What is Venipuncture?

If a patient arrives in the emergency department feeling ill, most likely one of the first tests performed will be venipuncture, the act of drawing the patients’ blood by a skilled Phlebotomist.  Once collected, the patient’s blood will be transported to the laboratory.

Blood analysis has become one of the most widely used tools to quickly and accurately diagnose and treat patients. Collected by venipuncture, blood levels are also used to accurately monitor a patient’s health, perform routine screening such as cholesterol or glucose levels, to determine medication doses, for type and cross, as well as for blood bank collection.

The Phlebotomist utilizes those skills and procedures outlined during their education to determine the best way to obtain blood based on the patient’s age and what tests have been ordered. On-the-job experience will allow the Phlebotomist to learn ‘tricks’ that are useful in calming patients a bit apprehensive about venipuncture. Comfortable small talk may soothe and focus an elderly patient, while silly faces or kissing noises may provide some amusement to a child.

The phlebotomist will not collect the same amount of blood each time they perform a venipuncture. For some patients only one vial of blood may be collected. For a critically ill patient in the emergency department, the Phlebotomist may collect several vials of blood. The amount is determined by the test ordered by the Physician.

To perform venipuncture, the Phlebotomist will need a variety of tools. Frequently, a carrying tote or cart is utilized should the Phlebotomist need to travel to a patient’s room. The tote or cart, should contain syringes, needles in varying sizes, plastic catheters, various blood collection tubes, plastic hubs, several tourniquets, gloves, alcohol pads, patient labels, pens and Sharps container. In addition, cotton balls or 2×2 (sized) gauze pads, bandages and tape should be included.

Needles come in varying sizes – the higher the number, the smaller the needle. Some of the most commonly used are the 22 gauge (black top) and the 22 gauge (green top) as well as the 22 gauge butterfly needle (green label).  For infants and children, a smaller and more comfortable size is a 25 gauge butterfly needle (orange label).

Blood collection tubes are typically vacuum tubes, such as Vacuette or Vacutainer. While used in the United States as well as the UK, other parts of the world still use a syringe and butterfly needle instead. Vacuum tubes are particularly helpful because they allow a predetermined amount of blood to be drawn for each test. Some tests require blood to have an additive. These blood collection tubes are color coded depending on the additives.

Dispersed around hospitals as well as doctor’s offices, bright red Sharps containers can be seen. These containers are locked and visibly marked with Biohazard labeling. Once the Phlebotomist has performed venipuncture, the needles and any hubs are placed in these containers. This assures all blood contaminated needles are safely dispensed.

Before gloving, the Phlebotomist may palpate areas of possible venipuncture to determine which area, or site, is best to draw blood from. Because superficial veins aren’t blocked by anything such as an artery or tissues, they are easy to access. While blood can be obtained from several sites around the body, there are determining factors the Phlebotomist must consider, such as the patient’s age, size and type of tests ordered. Other factors such as the presence of scarring, hematoma or burns will necessitate another draw site. Patients who have undergone a mastectomy (partial or complete breast removal usually due to cancer) cannot have venipuncture performed on the same side of the body.

There are some areas where venipuncture cannot be performed, such as the foot. To draw blood from the foot requires specific physician authority because to do so may cause a blood clot in patients that are prone to thrombosis. Another area where venipuncture cannot be performed is the inside area of the wrist. This area is heavily laced with tendons and small arteries. Frequently, venipuncture will be performed on a hospital patient who has an IV. If the Phlebotomist observes the presence of an IV around a preferred blood draw site, care must be taken to obtain blood below the IV site, never above. If a cannula, fistula or a vascular graft is noted on a patient’s arm, another venipuncture site other than that arm must be found. Venipuncture cannot be performed on an artery, only a vein.

The phlebotomist can also obtain blood by performing a ‘finger stick.’ Unlike traditional venipuncture, this form only produces a small amount of blood and is used to check the glucose (sugar) levels of patients. A small lancet, a device around the size of a toothpick, is placed against a fingertip. When pushed, a tiny needle tip quickly jabs and as quickly retracts, providing a small droplet of blood for testing.

To collect blood from a child or infant, if a small amount of blood is needed for the tests ordered, the Phlebotomist may be able to obtain blood from the child’s heel. Known as a ‘heel stick,’ this form of venipuncture is quickly performed and less painful to the young child. Blood may also be obtained from scalp veins using a winged infusion needle.

One of the most popular areas to collect blood is in the median cubital vein. This vein is located in the crook, or bend, of the elbow (‘cubital fossa.’) The median cubital vein connects with the cephalic and basilica vein. This vein is easily visible, and in an area not heavily laced with nerves. Additionally, this vein is heavily secured, making the vein stable and not as likely to ‘roll’ making venipuncture easier. Most catheter and transfusion sites are in the median cubital vein.

Another popular venipuncture site is the basilic vein. Starting from the back of the hand, the basilic vein continues along the forearm to the axillary vein by the thorax. The basilic vein can be seen as a blue and rather large vein fairly close to the skin’s surface, making it visible and an easy venipuncture site.

Dorsal metacarpal veins are found on the front and back of the hand and can be drawn from.  Both the basilic and cephalic veins start in this network, and continue upwards towards the shoulder. The cephalic vein, known as the antecubital vein (familiarly called the ante-cube) is also a common venipuncture site.






Leave a Reply

Your email address will not be published. Required fields are marked *