How is a blood test carried out
What is a blood test?
Blood tests are a very useful diagnostic tool. Blood is made up of several different kinds of cells and other compounds, including various salts and certain proteins. When blood clots outside the body, the blood cells and some of the proteins become solid. The remaining liquid is called serum, which can be used in chemical tests and in tests to find out how the immune system fights diseases.
What do doctors examine in the blood?
Blood contains two main elements: the fluid that is called plasma and cells. There are three kinds of cells: red blood cells, white blood cells and platelets. To get the information they need from the blood, doctors actually do several tests with the blood sample. These include measurements of the levels of the cells and a blood smear. A blood smear is a film of blood placed on a slide to allow doctors to look at the individual cells under a microscope.
How is a blood test carried out?
Most blood tests are taken from a vein, commonly from those around the elbow. The person drawing blood will wrap an elastic band around your upper arm to temporarily stop the flow of blood through the veins in your arm. This makes it easier to put the needle into a vein properly because the veins below the band get larger and do not collapse easily.
The site of the injection is then cleaned with alcohol and then a needle is inserted into the vein. More than one needle stick may be needed if the needle does not get placed correctly or if the vein cannot supply enough blood. When the needle is properly placed in the vein, a collection tube will be attached to the needle. Blood will flow into the collection tube.
When enough blood has been collected, the band around your arm will be removed. A gauze pad or cotton ball is placed over the puncture site as the needle is withdrawn. Pressure is applied to the puncture site for several minutes and then a small bandage is often placed over it.
How It Feels?
You may feel nothing at all from the needle puncture, or you may feel a brief sting or pinch as the needle goes through the skin. Some people feel a stinging pain while the needle is in the vein. However, many people do not feel any pain (or have only minor discomfort) once the needle is positioned in the vein. The amount of pain you feel depends on the skill of the person drawing the blood, the condition of your veins, and your sensitivity to pain.
Some people are very sensitive to needles and the sight of their own blood and may feel faint when a blood sample is taken. This is not uncommon and can be reduced by sitting or lying down while the sample is taken. If you feel faint or think that you might feel faint, immediately tell the person who is taking blood.
Risks
There is very little risk of complications from having blood drawn from a vein. You may develop a small bruise at the puncture site. You can reduce the risk of bruising by keeping pressure on the site for several minutes after the needle is withdrawn.
Rarely, the vein may become inflamed after the blood sample is taken. This condition is called phlebitis and is is usually treated with a warm compress applied several times daily.
Continued bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medications can also make bleeding more likely. If you have bleeding or clotting problems, or if you take blood-thinning medication, tell the person before your blood is drawn.
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