Capillary / Dermal Puncture (Fingerstick) — Practice Checklist

Step-by-Step Procedure (10 steps)

1. 1.

   Verify the order and identify the patient with two identifiers.

2. 2.

   Select a puncture site: the lateral, fleshy part of the middle or ring finger in adults (avoid the thumb, index finger, and the very center of the fingertip).

3. 3.

   Warm the site if circulation is poor (warm compress, 3–5 minutes) to improve blood flow.

4. 4.

   Cleanse the site with alcohol and allow it to air dry completely before puncturing.

5. 5.

   Hold the finger firmly and puncture perpendicular to the fingerprint ridges using a sterile, single-use lancet.

6. 6.

   Wipe away the first drop of blood, which may be diluted with tissue fluid or alcohol residue.

7. 7.

   Allow a rounded drop to form naturally; avoid excessive squeezing ("milking"), which dilutes the sample with tissue fluid.

8. 8.

   Fill microcollection containers in the correct capillary order of draw: blood gas testing, EDTA (lavender), other additive tubes, then serum.

9. 9.

   Apply gentle pressure with gauze until bleeding stops.

10. 10.

    Label all containers at the bedside before leaving the patient.

Instructor Competency Checkpoints (5)

Your instructor or preceptor will be watching for all of these during sign-off.

• Selects an appropriate puncture site and avoids the thumb, index finger, and the exact center of the fingertip.

• Punctures perpendicular to the fingerprint ridges, not parallel.

• Wipes away the first drop before collecting the sample.

• Avoids excessive milking of the finger.

• Fills microcontainers in the correct capillary order of draw.

Critical Mistakes — Avoid These

• ⚠

  Milking or excessively squeezing the finger, which hemolyzes the sample and dilutes it with tissue fluid.

• ⚠

  Puncturing parallel to the fingerprint ridges, which makes the blood run along the ridges instead of forming a drop.

• ⚠

  Using a site that's too cold or poorly perfused without warming it first.

• ⚠

  Puncturing the thumb, index finger, or the exact center of the fingertip (closer to bone, more painful, higher infection risk).

• ⚠

  Failing to wipe away the first drop, which can skew results with tissue fluid contamination.