Lesson 6: PRE-ANALYTICAL CONSIDERATIONS IN PHLEBOTOMY

• The pre-analytical testing phase includes procedures such as laboratory handling and identification, which take place prior to any laboratory testing.
• Pre-analytical testing phase requires proper control measures placed to avoid subsequent issues.
• Pre-analytical testing phase starts when the doctor's order is given and ends when the laboratory testing has officially commenced.
• In pre-analytical testing phase, phlebotomist must also be able to identify factors that affect the process and address them as needed.
• Laboratory test is used by physicians to diagnose and monitor the presence of a disease.
• The physicians compare the test results to a reference range or reference interval.
• Reference interval shows the high and low limits of result values as compared to healthy individuals.
• Several factors are considered as part of the reference interval study or the interpretation of the data obtained.
• In phlebotomy, the basal state is ideal in establishing reference range.
• Basal state represents the condition of the metabolism of the body early in the morning or approximately 12 hours of fasting.
• Basal state can be influenced by age, gender, and conditions of the body.
• Physiological variables that influence laboratory results include: age, altitude, dehydration, diet, diurnal variation, drug therapy, exercise/IM injection, fever, gender, jaundice, intermuscular injection, position, pregnancy, smoking, stress, and temperature & humidity.
• Age is a physiological variable which affects RBC, WBC, and creatinine clearance
• Altitude is a physiological variable which affects RBC.
• Dehydration is a physiological variable which affects hemoconcentration, RBC, enzymes, iron, calcium, and sodium.
• Diet is a physiological variable which affects glucose, lipids, and electrolytes.
• Diurnal variation is a physiological variable which affects thyroid stimulating hormone, cortisol, and iron
• Drug therapy is a physiological variable which affects enzymes and hormones
• Exercise/IM injection is a physiological variable which affects creatinine kinase, pH, carbon dioxide partial pressure, glucose, and lactic acid dehydrogenase.
• Fever is a physiological variable which affects hormones and cortisol
• Gender is a physiological variable which affects RBC, hemoglobin, and hematocrit
• Jaundice is a physiological variable which results to yellow color interfaces due to increased bilirubin.
• Intramuscular injection is a physiological variable which affects creatinine kinase and skeletal muscle fraction of LDH
• Position is a physiological variable which affects protein and potassium
• Pregnancy is a physiological variable which affects RBC
• Smoking is a physiological variable which affects WBC, growth hormone, cholesterol, cortisol, glucose, and triglycerides.
• Stress is a physiological variable which affects adrenocorticotropic hormone, WBC, iron, catecholamine, and cortisol
• Temperature & humidity is a physiological variable which affects hemoconcentration
• Burns, scars, and tattoos are sites advisable not to choose because veins in the area may be difficult to examine and blood circulation may be impaired.
• Burns may be too painful to touch
• Tattoos may also be susceptible to infection due to dyes used that may interfere with the process
• Puncturing damaged veins may also produce inaccurate results.
• Damaged veins may be sclerosed or hardened, or thrombosed or clotted.
• Edema, also known as oedema
• Edema is an abnormal swelling caused by the accumulation of fluid in the tissues.
• The tissues in an edema may become fragile, making the task of locating the veins harder.
• Edema is a condition may be due to reactions from medications, pregnancy, infections, and other medical problems.
• Hematoma is a solid swelling or mass of blood in the tissues caused by the leakage of blood from the vessels during venipuncture.
• Selecting a venipuncture site with hematoma will be painful for the patient because it will obstruct the blood flow.
• Hematoma could also lead to contamination of blood sample.