Final answer:
A stool guaiac test is used to detect hidden blood in a stool sample. It is a colorimetric test where a color change indicates the presence of blood, which could signify various health issues. Other tests like stool culture or GGT are not used for detecting occult blood in stool. Therefore, correct option is a.
Step-by-step explanation:
The laboratory test that can detect hidden blood in a stool sample is known as a stool guaiac test. This test is used to identify occult blood that is not visible to the eye.
The presence of blood can be an indication of various conditions, including gastrointestinal bleeding, certain infections, or colorectal cancer.
The test involves applying a small sample of stool onto a guaiac paper and then adding a developing solution that will cause a color change if blood is present.
Other tests mentioned, such as stool culture and detection of bacteria in stool samples, are used to identify infectious organisms that might cause symptoms like diarrhea.
Total bilirubin and GGT (Gamma-glutamyl transpeptidase) are tests that are commonly included in liver function tests and would not be used for the direct detection of blood in stool samples.