# Capillary Blood Sampling

## Overview

This module describes how to obtain a capillary blood sample by pricking the finger or foot.

## Indications

1. Glucose or haemoglobin testing
2. Bilirubin testing in babies
3. Rapid tests such as for HIV or COVID-19 antibodies

## Contraindications

1. Damaged or infected skin, or distorted anatomy at the site

## Patient information and consent

Always verify your patient’s identity and obtain informed consent before proceeding.

### How do I explain this procedure?

“I need to prick your finger (or your child’s heel) to get a drop of blood to test it.”

### What can my patient expect?

“You may feel a sharp prick, but it will only be painful for a moment. I’ll take a drop of blood for the test. The test results will be available within a few minutes.”

### What is my patient’s role?

“Fearing blood or needles is normal, but tell me if you have fainted from it. Keep as still as possible. Afterwards, press firmly on the area with cotton wool to prevent bleeding.”

## Preparation

### Documentation

1. Patient notes

### Equipment

## Site & Positioning

In babies and infants under walking age, the sides of the heel are used. In children of walking age and adults, the middle or ring fingers are preferred. Fingers should be punctured on the sides of the fingertip, with the lancet perpendicular to the fingerprint.

Uncooperative children may need to be

restrained

restrained

The parent should sit with the child on their lap, with their legs crossed over the child’s legs. The parent should tuck the child’s arm under their own, using one hand to hold the free wrist and the other to hold the elbow extended.

.

## Procedure

​​Follow medical asepsis with non-sterile gloves.

## Troubleshooting

I don't have a lancet available.

Gently but swiftly prick skin with a needle, preferably a small (brown) needle.

I didn't obtain bleeding with the prick.

Bleeding may be affected by skin being calloused and thick, or if the patient has cold extremities or poor circulation. Avoid

aggressive squeezing

aggressive squeezing

Aggressive squeezing may cause inaccurate results by mixing blood with fluid from the tissues; if unsuccessful at another site, apply pressure to the base of the finger and gently "milk" toward puncture site.

of the site. Try using a longer lancet or a needle and puncture a different finger.

## Risks

## References

1. WHO Guidelines on Drawing Blood: Best Practices in Phlebotomy. Geneva: World Health Organization; 2010. Available from: https://www.ncbi.nlm.nih.gov/books/NBK138661/
2. Jońca M, Krótki F, Tomasik P. The effect of disinfecting procedure on the glucose concentration using a personal glucose meter. Primary Care Diabetes. 2021;15(5):848-852.