Getting Your First Blood Test – It’s Nothing to Worry About
First the care giver identifies the vein from where blood is to be drawn. A tourniquet / tight band is placed around the upper arm to fill the vein with blood, the area is sterilized with antiseptic and blood is drawn through a needle connected to a syringe or blood sample bottles.
In cases where oxygen levels in blood need to be determined, blood is taken from an artery at the wrist. This is usually done at medical facilities like hospitals.
Another example is testing for glucose; only a very small amount of blood is required to get accurate results. So typically a tiny drop of blood is taken from the fingertip. These days most people who suffer from diabetes have home blood test kits to monitor their blood sugar levels periodically.