MLAB 147 Unit 2: Preanalytical Variables & Complications
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146 Terms
Q:* What are preanalytical variables?
A: Factors that occur before testing that can affect specimen results.
Q: What are the three phases of laboratory testing?
A: Preanalytical, analytical, and postanalytical phases.
Q: Which phase contains most laboratory errors?
A: The preanalytical phase.
Q: What does the preanalytical phase include?
A: Patient preparation, collection, handling, and transport of specimens.
Q: What is basal state?
A: The patient’s standard condition after 12 hours of fasting and no exercise.
Q: What are the requirements for basal state?
A: 12 hours fasting, resting, and no exercise.
Q: Why is basal state important?
A: It provides standardized conditions for accurate results.
Q: What are the key patient variables affecting laboratory results?
A: Fasting, posture, medications, exercise, and altitude.
Q: How does fasting affect laboratory testing?
A: It reduces variation caused by food intake.
Q: How does exercise affect laboratory results?
A: It can change analyte levels due to muscle activity and fluid shifts.
Q: Why should patients avoid exercise before certain tests?
A: Exercise can alter laboratory values and affect accuracy.
Q: How does posture affect laboratory results?
A: Changing position shifts body fluids and can change concentration of some analytes.
Q: Which analytes can be affected by posture?
A: Proteins, lipids, calcium, and albumin.
Q: How can medications affect laboratory results?
A: They can increase, decrease, or interfere with analyte measurements.
Q: How can altitude affect laboratory results?
A: It can change certain blood values due to oxygen availability changes.
Q: What should you do if a patient is missing for a timed draw?
A: Document the delay, notify the nurse/physician, and reschedule.
Q: Why are timed draws important?
A: The accuracy depends on collecting at the correct time.
Q: What is the correct action for a missing timed
draw patient?
Q: What is iatrogenic anemia?
A: Anemia caused by excessive blood loss from medical procedures.
Q: What can cause iatrogenic anemia in hospitalized patients?
A: Excessive blood collection.
Q: What is the most important goal of patient preparation?
A: Obtaining accurate and reliable results.
Q: What is the first consideration when selecting a venipuncture site?
A: Patient safety and specimen quality.
Q: Which side should be avoided after a mastectomy?
A: The same side as the mastectomy.
Q: Why should blood not be collected from the mastectomy side?
A: Risk of lymphostasis and lymphedema.
Q: What is lymphostasis?
A: Impaired movement of lymph fluid.
Q: What is lymphedema?
A: Swelling caused by accumulation of lymph fluid.
Q: What is required before drawing from a mastectomy side?
A: Physician permission.
Q: What are sclerosed veins?
A: Hard, thickened veins that feel cord
Q: How do sclerosed veins feel during palpation?
A: Hard, cord
Q: Why should sclerosed veins be avoided?
A: They have poor blood flow and increased infection risk.
Q: What is a hematoma?
A: A collection of blood under the skin caused by leakage from a vessel.
Q: What does a hematoma look like?
A: Swelling caused by trapped blood.
Q: What is the first action if a hematoma forms during collection?
A: Stop the draw, remove the tourniquet, remove the needle, and apply pressure.
Q: What is the STOP protocol for hematomas?
A: Strip tourniquet off, Take needle out, Observe/apply Pressure, document.
Q: What causes a hematoma during venipuncture?
A: Excessive probing, leaving tourniquet on during needle withdrawal, or puncturing through both sides of the vein.
Q: Does applying pressure with the arm straight cause a hematoma?
A: No, it helps prevent hematoma formation.
Q: What is edematous tissue?
A: Tissue swollen with excess fluid.
Q: Why should edematous areas be avoided?
A: They can dilute the specimen and affect results.
Q: What is the main concern with drawing from swollen tissue?
A: Sample dilution.
Q: What is hemolysis?
A: The rupture or breakdown of red blood cells.
Q: Why is hemolysis a problem in laboratory testing?
A: It can alter test results and make specimens inaccurate.
Q: What substance is released when RBCs hemolyze?
A: Intracellular contents such as potassium.
Q: Which chemistry test is most affected by hemolysis?
A: Potassium (K⁺).
Q: Why is potassium highly affected by hemolysis?
A: RBCs contain high potassium concentrations that are released when they rupture.
Q: Which liver/muscle enzymes are affected by hemolysis?
A: AST and LDH.
Q: Which coagulation test can be affected by hemolysis?
A: PTT.
Q: What is a major prevention method for hemolysis during difficult draws?
A: Use a winged infusion set (butterfly).
Q: Why is a butterfly needle useful for difficult draws?
A: It reduces trauma to RBCs and helps prevent hemolysis.
Q: What are common causes of hemolysis?
A: Difficult collection, excessive force, improper handling, and traumatic draws.
Q: What is lipemia?
A: A cloudy or milky appearance of serum/plasma caused by increased fats.
Q: What causes lipemia?
A: High triglycerides, cholesterol, or recent food intake.
Q: What does lipemic plasma look like?
A: Milky or cloudy.
Q: What is the lipemia memory trick?
A: Lipemia = Latte (milky appearance).
Q: What is icterus?
A: A dark yellow or brown plasma appearance caused by high bilirubin.
Q: What causes icterus?
A: Increased bilirubin levels, often related to liver issues.
Q: What does icteric plasma look like?
A: Dark yellow, amber, or brown.
Q: What is the icterus memory trick?
A: Icterus = Intense Gold (bilirubin).
Q: What are the three LIH specimen appearance changes?
A: Lipemia, Icterus, and Hemolysis.
Q: What does LIH stand for?
A: Lipemia, Icterus, Hemolysis.
Q: What is the hemolysis memory trick?
A: Hemolysis = Hot Red (cherry
Q: What colour is a hemolyzed specimen?
A: Pink to red because of free hemoglobin.
Q: What antiseptic should not be used for dermal punctures?
A: Povidone iodine.
Q: Why should povidone iodine be avoided for dermal punctures?
A: It can interfere with certain test results.
Q: Which tests are affected by povidone iodine contamination?
A: Bilirubin, uric acid, and phosphorus.
Q: What should be used instead of povidone iodine?
A: Isopropyl alcohol or chlorhexidine according to protocol.
Q: Why is specimen contamination from antiseptics a concern?
A: It can create inaccurate laboratory results.
Q: What does arterial blood look like?
A: Bright red and oxygen
Q: How can you recognize an arterial puncture?
A: Bright red blood that pulses or spurts.
Q: What is the action if an arterial puncture occurs?
A: Apply extra pressure.
Q: Why is extra pressure needed after arterial puncture?
A: Arteries have higher pressure and bleed more.
Q: What is the ABC emergency memory trick?
A: Arterial = Bright & Color (red) = Abort draw.
Q: What is the maximum temperature for capillary warming?
A: 42°C.
Q: Why is capillary warming performed?
A: To increase blood flow for easier collection.
Q: What is the maximum safe capillary warming temperature?
A: 42 degrees Celsius.
Q: What are common reasons for specimen rejection?
A: Mislabeled specimens, hemolyzed specimens, clotted specimens, or wrong tube.
Q: Why are mislabeled specimens rejected?
A: Patient identification and safety cannot be confirmed.
Q: Why are clotted EDTA specimens rejected?
A: Clots affect accurate cell counts.
Q: Why are clotted heparin specimens rejected?
A: They can affect chemistry results.
Q: Why are wrong tube specimens rejected?
A: The additive may not match the required test.
Q: What is the number one STAT priority?
A: Patient bleeding out/trauma.
Q: What is the second STAT priority?
A: Chest pain requiring troponin testing.
Q: Why is trauma prioritized over chest pain?
A: Active bleeding is an immediate life threat.
Q: What is the STAT priority order?
A: Bleeding out/trauma → Chest pain/troponin → Routine testing.
Q: What should you do if a patient is sleeping before a blood draw?
A: Wake the patient and obtain cooperation/consent.
Q: Why should you wake a sleeping patient before collection?
A: They cannot provide active consent while asleep.
Q: How should you approach an unconscious patient?
A: Speak to them, explain the procedure, and treat them respectfully.
Q: Why should you talk to an unconscious patient?
A: They may still hear and understand what is happening.
Q: What is the rule for a language barrier during collection?
A: No consent means no draw.
Q: What should be done when there is a language barrier?
A: Use a translator or approved communication method.
Q: Can family members always translate for consent?
A: Follow facility policy; an approved translator may be required.
Q: What should you do if visitors or clergy are present during a non
urgent draw?
Q: What should you do if a STAT or timed draw is required and visitors are present?
A: Respectfully interrupt and explain the importance.
Q:* What is syncope?
A: Fainting or temporary loss of consciousness caused by decreased blood flow to the brain.
Q: What are common signs of syncope during blood collection?
A: Sweating, clammy skin, dizziness, pallor, and sudden silence.
Q: What is the first action when a patient experiences syncope?
A: Remove the tourniquet, remove the needle, apply pressure, and protect the patient.
Q: What is the STOP protocol for syncope?
A: Strip tourniquet, Take needle out, Observe/provide care, Pressure and document.
Q: Why should the tourniquet be removed during syncope?
A: To stop blood collection immediately and improve circulation.
Q: Why should the needle be removed during syncope?
A: To prevent injury while the patient is fainting.
Q: What should be documented after a syncope event?
A: The complication, actions taken, and patient response.
Q: What is a seizure?
A: A sudden uncontrolled electrical disturbance in the brain causing involuntary movements or altered awareness.