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.
Where are the heart and blood vessels found? The heart is a fist-sized organ which lies within the chest behind the breastbone (sternum). The heart sits on the main muscle of breathing (the diaphragm), which is found beneath the lungs.