1 A blood clot that forms inside one of your veins or arteries is called a thrombus. A thrombus may also form in your heart.  A thrombus that breaks loose and travels from one location in the body to another is called an embolus.
The kidneys. The kidneys do vital work in the body filtering blood removing waste into urine, and balancing electrolyte levels. Our blood in our bodies passes through the kidneys several times a day. The kidneys are located at the back of the abdomen. Each kidney is about the size of a fist - 10-12.5cm long.
What is Kidney Pain? Kidney pain is a term often used to describe a lower back pain that is more lateral (towards the side) or around the flanks. However the kidneys, despite popular belief, are not located in the lower parts of the abdomen. The kidneys lies just below the diaphragm on either side towards the back of the abdomen in an area known as the retroperitoneal cavity. Back pain is by far the most common cause of what is termed kidney pain.