- A phlebotomist is collecting specimens for multiple patients in the emergency department. For a patient requiring STAT glucose, electrolytes, cardiac enzymes, and a type and crossmatch, which represents the correct order of draw considering both routine protocols and STAT requirements?
Answer: Gold SST tube first for STAT glucose and chemistry, then pink EDTA for crossmatch
While order of draw is important, STAT orders take priority for patient care. The chemistry tests (glucose, electrolytes, cardiac enzymes) requiring the gold SST tube should be drawn first to expedite critical results. The type and crossmatch in the pink EDTA tube, while important, is typically less time-sensitive than STAT chemistry values. No coagulation studies are ordered, so no citrate tube is needed.
- A phlebotomist needs to collect blood for prothrombin time, partial thromboplastin time, fibrinogen, and complete blood count using a 21-gauge straight needle with evacuated tubes. The first light blue tube fails to fill completely due to equipment malfunction. What is the correct procedure to ensure accurate coagulation testing?
Answer: Remove the needle, apply new equipment, and restart the draw with a fresh light blue tube first
Coagulation tests require precise blood-to-anticoagulant ratios for accurate results. A partially filled tube will yield unreliable PT, PTT, and fibrinogen values. The equipment must be changed and the draw restarted with coagulation tubes first, following proper order of draw. Drawing CBC first would compromise the order of draw for the subsequent coagulation collection, and using a partially filled tube would provide inaccurate results.
- When performing a difficult draw on an elderly patient with fragile veins, a phlebotomist successfully collects blood for ESR, glucose, and potassium using a 23-gauge butterfly needle. However, the vacuum in the light blue tube appears weak and the tube fills slowly. What is the most appropriate action to ensure accurate test results?
Answer: Redraw the light blue tube first using a new venipuncture site and fresh equipment
ESR requires proper blood-to-anticoagulant ratio in the citrate tube for accurate results. A partially filled tube will have incorrect ratios, leading to unreliable ESR values. The tube must be redrawn with a new venipuncture to ensure proper fill. Using a smaller tube won't solve the vacuum issue, transferring from another tube violates order of draw principles, and using a partially filled tube compromises test accuracy.
- During a routine venipuncture, a phlebotomist draws a royal blue trace element tube for copper level, followed by a lavender EDTA tube for CBC, then a gold SST tube for comprehensive metabolic panel. What error has occurred and what is the most likely impact on test results?
Answer: The royal blue tube should be drawn last to prevent trace metal contamination affecting the CBC results
Royal blue tubes for trace elements should be drawn last in the order to prevent contamination of subsequent tubes with trace metals from the needle. Drawing it first could contaminate the lavender and gold tubes, potentially affecting CBC and chemistry results. The order should be: lavender (EDTA), gold (SST), then royal blue (trace elements). Trace element tubes are specifically designed to be drawn last to prevent cross-contamination.
- A syringe draw includes a CBC and PT/INR. Which fill order is correct?
Answer: Light blue, then lavender
Collect the light blue citrate tube first because EDTA from a lavender tube contaminates the sample and alters PT/INR results. Choosing lavender first is tempting for the CBC, but it would ruin the coagulation testing. Fill order is not optional.
- During a home health visit, a phlebotomist needs to collect blood for warfarin monitoring (PT/INR), hemoglobin level, and liver function tests. Due to the patient's difficult venous access, only one successful venipuncture is possible. The phlebotomist uses a syringe and transfers blood to tubes. What is the critical consideration for accurate PT/INR results in this scenario?
Answer: Transfer a small amount to a discard tube first, then fill the light blue tube to proper level
When using a syringe system, tissue thromboplastin and air in the syringe can contaminate the first specimen transferred, leading to falsely elevated PT/INR results. A discard volume must be transferred first to clear contamination before filling the light blue tube to the proper fill level (not completely full). The order after discard is: light blue, lavender, then gold. Overfilling or mixing the syringe would not address the contamination issue.
- A red top and an SST are ordered, with no light blue. Which first?
Answer: Red top before SST
Red top has no additives, so you draw it before the SST, which contains clot activator and gel. The additive-free tube is always collected first to prevent clot activators from contaminating it. The tempting error is putting SST before red because both collect serum, but the SST's additives place it after the red top.
- In an outpatient setting, a phlebotomist must collect specimens for therapeutic drug monitoring (lithium level), routine chemistry panel, and platelet count. The laboratory protocol specifies that lithium levels require a green lithium heparin tube. What modification to the standard order of draw is necessary?
Answer: Draw a separate green tube without lithium heparin for the lithium level testing
Lithium levels cannot be collected in lithium heparin tubes due to contamination from the additive itself. A green tube with sodium heparin or a royal blue tube with alternative anticoagulant must be used instead. The standard green lithium heparin tube would falsely elevate lithium results. The order would be: alternative green/royal blue tube for lithium, lavender for platelets, then gold for other chemistry tests.
- A phlebotomist is training a new employee on order of draw principles. When collecting blood for activated clotting time (ACT), basic metabolic panel, and white blood cell count, the trainer notices the new employee draws the tubes in this sequence: gold SST, lavender EDTA, then gray sodium fluoride. What correction should be made?
Answer: A light blue citrate tube should be added first for the ACT, before all other tubes
When you encounter questions about blood draw sequences, you must immediately think about the standard order of draw, which prevents cross-contamination between different tube additives. The key here is recognizing that activated clotting time (ACT) is a coagulation study requiring a citrate tube.
The correct sequence requires adding a light blue sodium citrate tube first for the ACT test. Coagulation studies like ACT, PT, and PTT always require citrate tubes, which contain sodium citrate to chelate calcium and prevent clotting during transport. In the standard order of draw, citrate tubes come second (after blood culture bottles), but since no blood cultures are mentioned here, the citrate tube should be drawn first.
Looking at the wrong answers: Choice A incorrectly prioritizes glucose preservation over preventing cross-contamination - while glucose does degrade over time, the gray tube's position in this sequence isn't the primary concern. Choice B misunderstands contamination flow - EDTA contamination is actually prevented by drawing the lavender tube after chemistry tubes, not before. Choice D completely misses that ACT is a coagulation study, despite not being explicitly labeled as such.
The employee's sequence (gold SST, lavender EDTA, gray sodium fluoride) follows proper order for those three tubes but omits the essential citrate tube needed for ACT testing.
Study tip: Memorize common coagulation tests beyond just "PT/PTT" - ACT, bleeding time, and D-dimer all require specific collection methods. When you see any coagulation test mentioned, immediately think "citrate tube" and proper order of draw positioning.
- A patient requires blood draws for troponin, D-dimer, hemoglobin A1C, and magnesium level. The phlebotomist has collected blood in a gold SST tube and a lavender EDTA tube. Upon reviewing the test requirements, which additional tube must be collected and in what position relative to the already drawn tubes?
Answer: Light blue citrate tube, which should have been drawn before both existing tubes
D-dimer requires a light blue citrate tube for coagulation testing. According to order of draw, citrate tubes must be collected before both EDTA (lavender) and clot activator tubes (gold SST). The troponin and magnesium can be run on the SST tube, and HbA1C on the EDTA tube. The phlebotomist will need to recollect following proper order: light blue first, then lavender, then gold.
- During a venipuncture using a butterfly needle and syringe system, a phlebotomist needs to collect specimens for PT/INR, CBC, and basic metabolic panel. What is the most critical step to ensure accurate coagulation results when transferring blood from the syringe to the collection tubes?
Answer: Fill a discard tube first, then light blue, lavender, and gold top tubes
When using a syringe system, a discard tube must be filled first before the coagulation tube to clear air and tissue thromboplastin from the needle and syringe. This prevents contamination that could falsely elevate PT/INR results. The order then follows: discard, light blue (coagulation), lavender (hematology), gold (chemistry). Without the discard tube, coagulation results would be unreliable.
- A phlebotomist is drawing blood for the following tests: CBC, comprehensive metabolic panel, PT/INR, blood culture, and glucose. After collecting the blood culture first, which tube should be drawn second to prevent contamination from carryover additives while maintaining proper coagulation testing integrity?
Answer: Light blue top tube (sodium citrate) for PT/INR testing
After blood culture, the light blue top tube for coagulation studies (PT/INR) should be drawn second. This follows the standard order of draw: blood culture, coagulation (light blue), then other tubes. Drawing the coagulation tube early prevents contamination from other additives that could affect clotting times. A discard tube is not needed when using an evacuated tube system. EDTA and SST tubes come later in the order.
- Which order is correct for blood culture, green, and gray tubes?
Answer: Culture, green, gray
Blood cultures always go first to avoid contamination. Among anticoagulant tubes, green (heparin) precedes gray (sodium fluoride/potassium oxalate) because gray additives can contaminate other tubes if drawn earlier. The common error is putting gray before green, but gray belongs near the end of the draw order.
- A winged set is used for only a light-blue tube. What is drawn first?
Answer: Nonadditive discard tube
The winged set tubing contains air, so when only a light-blue coagulation tube is collected, the dead space must be filled with a nonadditive discard tube before the light-blue tube. A lavender tube has additive and cannot serve as discard; saying no discard is wrong because the air in the tubing would compromise the coagulation sample.
- After drawing SST, lavender, then light blue, which specimen is invalid?
Answer: PT/INR specimen
The lavender tube contains EDTA, which chelates calcium and contaminates a light blue tube drawn after it. Since PT/INR testing depends on calcium in the coagulation cascade, that light blue specimen is invalid. The SST CMP and lavender CBC are still valid for their own tests. The tempting wrong answer is all three, but only the coagulation tube is ruined by the EDTA carryover.
