Stool for o/c test stands for stool for occult blood test. Occult blood test is a test that is used to detect hidden blood in the stool. Hidden blood can be a sign of a number of conditions, including colon cancer, ulcerative colitis, and Crohn's disease. The occult blood test is a simple and painless test that can be performed in a doctor's office or a laboratory. The test involves collecting a small sample of stool and testing it for the presence of blood. There are two types of occult blood tests: Guaiac-based test: This test uses a chemical called guaiac to detect the presence of blood. The stool sample is mixed with a guaiac reagent, and if blood is present, the reagent will turn a blue or green color. Immunochemical test: This test uses antibodies to detect the presence of blood. The stool sample is mixed with an antibody reagent, and if blood is present, the reagent will bind to the blood and cause a color change. The occult blood test is a sensitive test, but it is not specific. This means that a positive test result can be caused by a number of conditions, not just colon cancer. If you have a positive occult blood test result, your doctor will likely order further testing, such as a colonoscopy, to determine the cause of the blood.