Definition: Retrojection is a medical term that describes the process by which the body redirects or retracts an internal fluid, such as blood, back into the circulatory system. This can occur when there is an obstruction in the blood vessels, such as in a heart condition or a pulmonary artery disease. In this context, retrojections refer to the movement of blood from one part of the body (the "source") into another (the "destination"). Retrojection occurs when the blood vessel that supplies the