Capillary Puncture and Dermal Collection Flashcards

Which finger is the preferred site for capillary blood collection in adults?

Answer: Middle or ring finger

The middle and ring fingers are preferred because they have more tissue depth and are less calloused than the thumb or index finger.

What is the purpose of discarding the first drop of blood during capillary collection?

Answer: It may be contaminated with tissue fluid that can cause erroneous results

The first drop may be diluted with tissue fluid released during the puncture, which can affect test results.

Which area of the heel is recommended for capillary puncture in neonates?

Answer: The medial or lateral plantar surface

The medial or lateral plantar surface avoids the calcaneus bone and major nerves and arteries, making it the safe zone for heel sticks.

What is the maximum recommended puncture depth for a neonate heel stick per CLSI guidelines?

Answer: 2.0 mm

CLSI guidelines recommend a maximum puncture depth of 2.0 mm for neonatal heel sticks to avoid hitting the calcaneus bone.

In capillary blood collection, which specimen is collected FIRST when multiple collection devices are used?

Answer: EDTA (lavender) tubes

In capillary collection, EDTA tubes are collected first to ensure adequate anticoagulation before platelets begin to aggregate.

Which action should be avoided when collecting a capillary blood specimen?

Answer: Squeezing or milking the site excessively

Excessive squeezing dilutes the specimen with tissue fluid and can cause hemolysis, leading to erroneous test results.

What is the recommended method to increase blood flow to a site before capillary puncture?

Answer: Warm the site to approximately 42°C for 3 to 5 minutes

Warming the site to 42°C for 3 to 5 minutes causes vasodilation and increases arterial blood flow into the capillary bed.