The best sites for venipuncture are usually the superficial veins in the upper arms. Specifically, these veins are the median cubital vein, the cephalic vein, and the basilic vein. The main idea behind venipuncture is to draw blood for any number of diagnostic tests. Superficial veins, which are located close to the surface of the body, are typically the easiest to access. Experts usually recommend using superficial veins for venipuncture since they are not blocked by arteries and tissues the way many of the body’s deeper, thicker veins are. The arms are also usually a good choice because they can be accessed without much intrusion or inconvenience. There isn’t really a foolproof location, though, and patients who have a lot of scarring or who have suffered arm injuries in the past may need their blood drawn from some other part of the body.
Venipuncture is a common medical practice that’s used to get blood for testing. A trained medical practitioner will insert a needle and syringe directly into the patient’s vein, and then withdraw blood as it’s coursing through the body. When the procedure is done properly, patients may feel pressure but shouldn’t experience pain. Much of the procedure’s success depends on the location of the needle and the skill of the technician, though. Experts usually look for veins that are near the surface of the skin to avoid having to push too deep. The veins need to be strong and also need to have a good flow of blood running through them, and a lot of this depends on the individual.
Technicians are usually trained to identify three main sites for venipuncture on a patient’s arm. In most cases one of these will be suitable; if not, blood may have to be drawn from elsewhere.
Median Cubital Vein
The median cubital vein is located in what’s known biologically as the “antecubital fossa,” which is where the arm bends towards the elbow. This vein is one of the best sites for venipuncture because it is usually large enough to see and feel. A few risks associated with drawing blood from this vein include the possibility of penetrating the brachial artery and biceps tendon. Since these tissues are located underneath the median cubital vein, care must be taken to avoid using too much force and puncturing too deeply.
The cephalic vein is found in both the forearm and the upper arm. It can be followed to where it empties into the auxiliary vein in the armpit. Health care providers often like to use the cephalic vein since it is more visible for access than other veins. Experts have reported that the cephalic vein sometimes “rolls” during venipuncture, though, which is to say that it pulsates and shifts as the blood is coursing through it; this can make slow and careful extraction more challenging. It’s usually best to start in the forearm rather than in the upper arm to avoid this.
One of the other common sites for venipuncture is the basilic vein. It is a main superficial vein located in the arm the runs alongside the inner areas of the forearm and upper arm. The basilic vein divides to join the brachial vein. When health care providers want to collect blood from this vein, they usually start in the forearm, the same as they would for the cephalic vein; in the upper arm, the basilic vein turns inward to become much deeper and harder to access.
Dangers of Poor Placement
Venipuncture can technically be performed from almost anywhere, but the best sites are usually those that are easy to access and that don’t carry risks of injury or irritation. Inappropriate sites include an arm in which blood is being transfused, since this can put undue pressure on the vein and possibly lead to its collapse; sites above an intravenous cannula, a device used to control delivery of intravenous (IV) fluids; or scarred areas.
In general health care providers should not use any site below the wrist, either. The hands are normally considered a “no draw area” because of the increased risk of hitting the ulnar or radial nerve, which controls hand movement and sensitivity. Doing so may cause permanent nerve damage and patients can lose the ability to close their hand to make a fist, among other things.