Blood Collection: Venipuncture

• • clinical laboratories, analyze Venous blood samples, obtain via phlebotomy
• • To collect venous blood, the phlebotomist pierces the vein with a hypodermic needle and draws the blood into a syringe or uses a commercially available venous blood collection apparatus, such as the vacuum collection system.
• A venipuncture's objective is to obtain a blood sample from the correct patient into the correct tube with the least amount of trauma or stasis possible.
• Venipuncture is a term that refers to the process of collecting or drawing blood crume i in for ma purpose of administering intravenous therapy or sampling venous blood.
• Blood analysis is one of the most important diagnostic tools available to linicians within the healthcare.
• Venipuncture has two commonly performed methods: syringe method and evacuated tube method. The syringe method is an open system used when small and fragile veins are involved. The vacuum system comprises a double-pointed needle, a plastic holder or adapter, and a series of vacuum tubes with various colored rubber stoppers. The colors denote the additive type.
• Both ends of the vacuum collection needle are pointed, with one being shorter than the other. The needles long end is used to insert it into the vein; the shorter end is used to pierce the vacuum tubes rubber stopper and is typically covered in a rubber sheath. By preventing blood leakage as tubes are change, the sheath enables the needle to draw multiple tubes of blood; this is referred to as a multi-draw or multi-sample needle.
• Needles come in a variety of sizes; the size chosen is determined by the length and gauge of the needle that will enter the vein. Blood collection needles are available in lengths, ranging from one to twelve inches. For routine venipuncture, one-inch needles are used; 12-inch needles are used for patients with extremely deep veins.
• lumen, alternatively called the bore, is the circular hollow space inside the needle.
• The gauge number is greater; the lumen is smaller.
• The most frequently used needle gauges used for phlebotomy are: 20g (yellow top), 21g (green top), and 22g (black top).
• The bevel is the angled opening at the needle's tip.
• Blood vacuum collection tubes áre glass or plastic tubes that are sealed with rubber stoppers to create a partial vacuum inside.
• Inside the tube, the air pressure is negative, lower than in the surrounding environment.
• The different colors of the tube stoppers indicate the type of additive contained within. The most frequently used additive is an anticoagulant, which prevents blood clotting. The clear fluid in an anticoagulated specimen is called plasma. Without an anticoagulant, a specimen will clot, and the liquid portion is called serum. Other additives serve other functions. Some tubes may also contain a polymer gel which will create a physical barrier between the liquid portion of the sample and the cellular elements during centrifugation.
• phlebotomist fills several vacuum collection tubes, each with a different colored stopper appropriate for the test ordered. This is referred to as multiple drawing or multiple-drawing.
• The use of a tourniquet aids in the selection of the optimal site for venipuncture.
• The tourniquet should not be left in place for more than I minute as this can alter the blood's composition, affecting the results of numerous laboratory tests.
• Venipuncture should be performed on the forearm's large veins, which are the median cubital, cephalic, or basilic veins. The basilic vein runs parallel to the forearm's anterior surface and is connected to the cephalic vein by the median cubital vein.