What is guaiac test?

The guaiac test is a medical screening tool used to detect hidden (occult) blood in stool samples, which can indicate gastrointestinal bleeding. The test involves applying a stool sample to a special card containing guaiac resin, which changes color in the presence of hemoglobin. It is commonly used to help diagnose conditions such as colorectal cancer, ulcers, and other digestive disorders. Although it is a useful screening method, it may require follow-up testing for definitive diagnosis.