Carcinoembryonic antigen test is usually done by drawing blood and the result is usually available on the same day. The normal value of carcinoembryonic antigen is <5μg/L. When carcinoembryonic antigen is elevated, it may be caused by colon cancer, rectal cancer, lung cancer, breast cancer, gastric cancer, pancreatic cancer, etc. In addition, some inflammatory diseases may also have elevated carcinoembryonic antigen, for example, emphysema, bronchial asthma, colitis, pancreatitis and other diseases. Elevated carcinoembryonic antigen needs to be diagnosed together with clinical symptoms and imaging examination, for example, gastric cancer patients may have nausea and vomiting, vomiting blood, etc., and be diagnosed together with gastroscopy and pathological biopsy.