Collection Equipment and Needle Gauges
Pick a needle smaller than the vein (21 gauge is the usual adult choice), prefer a closed tube-holder system, and check every device for expiry, damage and a sealed package before use.
Needle gauge by patient (WHO Table 3.1)
| gauge | who it suits | length or device | source |
|---|---|---|---|
| 16-18 | Blood donation only (16 gauge is usually built into the donor bag) | Donor bag needle | WHO 2010, Table 3.1 and 4.2.1 Step 4 |
| 19-20 | Marked not applicable (NA) for routine adult, paediatric and neonatal draws in WHO's table | - | WHO 2010, Table 3.1 |
| 21 | Adults; the usual adult size | 1 to 1.5 inch | WHO 2010, Table 3.1; Merck Manual |
| 22 | Adults; also children, older adults and small veins | 1 inch | WHO 2010, Table 3.1; Merck Manual |
| 23 | Adults (straight needle); children, older adults, small veins and newborns (winged set) | 1 to 1.5 inch straight; 0.5 inch winged set | WHO 2010, Table 3.1 and 6.2.2 |
| 25 or finer | Avoid for children's venipuncture: linked to more hemolysis | - | WHO 2010, 6.2.2 |
The higher the gauge number, the thinner the needle.
Choose a needle that fits the most prominent vein with little discomfort and is smaller than the vein: too large tears the vein (hematoma); too small damages red cells (WHO 2010, 3.1.1 and Table 3.1).
The Korean Society for Laboratory Medicine (2025) also lists 23 or 25 gauge winged needles for infants and children to prevent vein collapse; WHO advises against 25 gauge or finer because of hemolysis. Follow your facility's procedure.
Preview only. The full sheet also covers: Collection systems; Insertion basics; Quality checks before every draw; After the draw.
Sources
- WHO Guidelines on Drawing Blood: Best Practices in Phlebotomy (2010); official WHO IRIS PDF, also published as NCBI Bookshelf NBK138650 · World Health Organization
- How To Do Venous Blood Sampling (Merck Manual Professional Edition, procedure page) · Merck & Co., Inc. (Merck Manuals)
- Chang J, et al. Standards and Practice Guidelines for Venous Blood Collection: Consensus Recommendations from the Korean Society for Laboratory Medicine. Ann Lab Med 2025;45(4):343-357 (PMC12187494) · Annals of Laboratory Medicine via PubMed Central
- 29 CFR 1910.1030 Bloodborne Pathogens · Occupational Safety and Health Administration
Free Routine Blood Collections practice questions
- Question 1Under CLIA, a laboratory's written labeling procedure must call for the patient's name or a unique identifier and, when appropriate, which other item?
- Question 2Croatian national recommendations allow tubes to be labeled after the draw only if the patient is still seated in front of the phlebotomist. Why?
- Question 3According to MedlinePlus, emergency services should be called when a seizure lasts longer than how long?