Rh Typing test is performed on a sample of blood to measure the level of Rh Negativity in the blood.It is performed to confirm Rh Negative Pregnacy and also during the treatment and after the treatment of Rh Negative Pregnacy. Also known as Rh typing. Rh (Rhesus) factor is a protein that most people have on the surface of their red blood cells. It is important to know whether your blood is Rh positive or negative, If it is Rh – neagative you must be cautious during pregnancy.