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.
The heart is located slightly to the left side of your chest. It is a powerful organ made of cardiac muscle. Unlike other muscle in the body, it never tires. Its function is to pump blood around the body, and to do this is contracts and relaxes about 70 times a minute.