Which test is utilized to detect hidden blood in stool?

The guaiac test is specifically designed to detect hidden (occult) blood in the stool. This test is based on the reaction of guaiac, a chemical derived from the resin of certain trees, with hemoglobin from blood. During the test, a small stool sample is placed on a test card that contains guaiac. If blood is present, a color change will occur, indicating the presence of occult blood. This test is commonly used as a screening tool for conditions such as colorectal cancer, gastrointestinal bleeding, and other disorders involving the gastrointestinal tract.

In contrast, a stool culture is used to identify bacterial infections in the digestive tract but does not focus on detecting blood. A complete blood count measures various components of blood but doesn’t provide information about gastrointestinal bleeding or stool samples. A sigmoidoscopy is an invasive procedure used to visually examine the inside of the rectum and lower colon; while it can detect bleeding, it is not a test specifically designed for hidden blood in the stool like the guaiac test.