Final answer:
If you are looking for fat or urobilinogen in a stool sample, it needs to be refrigerated for several days ideally at least 7.
Step-by-step explanation:
If you are looking for either fat or urobilinogen in a stool sample, it needs to be refrigerated for several days ideally at least 7. This is because microscopic examination of stool over several days allows for better analysis of these substances. Some serologic testing is also available to detect these substances.