Collection of Specimen 2024 PDF

Collection of Specimen Definition of Terms  Antecubital Space  located where the elbow ends  Arterial Blood Gas (ABG)  procedure that involves taking blood from an artery.  Artery – blood vessel that carries richly oxygenated blood from the heart to the body tissues. ...

Collection of Specimen Definition of Terms  Antecubital Space  located where the elbow ends  Arterial Blood Gas (ABG)  procedure that involves taking blood from an artery.  Artery – blood vessel that carries richly oxygenated blood from the heart to the body tissues.  Capillaries – tiny blood vessels that connect the smallest arteries to the smallest veins. Definition of Terms  Gauge  Hematoma  loss of blood from a vessel  Hemoconcentration – increase in the concentration of formed elements in the blood caused by lack of fluid in the blood.  Hemolysis – destruction or lysis of red blood cells  Lumen – cavity or channel within the tubular organ, such as blood vessel.  Phlebotomy – act of entering a vein with a needle for the purpose of obtaining venous blood. Definition of Terms  Thrombosis – blood clot in a vessel.  Tourniquet – device often a rubber band at least ½ inch wide, that reduces flow of blood in the veins and allows the veins become prominent.  Vacuum Tube System/Vacutainer System – system used for blood collection; uses a special disposable needle, a holder, and blood collection tubes that have little or no air.  Vein – blood vessels that carries deoxygenated blood from the tissues back to the heart  Venipuncture – procedure where a needle is inserted into a vein to obtain a venous blood sample GENERAL PRECAUTIONS IN COLLECTION OF BLOOD SAMPLES:  If a fasting specimen is required, confirm that the fasting order has been followed.  Always read the request first to see whether the examination is complete or incomplete, to determine the amount of blood needed.  Do not extract blood from patients while they are receiving intravenous medication because these solutions may influence the chemical analysis. GENERAL PRECAUTIONS IN COLLECTION OF BLOOD SAMPLES:  Never draw out the syringe without removing first the tourniquet to avoid hematoma.  Avoid prolonged application of tourniquet to avoid hemoconcentration.  The blood specimen collected with anticoagulants must be well mixed to prevent coagulation. TYPES OF SPECIMENS ANALYZED IN CLINICAL CHEMISTRY LABORATORY: Blood  Whole blood  Plasma and formed elements (unclotted) Blood  Serum  Liquid portion of clotted blood  Contains albumin and globulin  Preferred specimen in clinical chemistry because of the following reasons:  Certain substances like the lipemia clearing factor (LPL) are co precipitated during clotting  Clearer than plasma  There is no potential interference produced by anticoagulant Blood  Plasma  Liquid portion of unclotted blood  Contains albumin, globulin and fibrinogen  Advantages of plasma over serum:  There is no delay necessary in obtaining plasma by centrifugation of the whole blood  Usually a greater volume of plasma than serum is obtainable from a given volume of blood. Urine  24-hr sample  Random sample  Timed sample Other Body Fluids  CSF (cerebrospinal fluid)  Other specimens like ascitic fluid, peritoneal fluid, etc Timing of Collection  Fasting- “nothing by mouth” - generally 6 -14 hours  Random  24-Hour  Postprandial CLASSIFICATION OF METHODS AS TO SAMPLE REQUIREMENTS:  Macromethod  Micromethod  Ultramicromethod  Nanoliter method FACTORS CONTRIBUTING TO THE VARIATION OF RESULTS: Exercise  Transient or immediate effects (within the hour)  Elevated lactate  Elevated alanine  Elevated fatty acids  Long lasting effects  Increased activity of:  AST (SGOT)  CPK (CK)  LDH  ALD (Izoenzyme A)  Long term effects  Elevated concentration of sex hormones  Testosterone  Luteinizing hormone  Sex hormone binding globulin  Elevated concentration of steroids Fasting  Generally 6-14 hours  Elevated blood glucose, potassium, and lipids like cholesterol and neutral fats are seen in patients not under NPO and the reverse is true with inorganic phosphorous  Prolonged fasting has been associated with elevations in serum bilirubin, plasma triglycerides, glycerol, free fatty acids and a decrease in plasma glucose. Diet  Any diet immediately increases potassium and triglycerides  2-4 hours after fatty meal – increases ALP activity  High protein diet – increases urea, ammonia and urates with no significant increase in creatinine  Increase turbidity or lactescence – triglycerides level exceeds 4.6 mmol/L (4.0 g/L) Posture or position  Changes in position result to efflux of filterable substances from the intravascular space to the interstitial fluid spaces  Non-filterable substances increase in concentration Tourniquet application  One-minute application  Prolonged application results to:  Venous stasis  Anaerobiasis Tobacco smoke  Acute effects  Increase in plasma NEFA concentration  Increase in plasma cathecolamines and serum cortisol (due to nicotine) – affects the leukocyte peripheral count  Increase in neutrophils  Increase in monocytes  Increase in eosinophils  Chronic effects  Increase in total WBC count  Increase in blood hemoglobin values (carboxyhemoglobin)  Increase in mean corpuscular Volume (MCV) Alcohol ingestion  Increases plasma concentration of lactate, urate, acetate and acetaldehyde  Increases gamma glutamyl transferase concentration Stress (anxiety)  Affects hormone secretion  Results in hyperventilation leading to a disturbance in acid-base balance in the blood  Increases serum lactate  Increases plasma free fatty acids Drugs - antacids GENERAL METHODS OF BLOOD SAMPLE COLLECTION: CAPILLARY PUNCTURE  Formicromethod, ultramicromethod and nanoliter method  The method of choice for:  Pediatric infant  Geriatrics  Adults who are: CAPILLARY PUNCTURE/SKIN PUNCTURE/PRICK METHOD  Sites of puncture:  Palmar surfaces of fingertips  Plantar heel surface in infants  Plantar surface of the big toe  Earlobes CAPILLARY PUNCTURE/SKIN PUNCTURE/PRICK METHOD  Sites to be avoided:  Edematous area (swollen with fluid)  Cyanotic areas (purplish blue in color)  Scarred area  Traumatized area (black and blue)  Heavily calloused area CAPILLARY PUNCTURE/SKIN PUNCTURE/PRICK METHOD  Materials and Equipments:  70% isopropyl alcohol  Absorbent cotton sponges/balls or swabs  Sterile puncture instrument (lancet)  Capillary tube ARTERIAL PUNCTURE/ANAEROBIC  Generally used for the determination of blood oxygen, carbon dioxide tension and blood pH (Blood Gas Analysis).  Special training is required for this procedure  Tourniquet is not required  After removing the needle, apply moderate pressure with 2 x 2 sterile gauze until bleeding ceases  Insert needle (still attached to syringe) in stopper to prevent air from entering needle ARTERIAL PUNCTURE/ANAEROBIC  Sites of puncture:  Radial artery – most preferred site  Femoral artery (fem tap)  Brachial artery  Scalp artery  Umbilical artery ARTERIAL PUNCTURE/ANAEROBIC  Materials needed:  Syringe with gauge 21 needle with rubber cap  Cotton (wet and dry)  Alcohol or Iodine  Heparin - preferred anticoagulant  Warm towel (45ºC) – arterialization  Iced water bath – preservative for transport VENIPUNCTURE  Considered to be the most commonly used method of blood collection in Clinical Chemistry  Sample obtained is called venous blood VENIPUNCTURE  Sites of collection:  Veins in the antecubital fossa  Median cephalic vein –  Cephalic vein –  Basilic vein –  Vein of the longitudinal sinus or sagittal sinus  Femoral vein  Wrist vein  Jugular vein  Saphenous vein  Small saphenous vein  Great saphenous vein  Veins on the dorsal portion of the hand VENIPUNCTURE  Materials needed:  70% alcohol  Absorbent cotton or sterile swabs  Tourniquet  Syringe or Vacutainer set SYRINGE  Used for blood collection only  For single draw  Parts: a. Bevel d. Adapter b. Shaft e. Barrel c. Hub f. Plunger Advantages of venipuncture  Large amount of blood can be obtained  Ideal for blood chemistry determinations  It reduces the possibility of error in resulting from dilution with tissue juices. Disadvantages of venipuncture  Requires more time and skill  Requires more equipment  More complications may arise  hard to do on infants, children and obese individuals Procedure  Assembling equipments  Prepare the materials that will be needed in the procedure  Positioning and identifying the patient  Preparation of the needle and syringe  Applying the tourniquet Procedure  Selecting the vein  Applying the antiseptic  Inserting the needle Procedure  Releasing the tourniquet  Withdrawing the blood  Withdrawing the needle  Transferring the blood  Checking the patient wound COMPLICATIONS OF VENIPUNCTURE  Immediate Local Complications  Localized hemoconcentration or Venous stasis  Syncope or Fainting  Due to sudden decrease of blood supply to the brain  Remedy: Let the patient lie down COMPLICATIONS OF VENIPUNCTURE  Failure of blood to enter the syringe due to:  Excessive pull of the plunger which collapses the vein  Going through the vein reaching the musculature  Very small angle of entry wherein the needle reaches only the walls of the veins (transfixation of the vein)  Delayed Local Complications:  Thrombosis of veins  Formation of blood clots inside the lumen of the vein due to trauma  Thrombophlebitis  Inflammation of the vein due to thrombus as manifested by an inflammatory reaction on the outer skin surface  Hematomas  Blue or black skin discoloration commonly due to repeated trauma or puncture of the veins  General Delayed Complications:  Serum Hepatitis  AIDS COMMON DIFFICULTIES ENCOUNTERED DURING COLLECTION AND PROCESSING OF BLOOD Hemolysis  This must be avoided because of the following reasons:  Most constituents, such as SGOT, LDH, Acid Phosphatase and Potassium are present in large amount in erythrocytes  Invalidates determination due to color changes  May directly interfere in a chemical determination by inhibiting an enzyme such as lipase.  Hemoglobin may interfere with the diazotization of bilirubin. Hemolysis can be prevented by:  Proper collection of blood  Venous stasis  Moisture  Excessive traction  Small lumen needles  Air leak  Proper transfer of blood  Expelling of blood through the needle  Shaking  Separation of blood  Freezing  Over centrifuge LIPEMIA OR LACTESCENSE  This is caused by transient rise in chylomicrons following a meal containing fat  It causes interference with large number of chemical analyses because of turbidity.  It disturbs the following investigations particularly strongly:  Amylase  Bilirubin  Protein  SGOT  SGPT CONCENTRATION CHANGES  Thismay occur through dilution or evaporation.  The sources of the errors are:  Use of syringe and needles rinsed in saline solution  Use of liquid form of anticoagulant  Allowing the blood to stand in open container  Centrifugation of blood specimens in open containers. COMPOSITION CHANGES  Bacterial changes – such as formation of ammonia from urea  Enzymatic changes  Blood gas changes COMPOSITION CHANGES  Extravascular interchange – this is due to movement of substance between the cells and plasma or serum, like K, water and chloride.  Changes in lipid concentration – due to lipolysis  Changes in phosphates – due to hydrolysis of organic phosphate esters. Order of Draw