Venipuncture

Most of the time, blood is drawn from a vein located on the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). An elastic band is put around the upper arm to apply pressure to the area. This makes the vein below it swell with blood. A needle is inserted into the…

The steps you need to take before the test will depend on the kind of blood test you are having. Many tests do not require special preparation. In some cases, your health care provider will tell you if you need to stop taking any medicines before you have this test or if you need to be fasting. Do not stop or change…

You may feel slight pain or a sting when the needle is inserted. You may also feel some throbbing at the site after the blood is drawn.

Blood is made up of two parts: Fluid (plasma or serum) Cells Plasma is the fluid part of the blood in the bloodstream that contains substances such as glucose, electrolytes, proteins, and water. Serum is the fluid part that remains after the blood is allowed to clot in a test tube. Cells in the blood include red blood…

Normal results vary with the specific test.

Abnormal results vary with the specific test.

Dean AJ, Lee DC. Bedside laboratory and microbiologic procedures. In: Roberts JR, Custalow CB, Thomsen TW, eds. Roberts and Hedges' Clinical Procedures in Emergency Medicine and Acute Care . 7th ed. Philadelphia, PA: Elsevier; 2019:chap 67. Feirstein J. Venipuncture. In: Dehn R, Asprey D, eds. Essential Clinical…