What is Venipuncture?
While venipuncture can refer to a variety of procedures, including the insertion of IV tubes into a vein for the direct application of medicine to the blood stream, in phlebotomy venipuncture refers primarily to using a needle to create a blood evacuation point. As a phlebotomist, you must be prepared to perform venipuncture procedures on adults, children, and even infants while maintaining a supportive demeanor and procedural accuracy. Using a variety of blood extraction tools, you must be prepared to respond to numerous complications in order to minimize the risk to the patient while still drawing a clean sample.
In its entirety, venipuncture includes every step in a blood draw procedure—from patient identification to puncturing the vein to labeling the sample. Patient information, needle placement, and emotional environment all play a part in the collection of a blood sample, and it's the fine details that can mean the difference between a definite result and a false positive.
After placing the tourniquet and finding the vein, it's time for the phlebotomist to make the complex choice on what procedure will best suit the specific situation. Keeping this in mind, it should be noted that the following information is not an instructional guide on how to perform these phlebotomy procedures. Rather, the information below is intended to serve as an educational resource to inform you of the equipment and procedures you will use.
Venipuncture with an Evacuated or Vacuum Tube: This is the standard procedure for venipuncture testing. Using a needle and sheath system, this procedure allows multiple sample tubes to be filled through a single puncture. This procedure is ideal for reducing trauma to patients. After drawing the blood, the phlebotomist must make sure the test stopper is correctly coded and doesn't contact exposed blood between samples.
Venipuncture with a Butterfly Needle : This is a specialized procedure that utilizes a flexible, butterfly needle adaptor. A butterfly needle has two plastic wings (one on either side of the needle) and is connected to a flexible tube, which is then attached to a reservoir for the blood. Due to the small gauge of the needle and the flexibility of the tube, this procedure is used most often in pediatric care, where the patients tend to have smaller veins and are more likely to move around during the procedure. After being inserted into a vein at a shallow angle, the butterfly needle is held in place by the wings, which allow the phlebotomist to grasp the needle very close to the skin. Phlebotomists should be careful to watch for blood clots in the flexible tubing.
Venipuncture with a Syringe: This technique is typically only used when there is a supply shortage, or when a technician thinks it is the appropriate method. It uses the classic needle, tube, and plunger system, operating in a similar manner to the vacuum tube but requiring multiple punctures for multiple samples. Additionally, after the blood is drawn it must be transferred to the appropriate vacuum tube for testing purposes. If you choose to use this method, remember to check for a sterile seal, and use a safety device when transferring the sample.
Fingerstick (or Fingerprick): This procedure uses a medical lance to make a small incision in the upper capillaries of a patient's finger in order to collect a tiny blood sample. It is typically used to test glucose and insulin levels. When performing a Fingerstick, the phlebotomist should remember to lance the third or fourth finger on the non-dominant arm. Never lance the tip or the center of the finger pad; instead, lance perpendicular to the fingerprint lines.
Heelstick (or Heelprick): Similar to the Fingerstick procedure, this process is used on infants under six months of age. A medical lance is used to create a small incision on the side of an infant's heel in order to collect small amounts of blood for screening. As with a Fingerstick, the incision should be made perpendicular to the heel lines, and it should be made far enough to the left or right side of the heel to avoid patient agitation. Before performing a Heelstick, the infant's heel should be warmed to about 42 degrees Celsius in order to stimulate capillary blood and gas flow.
Therapeutic Phlebotomy: This involves the actual letting of blood in order to relieve chemical and pressure imbalances within the blood stream. Making use of a butterfly needle, this therapy provides a slow removal of up to one pint of blood. Though the blood removed is not used for blood transfusions, the procedure and concerns are the same as with routine blood donation. As with any phlebotomy procedure, one should pay close attention to the patient in order to prevent a blood overdraw.
Bleeding Time: A simple diagnostic test that is used to determine abnormalities in blood clotting and platelet production. A shallow laceration is made, followed by sterile swabbing of the wound every 30 seconds until the bleeding stops. Average bleed times range between one and nine minutes.
As a phlebotomist, you should familiarize yourself with the application and cross-application of these procedures in order to recognize when a procedure is necessary, and what the risks are for each.