Why for pathological testing blood is drawn from left ring finger?
There is not real reason for this. It may be for less use of left hand but there isn't a real reason for this.
I have had multiple blood draws done every year since the middle 1990s and the blood has always been taken from veins in my forearm (sometimes left, sometimes right) near the elbow, never the hands or fingers. Diabetic blood sugar tests are often taken from the fingertips, but there is a tendency for many new test devices to get away from this and use the arm because the fingertips are more pain sensitive than the…
Say someone has a disease and they just got their blood drawn at the doctor's office. You are having your well check at the same time and you need blood drawn too. if they use the same needle and the other persons blood from the needle gets into your blood stream then you can get their disease. So it can be transmitted from a needle into your blood.