Capillary blood sampling in Pediatrics

Capillary blood sampling in pediatrics is a minimally invasive method of collecting small volumes of blood by puncturing the skin—typically the heel in neonates or finger in older children. It’s widely used for routine tests like blood glucose, bilirubin, hematocrit, and blood gases, especially when venous access is difficult or needs to be preserved.

Indications

Preparation for Capillary Blood Sampling

• Assess the child for signs of poor perfusion, local edema, infection at the site, and impaired blood coagulation. The presence of these findings can lead to inadequate sampling, blood specimen contamination, increased pain, and infection.
• Avoid edematous area because the presence of fluid can contaminate blood specimen.
• Rotate the sites of puncture to decrease complications.
• Apply topical anesthetic (e.g., lidocaine) for finger stick procedure as time allows, based on child’s preference.
• Do not use lidocaine if the child is receiving methemoglobin-inducing agents, for example, sulfonamides and acetaminophen.
• Question the parents about the existence of coagulation disorders in the family history and previous signs of blood dyscrasias.
• Verify physician’s order for laboratory test.
• Explain the procedure to parents and child as appropriate. Prepare the child as appropriate. Provide therapeutic play or involve the child to help with the procedure.
  Encourage the parents to remain with the child during the procedure.
• Discuss with the parents about comfort measures. For example, swaddling, use of sucrose pacifiers, and distraction techniques that they can use with their child.

Procedure

• Apply warming devices to the area for 5-10 minutes before puncture (warm cloth <109°F or 42.8°C).
• Perform hand hygiene and don gloves.
• Remove warming device.
• Select and identify the puncture site:
• Heel:< 18 months
• Lateral to an imaginary line drawn from the middle of the great toe and running parallel to the medial aspect of the heel. Never puncture the back of the infant’s heel because that calcaneus is closest to the surface in that location.
• Finger: >18 months.
• The side of the third or fourth finger near the tip.
• Clean the puncture site with the antiseptic and allow drying for 30 seconds. Then dry with the sterile gauze.
•  If topical anesthetic has been used, remove before cleaning.
• Place extremity in dependent position while gently applying intermittent pressure to surrounding area; collect the blood in appropriate container.
• When using the capillary tubes or micropipettes, hold horizontally to fill them by capillary action and fill two-third to three-fourth full. Cover the end with your finger when transferring the specimen to bed side test tube.
• Elevate the extremity above heart level. Gently press dry sterile gauze to puncture the site until bleeding stops.
• Do not use bandages.
• Properly dispose of contaminated equipment. Put the lancing device in sharps container and blood-soaked gauze in biohazard bag.
• Remove gloves and perform handhygeine.
• Perform bedside laboratory testing or label the specimen with child’s name, IP. No., and date and time of collection, and sign it.
• Transport specimen to laboratory in appropriate manner.
• When using capillary tubes or micropipettes, hold horizontally to fill them by capillary action and fill two-third to three-fourth full (Figs. 3.6A to C). Cover the end with your finger when transferring the specimen to bed side test tube.
• Elevate the extremity above heart level.
  Gently press dry sterile gauze to puncture site until bleeding stops.
• Do not use bandages.
• Properly dispose of contaminated equipment. Put the lancing device in sharps container and blood-soaked gauze in biohazard bag.
• Remove gloves and perform hand hygiene.
• Perform bed side laboratory testing or label the specimen with child’s name, I.P.
  No., and date and time of collection, and sign it.
• Transport specimen to laboratory in appropriate manner (e.g., ice, refrigeration).

Aftercare

• Monitor the child for signs of pain and involve the parent in providing comfort measures. For example, rocking, cuddling. swaddling, talking in a quiet and soothing voice, providing pacifiers, praise, and presenting a small reward.
• Assess puncture wound daily for signs of infection, scaring, and calcified nodules, or bruising.
• Document the following: Date and time, site of puncture, specimen obtained, amount of blood loss, and child’s response to procedure.
• Maintain running total of blood loss in neonate or when multiple blood samples are being obtained.

Special Considerations

• Avoid excessive squeezing—can cause hemolysis or dilute the sample.
• Rotate sites to prevent tissue damage or scarring.
• Use aseptic technique to reduce infection risk.
• Monitor for bruising, bleeding, or poor perfusion.

REFERENCES

1. Annamma Jacob, Rekha, Jhadav Sonali Tarachand: Clinical Nursing Procedures: The Art of Nursing Practice, 5th Edition, March 2023, Jaypee Publishers, ISBN-13: 978-9356961845 ISBN-10: 9356961840
2. Omayalachi CON, Manual of Nursing Procedures and Practice, Vol 1, 3 Edition 2023, Published by Wolters Kluwer’s, ISBN: 978-9393553294
3. Sandra Nettina, Lippincott Manual of Nursing Practice, 11th Edition, January 2019, Published by Wolters Kluwer’s, ISBN-13:978-9388313285
4. Marcia London, Ruth Bindler, Principles of Paediatric Nursing: Caring for Children, 8th Edition, 2023, Pearson Publications, ISBN-13: 9780136859840.
5. Ernstmeyer K, Christman E, editors. Nursing Fundamentals [Internet]. 2nd edition. Eau Claire (WI): Chippewa Valley Technical College; 2024. PART IV, NURSING PROCESS. Available from: https://www.ncbi.nlm.nih.gov/books/NBK610818/

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