2 Venipuncture Technique

Purpose and preparation

Venipuncture is the collection of blood from a vein. A safe, well-organized technique helps protect both the patient and the collector and supports accurate test results. Follow facility procedures and test-specific instructions because collection equipment and tube requirements can vary.

Identify the patient and select a site

Confirm the patient and requested tests using the required identifiers. Explain the procedure, check for relevant precautions or allergies, and position the patient seated or lying down with the arm supported and extended.

Choose a suitable vein by palpating rather than relying on sight alone. The Median cubital vein in the antecubital area is often preferred, and the cephalic vein may also be suitable. Select a vein that feels resilient and is well anchored. Avoid bruised, swollen, scarred, or otherwise unsuitable areas, and follow local policy for sites affected by an IV, fistula, or other clinical restriction.

Prepare the puncture site

Apply the Tourniquet above the intended puncture site, tight enough to slow venous return without stopping arterial flow. Keep it on for as little time as possible and follow facility limits. Ask the patient to make a fist, but not to repeatedly pump it.

Clean the site with the approved antiseptic, commonly $70\%$ alcohol, using friction, and allow it to air-dry completely. Do not touch the cleaned site; if it is touched, cleanse it again.

Insert the needle

Put on gloves and assemble the appropriate safety needle, holder, and tubes. Check that supplies are intact and that the tubes match the requested tests. Anchor the vein by gently drawing the skin taut below the site.

With the bevel facing up, align the needle with the vein and insert it smoothly at a shallow angle, typically about $15\text{ to }30^\circ$, adjusted to the vein’s depth. Keep the needle steady and avoid probing.

Collect and fill the tubes

Attach the first evacuated tube to the holder needle without moving the needle in the vein. Let the tube fill until blood flow stops, then remove it from the holder. For multiple tubes, follow the laboratory’s required Order of draw to reduce additive carryover.

A common sequence is blood cultures, citrate (light blue), serum, heparin (green), EDTA (lavender/pink), then fluoride/oxalate (gray). Confirm local requirements, including any special tubes. Fill each tube to its intended volume; this is especially important for citrate tubes, which require the correct blood-to-additive ratio. Gently invert additive-containing tubes as directed by the manufacturer or laboratory procedure; do not shake them.

Release the tourniquet once blood flow is established and before withdrawing the needle. Ask the patient to relax the fist.

Withdraw the needle and control bleeding

Remove the final tube from the holder and place clean gauze lightly over the puncture site without pressing down on the needle. Withdraw the needle smoothly, activate its Safety feature, and immediately discard the needle and holder in an approved sharps container. Never recap a used needle.

Apply firm, continuous pressure to the site with the arm extended until bleeding stops. Check that bleeding has stopped before applying a bandage. Give extra attention to patients who may bleed more easily, and follow local escalation procedures if bleeding persists or a hematoma develops.

Label specimens and complete aftercare

Label tubes at the patient’s side according to policy, verify the labels against the patient and orders, and follow any special specimen-handling instructions. Check the patient’s condition and provide brief aftercare advice, such as keeping pressure on the site if bleeding restarts.

The procedure depends on maintaining a suitable site, clean and dry skin, steady needle placement, correct tube order and fill volume, safe needle disposal, and pressure until bleeding stops.

• Citrate tube