Venipuncture Equipment Reviewer

Blood Collection Systems

  • Evacuated Tube System (ETS) – most common method

  • Syringe System – manual aspiration

  • Winged Infusion Set (Butterfly) – for small/difficult veins

Needle Gauge Sizes & Color-Coding

Gauge

Color

Common Uses

18G (Large)

Pink

Trauma, rapid transfusion, blood draw

20G (Medium)

Yellow

IV access, blood collection, meds

21G (Standard)

Green

Routine blood tests, IM injections

22G (Fine)

Black

Pediatric, geriatric, smaller veins

23G (Very Fine)

Blue

IM injections, small vein blood draw

25G (Ultra Fine)

Orange

Subcutaneous injections (insulin, vaccines)

30G (Micro)

Purple

Insulin pens, superficial injections

Remember: Larger gauge number = smaller needle diameter

CLSI Order of Draw

Mnemonic: "Boys Love Ravishing Girls Like Dieters"

  1. Blood Culture – Yellow (SPS) / culture bottles → microbiology

  1. Light Blue – Sodium citrate → PT, aPTT, coagulation

  1. Red - plain → Serum, blood bank, Biochemistry

  1. Gold/ yellow (SST) – Clot activator ± gel → chemistry, serology

  1. Green – Heparin (Lithium/ Sodium)→ plasma chemistry

  1. Lavender (EDTA) – EDTA (Ethylenediaminetetraacetic acid) → CBC

  1. Gray – Sodium fluoride + potassium oxalate → glucose, lactate

⚠️ Follow this order to avoid additive carryover (e.g., EDTA can falsely alter calcium/potassium). If using a butterfly needle, use a discard tube before the light blue tube.

Tourniquet Guidelines

  • Apply 3–4 inches (7–10 cm) above the puncture site

  • Restrict venous flow only, not arterial

  • Do NOT exceed 1 minute — prolonged use causes:

    • Hemoconcentration

    • ↑ Potassium, protein, hematocrit (erroneous results)

Antiseptics

Antiseptic

Use

Key Notes

70% Isopropyl Alcohol

Routine venipuncture

Air dry 30 sec; do not touch after cleaning

Chlorhexidine (CHG)

Blood cultures, high-risk

Avoid in infants <2 months

Povidone-Iodine (Betadine)

Blood cultures (if no CHG)

Dry 1–2 min; circular motion

Benzalkonium Chloride

Alternative

For patients allergic to alcohol

Key Rules: Clean center → outward, do NOT repalpate, let antiseptic fully dry, sterile technique for blood cultures.

Fingers to Avoid in Dermal Puncture

Finger

Reason

Thumb

Often callused

Index finger

More nerve endings (painful)

Fifth finger

Insufficient tissue depth

Also avoid: Swollen, scarred, bruised, or previously punctured sites; mastectomy side fingers (unless ordered).

Newborn Screening

  • Performed 24–72 hours after birth via heel puncture

  • Blood applied to filter paper cards

  • Screens for: PKU, Congenital Hypothyroidism, Galactosemia

  • Let card air dry ≥3 hours; do not stack or touch blood spots

Common Dermal Puncture Complications

  • Hemolysis – RBC rupture from excessive squeezing, residual alcohol, or vigorous mixing → inaccurate results

  • Infection – From improper disinfection → may cause osteomyelitis

  • Osteomyelitis/Osteochondritis – Puncture too deep, contacts bone; avoid back of heel

  • Microclot Formation – Slow collection or delayed mixing → specimen rejection