Blood Cultures
What is the primary clinical reason a blood culture is ordered?
Detect suspected bacterial or fungal bloodstream infection (sepsis).
Which color tube is used for glucose testing and why?
Gray‑topped tubes; sodium fluoride prevents glycolysis.
What is the name of the intoxicating substance measured in blood alcohol testing?
Ethanol (EtOH).
What condition is universally screened for in U.S. newborn metabolic screening programs and why?
Phenylketonuria (PKU) — to prevent brain damage via early detection and treatment.
For urine drug testing, name one identification and one chain‑of‑custody step often required at collection.
Photo ID verification;
collector completes documentation and seals specimen in front of patient (chain‑of‑custody).
Name two general rules a phlebotomy technician must follow before performing a point‑of‑care test.
Follow facility patient ID and infection control procedures; only operate devices they are trained on.
Name the two types of bottles used for blood culture collection and the main difference between them.
For a glucose challenge test (one‑hour), does the patient need to fast? When is the blood drawn?
Why might facilities instruct phlebotomists to use a non‑alcohol antiseptic for site cleaning before blood alcohol collection?
To avoid potential contamination of the sample with alcohol from antiseptic; many facilities require non‑alcohol antiseptic despite mixed evidence.
Describe how blood is collected onto the filter paper for newborn metabolic screening (what must not touch the paper and how should each circle appear).
Blood is allowed to drip onto the front side of filter paper; do not touch paper to baby’s foot; each circle must be fully covered and soaked through.
When collecting a split urine specimen, what minimum volumes are typically required for the primary and secondary containers?
Typically at least 30 mL in primary container and 15 mL in secondary (split) container (may vary by program).
Why is it important to check expiration dates and storage conditions for test strips or cartridges used in point‑of‑care testing?
Expired or improperly stored strips give invalid results; storage affects reagent stability and accuracy.
Describe two key antiseptic steps that reduce contamination risk when collecting blood cultures.
Outline the main difference in specimen timing between a glucose challenge test and a glucose tolerance test.
Challenge: single post‑drink draw (often 1 hour) and no fasting;
Tolerance: fasting baseline draw then multiple timed draws (1, 2, 3 hours).
Define “chain of custody” in the context of blood alcohol testing and give one reason it is required.
Chain of custody documents the specimen’s path from collection to analysis to ensure integrity and admissibility in court.
Explain why only one drop is placed in each circle of the newborn screening card and why soaking through front and back is required.
One drop prevents over‑saturation and mixing; soaking through ensures enough sample for analysis and that both sides contain blood for lab processing.
Describe two measures taken at collection sites to reduce the chance of specimen tampering during urine drug collection.
Turn off/block water,
add coloring to toilet,
observe collection,
inspect patient pockets,
temperature check immediately after collection.
If a point‑of‑care test produces a critical value, what immediate actions must the PBT take according to the guidelines
Report immediately to supervisor/physician, repeat test to confirm (if required), document, and follow facility critical result reporting protocol.
— Explain why a winged collection set (butterfly) is recommended for blood culture draws.
Prevents broth backflow into patient, keeps bottles upright while filling, and allows clear visualization of fill level.
A glucose tolerance test requires multiple timed draws. Explain why strict adherence to the draw schedule and documentation is important for diagnostic accuracy.
Timing affects measured glucose concentrations and diagnostic interpretation; deviations can cause false negatives/positives.
Some states have implied consent laws for blood alcohol testing. Explain what “implied consent” means in this context and one practical implication for specimen collection.
Implied consent: by holding a driver’s license, a person may implicitly agree to testing; practically, specimens can sometimes be drawn without explicit signed consent (varies by law).
A newborn metabolic screen form must be fully completed before sending. List three critical pieces of information that should be on the form.
Patient/infant identifiers (name, DOB), collection date/time, newborn age in hours/days at collection, collector ID, and screening site ID.
For a 24‑hour urine collection, explain the patient’s first‑morning action to begin the collection and how the total volume should be handled/documented.
Void first morning into toilet (not collected) to start 24‑hour period; collect all urine for 24 hours, document start/end time and total volume before aliquot or testing.
Explain why PBTs must not discuss diagnoses or treatment with patients and how test results should be communicated instead.
PBTs are not licensed to diagnose; they must report results to ordering provider and document per facility protocol.
A facility allows either direct fill into culture bottles or syringe transfer. Discuss the infection‑control reason the guideline prefers collecting directly into culture bottles when allowed.
Each transfer increases contamination risk; direct collection minimizes handling and transfer steps.
Describe how the sodium fluoride additive in gray‑topped tubes helps preserve a valid glucose result and name the biochemical process it prevents.
Sodium fluoride inhibits enolase and other glycolytic enzymes, preventing cellular metabolism of glucose (glycolysis).
Describe two documentation or procedural steps a phlebotomy technician must follow if drawing a blood specimen for legal purposes (e.g., DUI) beyond routine labeling.
Use non‑alcohol antiseptic per policy,
document exact collection time,
witness signatures,
seals, transport logs, and complete chain‑of‑custody paperwork.
Discuss why timing of newborn screening (e.g., age of the infant at collection) matters and how improper timing can affect detection of metabolic disorders.
Many metabolic markers change after feeding or with age; early or late collection may yield false negatives or require repeat testing.
For fecal occult blood testing (guaiac), list three dietary or medication items patients are often asked to avoid before testing and explain why avoidance matters.
Red meat, raw fruits/vegetables/horseradish, vitamin C, aspirin/NSAIDs — these can cause false positives/negatives or chemical interference.
Describe the steps a PBT should follow to perform quality control on a point‑of‑care device and explain why regular QC matters for patient safety and result reliability.
Run manufacturer recommended controls at specified intervals, log control results, troubleshoot and remove device from service if QC fails; QC ensures accuracy and patient safety.