Venipuncture, also known as blood sampling, involves using a needle to access a vein and draw a small amount of blood for testing. Most adults have blood drawn from the inside of the elbow using a vacuum tube, while children may have blood drawn from the hand or foot. The amount of blood taken is usually small, and multiple tubes may be used for multiple tests. Venipuncture is also used to start IV lines for administering fluids or medications.
Venipuncture is the method by which blood is drawn in most cases and can also be called phlebotomy or blood sampling. It refers to using a needle to pierce the skin and access a vein so that a small amount of blood can be removed for various studies. Most people will experience a venipuncture at some point in their lives, either to test for disease or to evaluate for various elements in the blood that could indicate poor health.
Most adults will have their blood drawn from the inside of the elbow, where the phlebotomist or other medical technician or specialist can access the median cubital vein. The standard method is to insert a needle through the skin and into this vein, which can first be slightly enlarged using a tourniquet for one minute. The blood is then usually drawn using a special vacuum tube which will hold the blood until various tests are performed on it. Because people may require several tests from a single venipuncture, more than one vacuum tube can be used to collect blood, but this does not tend to require more than one puncture. In rare cases, a syringe method is used instead to collect blood, but the vast majority of venipuncture types use the vacuum tube.
Young children may have blood drawn from several areas, including the hand or foot. Although this is more painful, it is usually easier to access the superficial veins on infants and children from these areas. Patients or their parents may sometimes have a preference here, and moms or dads might instead advocate a venipuncture performed on the median cubital vein, especially if a child is more than a couple months old.
To the person undergoing a blood draw, particularly if they have a fear of needles or are alarmed at the sight of blood, the multiple tubes used to collect blood may seem to collect a lot of blood. In reality, the samples taken tend to be very small, although they may not appear to be. A single vial might hold 5 milliliters, which equals one teaspoon. This should be compared to the amount of blood a person could voluntarily donate. It takes about 29 milliliters to make up one ounce, and the standard blood donation is about 16 ounces or 473.2 mL. While that may seem like a lot, even if multiple vials are used, usually no more than a gram of blood is lost—one sixteenth of a voluntary blood donation.
Venipuncture also occurs when people have started IV (intravenous) lines. In most cases, it is necessary to pierce the skin and access a vein so that intravenous fluids or medicines can be given. The procedure for this is slightly different and can be more complex. However, when an IV line is present, blood draws can occur through this open access, rather than having to perform additional procedures, which can be useful in hospital settings where blood tests may be required frequently.
Protect your devices with Threat Protection by NordVPN
