The indirect Coombs' test is done on a sample of the liquid part of the blood. It detects antibodies that are present in the bloodstream and could bind to certain red blood cells and destroy them. A Coombs' test involves taking a sample of blood.
It is placed in the middle of the chest or thoracic cavity (middle mediastinum), posterior to the body of sternum and the second to sixth costal cartilages and anterior to the fifth to the eighth thoracic vertebrae.
In humans, the heart is a fist-sized muscle located slightly to the left of center in the chest. It acts as an engine for the circulatory system, pumping blood through the blood vessels. It will beat approximately three billion times in an average human lifespan.