Venipuncture
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Venipuncture (also known as phlebotomy or simply bleeding) is the process of obtaining blood from someone, from one of their veins. In many circumstances it will be done by a phlebotomist, although nurses, doctors and other medical staff are also trained to take blood.
Blood is most commonly obtained from the median cubital vein, on the anterior forearm (the side opposite the elbow). This vein lies close to the surface of the skin, and there is not a large nerve supply.
Venipuncture with vacuum tubes (vacutainers)
There are many ways which blood can be obtained from someone. The best method varies with the age of the patient, equipment available and tests required.
Vacutainers are a type of test tube that contain a vacuum that automatically aspirates blood into itself. They are commonly used in hospitals, private doctors offices and community labs, and are effective in most adult patients and older children.
Equipment needed includes: a plastic needle holder, hypodermic needles, an adjustable tourniquet, appropriate tubes, alcohol swabs, cotton wool, sticky tape, and a pen for labelling.
This is a rough procedure used when blood is collected with vacutainers.
- First of all, the patient should be identified -- a test result is useless if it's done on the wrong person. The test subject should be asked their name and date of birth. This should not be a yes or no to a question, e.g. Are you Stanley Jones? as many people will just agree.
- The vacutainer tubes needed for the tests required should be determined, and nearby ready to be used. The order that the tubes are used is often important, and should be known before puncturing the skin. Other equipment that will or may be needed should also be handy.
- A tourniquet should be placed on the arm where blood is to be collected. This should be just tight enough that blood collects in the veins.
- The vein to be used should be palpated; its depth, size and direction should be determined, and the best angle to puncture the skin planned.
- The skin around the area should be wiped with an alcohol swab (or iodine prep if drawing for blood culture) and allowed to air dry. An appropriate needle should be placed into a holder.
- The needle should be inserted into the vein with the bevel facing upwards. It should be pushed quickly and smoothly through the skin to minimise pain and to prevent blood from spouting out the bevel.
- Once the needle is in the vein, a vacutainer should be pushed into the needle holder. Care should be taken to ensure the needle does not move too much. The tube will fill itself up with blood.
- The tube can be removed once full, and the next one pushed into the holder.
- On the last tube, the tourniquet should be loosened or removed once blood starts to enter the tube.
- The last tube should be removed from the holder before the needle is pulled from the vein.
- The needle should be pulled out of the skin on the same angle it went in.
- Once the needle is removed, clean cotton wool should be pressed onto the wound, and the patient instructed to apply pressure to it. Doing this may minimise bruising.
- The tubes should be well mixed, and labelled straight away. The wound under the cotton wool should be checked, then the cotton wool taped to the patient's arm.