Blood Collection Flashcards
Time and conditions for serum preparation after blood collection.
Centrifuge at 1000-2000 g (RCF) for 10 mins, separate serum or plasma from cells within 2 hours (except gel tubes).
Time frame for analyzing blood samples, and storage conditions if delayed.
Analyze within 4 hours, refrigerate for 48 hours, freeze at –20°C for longer storage.
Blood sample types used in clinical chemistry and preferred tests.
Serum and plasma (heparinized) are preferred for most tests; Serum > plasma for glucose, K, PO4, HCO3, Ck, Ast, Alb.
Difference in values between whole blood (WB) and plasma for glucose.
WB value < Plasma value for glucose by 10-15%.
Tests that use whole blood and their associated values for comparison.
HBA1C, ABG, POCTs; Cb value > VB value for glucose post-prandial, K, and VB value > CB value for Tp, Ca.
Venipuncture sites and techniques for blood collection.
Antecubital fossa (median, cephalic veins), dorsal hand/foot veins; tourniquet 3-4 inches above site, not longer than 1 min.
Standard antiseptic for routine venipuncture.
70% isopropyl alcohol.
Antiseptic for culture or hypoallergenic individuals during venipuncture.
70% isopropyl alcohol + iodophor/povidone-iodine/chlorhexidine.
Needle angle for venipuncture.
15-30 degrees.
Venipuncture method preferred for infants and children.
Butterfly/Winged Infusion Set.
Venipuncture method for multisample collection.
Evacuated Tube System (closed system + multisample collection).
Typical use of 20-gauge needle (Yellow).
For large-volume tubes or syringes used on patients with normal-size veins.
Typical use of 21-gauge needle (Green).
Standard needle gauge for routine venipuncture on patients with normal veins.
Typical use of 22-gauge needle (Black).
For older children, adults with small veins, or difficult veins requiring syringe draws.
Typical use of 23-gauge needle (Blue).
Used for infants, children, or hand veins of adults and difficult veins.
Typical use of 25-gauge needle (Orange).
Used to collect blood from scalp or tiny veins of premature infants (prone to hemolysis).
Needle length ranges for different types.
1-1.5 inches for multiple hypodermic, 0.5-0.75 inch for butterfly.
EDTA mechanism and its function.
Prevents coagulation by the same mechanism, binds calcium.
Function of Citrate as an anticoagulant.
Binds and removes calcium to prevent clotting.
Function of Oxalate as an anticoagulant.
Precipitates calcium (Ca2+).
Function of Heparin as an anticoagulant.
Inhibits thrombin, acts on anti-thrombin III to prevent clotting.
Clot activators used in blood collection.
Silica (celite/diatomite), Thrombin.
Role of Thixotropic Gel Separator.
Gel + silica (SST) or gel + heparin (PST) used for separating blood components.
Purpose of Antiglycolytic agents (Sodium Fluoride, Iodoacetate).
Inhibit urease/uricase to prevent glycolysis, affecting BUN and uric acid levels.
Use of Iodoacetate in assays.
Used for glucose assay along with BUN and uric acid.
EDTA for Whole Blood (WB) tests.
Used for HBA1c and TDM (Immunosuppressant WB).
EDTA for Plasma tests.
Preferred for lipids and lipoproteins (LPs).
EDTA’s routine use in clinical chemistry.
Not routinely used in CC (Citrate and Oxalate are not common for routine use).
Heparin use for Arterial Blood tests.
Used for ABG (Arterial Blood Gas), NH3 (Ammonia).
Heparin use for Plasma tests.
Used for most clinical chemistry tests, including special tests like markers for CHF (BNP, NT-BNP).
Clot activators and thixotropic gel use.
For STAT serum tests to provide short clotting times.
Antiglycolytic agents gray top tubes for .
“glucose, lactate, and ethanol testing.”
EDTA tube color.
Lavender/Purple top, Pink.
Citrate tube color and use.
Blue top, used for ESR (Erythrocyte Sedimentation Rate), Black top for ESR.
Oxalate tube color.
Gray top.
Heparin tube color.
Green top.
Silica tube color and use.
Red plastic tube (CT 30 mins for clotting).
Thrombin tube color and clotting time.
Orange top, clotting time 5 minutes.
Gel + Silica tube color.
Gold (Red or Tiger with black spots).
Gel + Heparin tube color.
Light green or green with gray spots.
Sodium fluoride iodoacetate tube color.
Gray top.
Order of draw in multiple collection using ETS.
Blood culture > Coagulation tubes > Serum tubes > Heparin > EDTA > Oxalate/fluoride.
Number of inversions for SPS/sterile, EDTA, oxalate/fluoride tubes.
8-10 inversions.
Number of inversions for coagulation tubes.
3-4 inversions.
Number of inversions for plastic and SST tubes with silica.
5 inversions.
Factors affecting evacuated tube quality.
Ambient Temperature:
High = Increased draw volume
Low = Decreased draw volume.
Factors affecting evacuated tube quality.
Altitude
High altitude (>5000 ft) = Decreased draw volume.
Factors affecting evacuated tube quality.
Humidity
High = Water migration inside tube
Low = Escape of water vapor from tubes.
Factors affecting evacuated tube quality.
Light
Affects CTAD tube for coagulation tests
CTAD: citrate, theophylline, adenosine, and dipyridamole
Indications for capillary puncture.
Newborn Screening (Heel stick), POCT, DM monitoring.
Sites for capillary puncture.
Heel (3rd or 4th), Finger, Big Toe, Ear Lobe.
Recommended length of lance blade for heel stick.
1.75 mm or < 2 mm.
Consequences of squeezing the capillary puncture site.
Dilution with tissue juice, Hemolysis affecting analytes.
Capillary order of draw
Blood gas > Slides/smears > Additives > Serum.
Warming for blood gas specimen
Arterialize capillary blood (mimics ABG).
Arterial puncture angles
Radial: 45°
Brachial: 45–60°
Femoral (last choice): 60-90°
What procedure?
Checks collateral circulation (radial artery)
Modified Allen Test
Preferred heparin for arterial blood
Lyophilized heparin (0.05 mL/mL).
powdered!!
