Lab Test Procedure : PERFORMING A VENIPUNCTURE

Venipuncture Site Selection: The median cubital and cephalic veins are most commonly used for venipuncture. See below. Alternative sites are the basilic vein on the dorsum of the arm or dorsal hand veins. Due to its close proximity to the brachial artery and median nerve, the basilic vein, which is located on the pinkie side of the arm, should be used only if there is not another more prominent arm vein. Veins in the foot and ankle should be utilized only as a last resort. Veins on the underside of the wrist should be avoided. Certain other sites should also be avoided.


Sites to avoid:
• Extensive scarring from burns or surgery
• The upper extremity on the side that a mastectomy was performed.
• Hematoma – A venipuncture should not be performed on a hematoma, regardless of how small it may be. If there is not an alternate vein to draw, the venipuncture should be performed distal to (below) the hematoma.
• Intravenous therapy/Blood Transfusions – If it is not possible to draw the opposite arm, then blood should be drawn from BELOW (distal to) the IV. The tourniquet should be applied between the IV site and the venipuncture site. If drawing above the IV site is the only option, then the IV infusion must be turned off for at least 2 minutes before performing the venipuncture. As there is still a risk that the sample could be contaminated, you must document that the specimen was drawn above (proximal to) an IV site and how many minutes the IV was turned off before the draw occurred. The lab may reject the specimen as contaminated based on the test results.
• Cannula, Fistula or Vascular Graft – Blood should only be drawn from an arm with a cannula, fistula or vascular graft with the provider’s prior approval.
• Edematous extremities – tissue fluid accumulation can alter test results.
• Sites with noticable skin conditions, such as eczema or infection.

Palpate and trace the path of the vein with the index finger. Arteries pulsate, are more elastic and have a thicker wall than a vein. Thrombosed veins lack resilience, feel cord-like and roll easily. If you are using a tourniquet for preliminary vein selection, it should be released after one minute, left off for two minutes and then reapplied before performing the venipuncture.

Procedure and Performance of a Venipuncture:
• Select the proper size needle and attach it to the syringe or Vacutainer hub.
• When using a syringe, make sure that you pull the plunger in and out to assure free motion.
• Position the draw site for best visualization and/or palpation. Apply the tourniquet 3-4 inches above the selected puncture site. Do not place tightly or leave on for more than 1 minute. Instruct the patient to make a fist and hold it; do not have them pump their hand. Select the venipuncture site by palpating with the gloved index finger.
• Prepare the patient’s arm using a Chlorhexadine wipe. Allow to air dry. Do not dry the site with gauze and do not blow on the area to dry as this will contaminate the site. After cleansing the area, if it is accidentally touched before performing the venipuncture, it should be cleansed again.
• Grasp the patient’s arm firmly using your thumb to draw the skin taut and anchor the vein; do not use the index finger to pull the skin upward as this increases the risk of sticking yourself. Swiftly insert the needle through the skin, bevel side up, at a 15 – 30 degree angle with the skin, into the lumen of the vein.
• If the patient complains of “shooting, electric-like pain, or tingling or numbness proximal or distal to the puncture site,” the needle should be removed immediately. It is possible that a nerve has been punctured and possibly damaged. The venipuncture should be repeated in a different site. A Supervisor or Manager should be notified and the incident should be documented.
• If an arterial puncture is suspected, as indicated by a bright red, quick, pulsing flow, with or without rapid development of a hematoma, the needle should be removed immediately. Forceful, direct pressure should be applied to the site for a minimum of five minutes or until the bleeding has stopped. The nursing staff should be notified, and they in turn must notify the physician. A laboratory Supervisor or Manager should also be notified and the incident should be documented.
• If the blood does not begin to flow, reposition the needle by gently moving the needle either backwards for forwards in the arm. If the blood is flowing slowly, gently adjust the angle to see if the needle is sitting up against the wall of the vein. Loosen the tourniquet, as it may be obstructing blood flow. If you are vacutaining, try another tube – there may be no vacuum in the tube.
• After you have attempted to reposition the needle and are still not successful, remove the tourniquet, remove the needle and begin the process with a new site. In the case of a difficult venipuncture, an individual may make a maximum of two attempts before having someone else try. A third stick is allowable if a partial sample has been obtained and you as the drawer feel reasonably confident that you can obtain the specimen on the next try.
• When the collection is complete, remove the tourniquet and place gauze over the venipuncture site. While the needle is still in the vein, activate the safety button with the tip of the index finger; the needle will automatically retract from the vein and the safety device will cover the needle.
• Apply adequate pressure to the puncture site to stop the bleeding and avoid formation of a hematoma. If you used a needle and syringe, ask your patient or a parent to apply pressure to the site so that you can fill your tubes. Do not have the patient bend his/her arm; this may cause the arm to start bleeding when the arm is straightened out.
• If blood was drawn with a syringe, attach the blood transfer device to the syringe and fill tubes according to the ‘Order of Draw for a Venipuncture’ (see below).
• Dispose of the contaminated materials and needle in the appropriate waste containers.
• Mix and label all appropriate tubes at the patient’s bedside. Return to your patient and assess the site of the puncture. Apply a band-aid or CoFlex to the site. (See “Use of Band-Aids in the Post-Phlebotomy Policy)

Additional Considerations When Performing a Venipuncture: The following considerations should be taken into account:

• Preventing a Hematoma: puncture only the uppermost wall of the vein. Remove the tourniquet before removing the needle. Make sure the needle fully penetrates the upper-most wall of the vein; partial penetration may allow blood to leak into the tissue surrounding the vein. Adequate pressure should be applied to stop the bleeding once the phlebotomy is complete. A hematoma can cause a post-phlebotomy compression injury to a nerve.
• Preventing Hemolysis: Mix tubes gently, by inversion, 5-10 times – do not shake them. Avoid drawing blood from a hematoma. If using a needle and syringe, avoid drawing the plunger back too forcefully. Make sure the venipuncture site is dry. Avoid probing for the vein. If using a blood transfer device to fill vacutainer tubes, allow the vacuum to pull the blood into the tubes; do not use the plunger on the syringe to force the blood into the tubes more quickly.
• Preventing Hemoconcentration: An increased concentration of larger molecules and formed elements in the blood may be due to several factors including prolonged tourniquet application (greater than 1 minute), massaging, flicking, squeezing or probing the site, long-term IV therapy, and sclerosed or occluded veins.
• Preventing injury to a nerve, tendon, or muscle: Use careful palpitation and appropriate angle of entry. Excessive probing (uncalculated side-to-side movement) with the needle should be avoided.
• Preventing dizziness or fainting and potential follow-up injuries due to a fall: Be sure patient is seated in an appropriate draw chair and or lying in a bed. Have approriate back up staff as available.
• Preventing of infection: Follow proper infection control policies.
• Preventing injury from improper immobilization – Immobilize the patient with care. If there is any concern regarding injury, contact nursing for Inpatients and follow the Policy for Proper Handling of an Uncooperative Patient.

Order of Draw for Venipuncture: Blood collection tubes must be drawn in a specific order to avoid cross-contamination of additives between tubes. Follow the order of draw listed here for both syringes (utilizing the blood transfer device) and vacutainers:

1. Blood Cultures
2. Coagulation tubes – light blue top tube
3. Non-additive tube – red top tube
4. SST red or gold top – this tube contains a gel separator and clot
activators.
5. Sodium Heparin – green top tube
6. Lithium Heparin – green top tube
7. EDTA – lavender top tube
8. ACDA or ACDB – light yellow top tube
9. Oxalate/fluoride – light gray top tube

If Gases (venous – no O2 reported) are drawn with a needle and syringe, the blood must be put into the Lithium Heparin tube using a blood transfer device; do not pop the top of the tube open to fill the tube. Tubes with additives or clot activators must be thoroughly mixed by gentle inversion, 5-10 times. Shaking and vigorous mixing should be avoided.

References

Ernst, Dennis J. “Pediatric Pointers.” Center for Phlebotomy Education, Inc. 2004-2008, edited for accuracy 1/08.

Ernst, Dennis J. and Catherine Ernst. “Mastering Pediatric Phlebotomy.” Center for Phlebotomy Education, Inc. Adapted from Phlebotomy for Nurses and Nursing Personnel. HealthStar Press, Inc. 2001, updated 1/08.

Kiechle, Frederick L. So You’re Going to Collect a Blood Specimen: An Introduction to Phlebotomy, 11th Edition. Northfield, IL: College of American Pathologists, 2005.

NCCLS. Procedures for the Collection of Diagnostic Blood Specimens by Venipuncture; Approved Standard—Sixth Edition. CLSI document H3-A6. Wayne, PA: Clinical and Laboratory Standards Institute; 2007.

Proper Handling of an Uncooperative Patient in an Outpatient Setting – Akron Children’s Hospital

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