Venipunture refers to the process of collecting blood from a vein for the purpose of laboratory testing. Blood is collected into a tube attached to a needle, usually by drawing from a vein in the arm just inside the elbow. Although defined as an invasive diagnostic procedure, venepuncture is considered to be relatively safe with risk of few complications. Phlebotomists and other health care professionals trained to perform blood draws are required to follow specific guidelines for collecting and processing blood specimens.
- Skill level:
Things you need
- Appropriate colour-coded evacuated collection tubes
- Disposable 21- or 22-gauge needle
- Sterile alcohol wipes
- Sterile gauze pad
- Adhesive bandage
- Disposable non-latex gloves
Identify the patient. Check the wristband of an inpatient. Ask an outpatient for other identifying information such as date of birth to confirm identity. The Clinical and Laboratory Standards Institute (CLSI) sets phlebotomy standards for health care professionals who draw blood in the U.S. (see Reference 3) to ensure patient safety and standard of care.
Check the requisition order for patient information, tests to be performed and other special instructions.
Assemble all necessary equipment (listed above under Things You'll Need).
Determine the order of draw when multiple specimens have been ordered. The evacuated collection tubes have different colour rubber stoppers depending on the type of additive in the tubes. Blood samples for testing must be collected in the proper tubes.
Select the site by palpating the arm. Look for a full vein that springs back. Phlebotomists generally draw blood from the cephalic or median cubital veins; however, the basilic vein in the forearm is another frequently used site. Areas that should be avoided because of possible complications or erroneous test results include scarred areas, hematomas, the arm on the same side that a mastectomy was performed, veins in the feet and legs or the site above an IV cannula (a tube inserted into the arm to administer medication). Blood should not be drawn while a patient is receiving a blood transfusion.
Draw the sample. Position the patient with his or her arm extended; the wrist should be lower than the bend in the arm. Apply the tourniquet about three inches above the selected puncture site. Instruct the patient to make a fist so that the vein dilates. Sterilise the site with alcohol wiping in a circular motion. Insert the needle swiftly through the skin at a 15 to 30 degree angle. Perform the venepuncture in the same direction as the vein runs, lining up the needle with the vein. Blood is pushed through the veins in an upward direction toward the heart; therefore, you want to position the needle in the same direction as the blood flow. Hold the needle with the bevel up.
Remove the tourniquet while drawing the last tube of blood. Withdraw the needle, place gauze over the puncture site, and apply pressure. Check to see that the bleeding has stopped. Dispose of needles in a sharps container and other hazardous blood draw materials in the appropriate containers consistent with infection control procedures.
Mix and label the tubes. The label must indicate the patient's last name, first name and middle initial, patient ID number, date and time the specimen was collected, as well as the initials of the phlebotomist performing the venepuncture. Send the specimens to the lab for processing.
Tips and warnings
- Phlebotomists are required to wear gloves according to polices and practices of universal precautions. Frequent hand washing is another standard precaution.
- Confirm that the patient has followed any special dietary restrictions prior to having blood samples collected.
- A 21-gauge needle is used most often, except in cases where a vein is very small.
- If a hematoma appears while drawing blood, immediately remove the needle and apply pressure to the site for several minutes.
- Collecting blood from elderly patients can sometimes be more difficult as changes in the skin due to ageing make older people more susceptible to bruising. Decreased circulation can also make it harder to collect enough blood for samples.
- Do not try to draw blood from the same patient more than twice. Notify a nurse or doctor if two attempts at venepuncture have been unsuccessful.
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