Phlebotomy Preanalytical Variables, Specimen Quality & Troubleshooting

What does the preanalytical phase encompass?

All operational steps and physiological conditions from the moment a laboratory test is ordered until the analytical testing process begins.

Why is adherence to protocol critical in the preanalytical phase?

It accounts for the majority of laboratory diagnostic errors, impacting accurate patient outcomes.

What skills must phlebotomists integrate?

Advanced technical skills and critical thinking to control variables affecting analytical results.

What is the basal state?

The resting metabolic condition of the body early in the morning, approximately 12 hours after the last food intake.

Why is establishing a basal state important?

It eliminates transient metabolic variations, providing a reproducible physiological baseline for evaluating reference intervals.

What intrinsic factors influence baseline reference ranges?

Age, biological sex, physical activity levels, emotional and physiological stress, nutritional status, and dietary intake.

What is a delta check?

An automated or manual quality control audit comparing a patient's current laboratory test results with previous results.

What do significant discrepancies in delta checks indicate?

Potential preanalytical errors or acute changes in patient clinical status.

How does age affect laboratory values?

It influences baseline reference values for RBC count, WBC count, creatinine clearance, and hormone concentrations.

What effect does altitude have on analytes?

Increased RBC count, hemoglobin, hematocrit, CRP, and uric acid; decreased urinary creatinine and plasma renin levels.

What is the impact of dehydration on laboratory results?

It causes hemoconcentration, artificially increasing levels of RBCs, serum enzymes, iron, calcium, sodium, potassium, and coagulation factors.

How does dietary intake affect laboratory results?

It alters circulating levels of glucose, serum lipids, and electrolytes prior to specimen collection.

What is the significance of diurnal and circadian variation?

Cyclic fluctuations influence specific analytes, requiring standardized collection timing for accurate results.

How can drug therapy affect laboratory results?

Pharmacological agents can alter circulating levels of diagnostic enzymes and endocrine hormones.

What changes occur due to physical exertion?

Shifts in acid-base balance and cellular leakage can affect blood pH, PCO2, CK, LDH, and blood glucose levels.

What is the effect of fever on laboratory results?

It induces altered metabolic states and endocrine stress responses, disrupting hormone concentrations.

How does biological sex influence laboratory values?

Endocrine and muscular differences create divergent baseline ranges, particularly for RBC counts, hemoglobin, and hematocrit.

What complications arise from intramuscular injections?

Localized trauma can elevate serum CK and LDH due to cellular leakage.

What is jaundice and its effect on laboratory testing?

Severely elevated bilirubin causes discoloration and spectrophotometric interference in automated testing.

How does posture affect laboratory results?

Changing from supine to upright posture drives fluid shifts, concentrating non-diffusible blood elements.

What is the impact of pregnancy on laboratory values?

It results in physiological hemodilution, lowering measured baseline RBC counts.

How does smoking affect laboratory results?

It elevates cholesterol, cortisol, glucose, GH, triglycerides, RBC counts, and WBC counts.

What is the effect of physical or psychological stress on laboratory values?

It transiently spikes WBC counts, iron, ACTH, catecholamines, and cortisol.

What happens during acute exposure to heat?

It stimulates vasodilation and fluid shifts, increasing intravascular plasma volume.

What are the complications of using burns, scars, and tattoos as venipuncture sites?

They exhibit poor microcirculation, increase infection risk, and complicate palpation.

What issues arise from puncturing edematous tissue?

It introduces tissue fluid contaminants, leading to hemodilution and invalid results.

What is a hematoma and its effect on laboratory results?

A localized blood collection that can yield hemolyzed samples not reflecting circulating concentrations.

Why should venipuncture be avoided on the arm ipsilateral to a mastectomy?

It elevates infection risk and alters chemical analyte concentrations due to disrupted lymphatic drainage.

What challenges does obesity pose for vascular access?

Peripheral veins are deeply seated within subcutaneous adipose tissue, making them difficult to visualize or palpate.

What are the risks associated with drawing blood from paralyzed limbs?

Reduced vascular tone, compromised venous return, and increased susceptibility to thrombosis require caution and alternate site prioritization.

Why should blood collection avoid an extremity with an active IV line?

To prevent significant dilution and contamination by infusing fluids or pharmacological agents.

What should be done if no alternative site exists for blood collection near an IV line?

Collection must take place downstream (distal) to the IV site, following institutional protocols.

What is the purpose of arterial lines in phlebotomy?

They provide continuous hemodynamic pressure monitoring and access to arterial blood gas.

What should phlebotomists never do with arterial lines?

They must never use arterial lines for routine venipuncture collection.

What are AV shunts and fistulas used for?

They are permanent connections between an artery and vein for hemodialysis access.

What precautions must be taken with an extremity bearing an AV shunt or fistula?

Venipuncture and blood pressure cuff placement are prohibited to avoid complications.

What are the roles of trained personnel regarding CVADs and PICC lines?

Blood collection through these devices is restricted to trained, certified nursing or medical personnel.

What should be done if a patient has allergies before a procedure?

Identify preexisting allergies and implement non-reactive materials to prevent allergic reactions.

What management is required for excessive bleeding in patients on anticoagulants?

Maintain continuous, firm manual pressure until bleeding ceases before applying a bandage.

How should fainting patients be managed during blood collection?

Perform collections in a recumbent position and support the patient if they show pre-syncopal symptoms.

What actions should be taken if a patient shows signs of nausea during a draw?

Terminate the draw, provide an emesis basin, and remain with the patient until symptoms resolve.

What should be done immediately if a patient has a seizure during venipuncture?

Withdraw the needle, protect the patient from injury, and summon emergency medical help.

What causes hematoma formation during venipuncture?

It can be caused by needle bevel over-penetration, partial vein insertion, or failing to remove the tourniquet before needle extraction.

What is iatrogenic anemia?

Anemia induced by excessive blood volume removal, posing severe risks to vulnerable patients.

What is the primary prevention method for infection during venipuncture?

Maintain strict sterile protocols and ensure antiseptics air dry completely.

What should be done if a patient reports severe pain during venipuncture?

Withdraw the needle immediately and abort the attempt.

What is hemoconcentration and what causes it?

It is caused by prolonged tourniquet application, leading to artificial concentration of blood components.

What is hemolysis in blood specimens?

It is the rupture of red blood cell membranes, releasing hemoglobin and other intracellular components into the plasma.

What can cause specimen contamination during blood collection?

Residual antiseptics, glove powder, or expired tubes can introduce foreign elements into the collection tube.

What is the systematic troubleshooting algorithm for phlebotomy?

STOP → ASSESS → CORRECT.

What should be checked if blood does not enter the collection tube?

Confirm the evacuation tube is fully pushed onto the needle and assess the needle bevel orientation.

What should be done if a vein collapses during blood collection?

Disengage the vacuum tube and wait for the vein to refill before attempting again.