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 in the thoracic cavity, in the portion of the chest known as the mediastenum-the region between the pleural sacs and containing all the thoracic viscera except the lungs.The pericardium is the thin sac or membrane which contains the heart and the roots of the great blood vessels.hen you refer to a body cavity, you would say the heart lies in the thorax or thoracic cavity. Within that cavity, it lies within the mediastenum, and is surrounded by the pericardium.