How is occult GI bleeding usually detected?
- Occult GI bleeding is typically detected by obtaining a stool sample, smearing the stool sample on a guaiac-impregnated card, and applying a reagent solution to the card.
- A positive test is indicated by change in the color of the impregnated card from colorless to bright blue because of the presence of peroxidase (or pseudoperoxidase) in the stool.
- As little as 2 to 5 mL of blood per rectum per day can produce a positive guaiac test.
