DefinitionCarcinoembryonic antigen (CEA) is a protein normally found in the tissue of a developing baby in the womb. Blood levels of this protein disappear or become very low after birth. In adults, an abnormal amount of CEA may be a sign of cancer.A blood test can be done to measure the amount of CEA in your blood.Alternative NamesCarcinoembryonic antigenHow the test is performedBlood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic. An elastic band is placed around the upper arm to apply pressure and cause the vein to swell with blood.A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the bloo