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What does a skin puncture collects?

What does a skin puncture collects?

Skin puncture blood is a mixture of undetermined proportions of blood from arterioles, venules, capillaries, and interstitial and intracellular fluids. The arterial portion can be increased by warming the site prior to collection. This increases the blood flow as much as sevenfold.

When do you get blood specimen by a skin puncture?


  1. Position the patient so that the hand is easily accessible.
  2. Cleanse the fingertip of the 3rd (middle) or 4th (ring) finger with an alcohol prep.
  3. Using a sterile lancet, puncture the fingertip in the fleshy part of the finger, slightly to the side.
  4. Wipe away the first drop of blood with a sterile 2×2 gauze.

Where is a skin puncture performed?

puncture site. Recommended skin puncture sites are the finger for adult patients and older children and the heel for infants and younger children.

What are the common skin puncture sites?

The distal end of the third or fourth finger is the most commonly used site. The very tip of the finger should not be punctured because there is a greater chance of puncturing bone as the bone is close to the skin surface. Puncture the fleshy pad on the end of the finger, slightly off center.

What are disadvantages of skin puncture?

Infection (a slight risk any time the skin is broken) Scarring (occurs when there have been multiple punctures in the same area) Calcified nodules (sometimes occurs in infants, but usually disappear by 30 months of age)

When is a skin puncture appropriate?

Skin puncture is especially applicable for severely burned patients, extremely obese patients, patients with thrombotic tendencies, geriatric patients, patients in whom superficial veins are either not accessible or are very fragile, and point of care testing.

What finger is not allowed in capillary collection?

The thumb (1) is to be avoided because it has a pulse. The index finger (2) tends to be more calloused, which would make collection of the specimen more difficult. This area is also more sensitive for the patient. The pinky finger (5) does not have sufficient tissue depth to prevent injury.

How Deep is a skin puncture?

The recommended depth for a finger-prick is: for a child over 6 months and below 8 years – 1.5 mm; for a child over 8 years – 2.4 mm.

What tests Cannot be performed on capillary blood?

Certain tests cannot be performed on capillary blood due to the large volume they require or the possibility of contamination. These include the following: Westergren erythrocyte sedimentation rate (ESR) test, due to large blood volume required.

What should be done before puncturing the skin?

Prepare the skin puncture site. Cleanse the area with 70% alcohol pad. Care must be taken with small infants so as not to injure the delicate skin tissue. Allow alcohol to dry.

Why is it important to wipe the first drop of blood?

The first drop of blood from a lancing site contains a greater volume of platelets, which could make the lancing site seal up before enough blood was obtained for the test, and the dual wipe ensured a longer, larger flow of blood.

When to use skin puncture for blood collection?

The skin puncture method for blood collection is used when it is impossible or impractical to obtain a venous blood sample. The following disadvantages of this technique should be considered whenever selecting this method as an option.

Which is the best site for a skin puncture?

Make the puncture across and not parallel to the whorls of the fingerprint. The third and fourth finger are the preferred sites because the thumb has a pulse, the index finger may be calloused or sensitive, and the fifth finger has insufficient tissue depth to prevent bone injury.

Which is preferred capillary puncture site Chapter 10 flashcards?

A) It is comforting to the patient. B) It increases blood flow up to seven times. C) It makes the veins more visible. D) It minimizes hemolysis of the specimen. Which of the following is a preferred capillary puncture site?

How is skin puncture blood different from venous blood?

Skin-puncture blood is a mixture of blood from arterioles, venules, and capillaries and contains interstitial and intracellular fluids. The proportion of arterial blood is greater than that of venous blood due to the greater pressure in arterioles than venules.