA/T receives a blood specimen for a Prothrombin Time (PT) test in a light blue top tube. The MLA/T observes that the tube is only filled to 50% of its capacity. What is the implication of this short draw?
- The results will be falsely shortened (lower).
- The results will be falsely prolonged (higher). (Correct answer)
- The specimen will likely be hemolyzed.
- There is no significant impact on the test results.
Correct answer: The results will be falsely prolonged (higher).
Light blue (sodium citrate) tubes used for coagulation testing require a specific 9:1 blood-to-anticoagulant ratio. An underfilled tube contains an excess of the citrate anticoagulant relative to the amount of blood, which will bind more calcium than necessary and lead to falsely prolonged clotting times for tests like PT and aPTT.
Question 5: When collecting a specimen for forensic toxicology testing, what is the most critical procedure that must be meticulously followed to ensure the specimen is admissible in legal proceedings?
- Using a gray-top tube for collection.
- Placing the specimen on ice immediately.
- Maintaining a strict chain of custody. (Correct answer)
- Obtaining a fasting sample from the donor.
Correct answer: Maintaining a strict chain of custody.
Chain of custody is the chronological documentation or paper trail, showing the seizure, custody, control, transfer, analysis, and disposition of physical or electronic evidence. For forensic and legal testing, a meticulously maintained chain of custody is essential to prove that the specimen has not been tampered with and to ensure its integrity from collection to reporting.
Question 6: According to Ontario laboratory guidelines, which two identifiers are the minimum requirement for labeling a primary patient specimen at the time of collection?
- Patient's full name and room number.
- Patient's date of birth and the date of collection.
- Patient's full name and one other unique identifier (e.g., DOB or Health Card Number). (Correct answer)
- Patient's Health Card Number and the physician's name.
Correct answer: Patient's full name and one other unique identifier (e.g., DOB or Health Card Number).
Ontario guidelines mandate that, at the time of collection, all specimens must be labeled with at least two unique patient identifiers. These must include the patient's full surname and first name, plus one other unique identifier such as their date of birth (DOB) or Health Card Number. This is a critical step to prevent pre-analytical errors and ensure patient safety.
MLPAO - Medical Laboratory Professionals Association of Ontario Specimen Collection and Handling Questions and Answers
An MLA/T is tasked with collecting blood for coagulation studies (light blue top), a complete blood count (lavender top), and a basic metabolic panel (serum separator tube - SST).
To prevent additive cross-contamination, what is the correct order of draw?