Lesson 4 — Blood Collection Equipment, Additives, and Order of Draw Summary & Study Notes

🩺 Overview

This lesson covers the essential blood collection equipment, common antiseptics and disinfectants, types of phlebotomy needles and systems, categories of additives, and the correct order of draw to prevent cross-contamination. Short, clear understanding of these items ensures patient safety and specimen integrity.

🧰 General Equipment and Supplies

Blood drawing station — used primarily for outpatients and organized for procedure flow. Phlebotomy chair — comfortable seating with an arm rest to stabilize the limb. Equipment carrier — portable kits for STAT draws and carts for routine rounds.

Personal Protective Equipment (PPE) — includes gloves (single use per patient). Common glove types: sterile, non-sterile, nitrile, vinyl, neoprene, and disposable.

Other supplies: antiseptics (prevent skin bacteria from entering the puncture), disinfectants (clean surfaces and instruments), hand sanitizers, gauze pads (2×2 inch), bandages, glass slides (1×3 for hematology smears), pens/sharpies for labeling, watches/timers, and biohazard & sharps containers for proper disposal.

🩸 Venipuncture Equipment

Vein-locating device — transillumination tools to assist finding veins. Tourniquet — used to temporarily constrict venous blood flow. Needles — always single-use; available as multi-sample, hypodermic, and winged (butterfly) styles.

Needle gauge describes lumen diameter: the higher the gauge number, the smaller the lumen.

Evacuated Tube System (ETS) — a closed collection system with a multi-pointed needle, tube holder, and evacuated tubes; considered efficient and safe.

💉 Phlebotomy Needles and Syringe Systems

Multi-sample needles are designed for ETS. Hypodermic needles vary in gauge and length. Winged infusion (butterfly) needles are ideal for small or difficult veins (commonly 23–25 gauge with short tubing and a luer attachment for multi-sample compatibility).

Syringe method is an alternative for difficult veins: use a hypodermic needle with a plastic syringe (Luer lock tip); withdraw blood by pulling the plunger and transfer to tubes using a transfer device after a single draw.

🧴 Antiseptics and Disinfectants

Isopropyl alcohol is commonly used for skin antisepsis; it is reported as more effective than ethyl alcohol but has carcinogenic concerns only at very large exposures. Use appropriate contact time and drying before puncture.

Disinfectants are for instruments and surfaces; they differ from antiseptics which are for skin.

🧪 Categories of Additives

Additives are chemicals in tubes that modify the specimen (e.g., prevent clotting or preserve analytes). They may be sprayed-dried, liquid, or powdered. Proper mixing by inverting the tube 3 to 10 times (depending on tube type) is required to ensure interaction between additive and blood.

Anticoagulants prevent clot formation by either chelating calcium or inhibiting thrombin. Common examples include $EDTA$ (ethylenediaminetetraacetic acid), citrates, heparin, and oxalates. Special-use anticoagulants include acid citrate dextrose (ACD), citrate phosphate dextrose (CPD), and sodium polyanethol.

Thixotropic gel separators create a barrier between cells and serum/plasma after centrifugation, inhibiting cellular metabolism of analytes.

Trace-element–free tubes (usually royal blue top) are manufactured to avoid contamination for toxicology and trace element testing.

🎨 Additive Color Coding & Order of Draw

Adhering to the correct order of draw is essential to avoid cross-contamination of additives between tubes. Typical color sequence and purpose:

• Yellow (SPS) — $Sodium\ Polyanethol\ Sulfate\ (SPS)$ for blood cultures and specimen transport.
• Light blue (citrate) — $Sodium\ Citrate\ 3.2$ used for coagulation tests.
• Red (no additive) — non-additive tubes for serum.
• Green (heparin) — sodium or lithium heparin for plasma chemistry.
• Lavender (EDTA) — $EDTA$ for hematology (CBC) testing.
• Gray — $Sodium\ Fluoride\ or\ Potassium\ Oxalate$ for glucose preservation and other tests.
• Black — $Sodium\ Citrate\ 3.5$ used for specific ESR methods.

Follow local laboratory protocols for any variations and for special tubes (trace-element-free, polymer gel separators, etc.).

🔁 Tube Inversions (Mixing)

After collection, tubes containing additives must be inverted gently to mix blood with the additive. Typical guidance is 3 to 10 inversions depending on the tube and additive; do not shake vigorously as this may cause hemolysis.

✅ Key Safety and Quality Points

• Always use single-use needles and appropriate PPE for each patient.
• Ensure proper labeling immediately after collection.
• Allow antiseptic to dry to avoid hemolysis and contamination.
• Follow the order of draw consistently to prevent cross-contamination of additives and ensure accurate test results.
• Dispose of sharps and biohazard waste properly.

These concise notes summarize the essential equipment, procedures, and rationale behind correct blood collection technique and tube handling for reliable laboratory results.