[Solved] What is the difference between fixed costs and variable costs? Occult Blood: Refers to the presence of blood in the feces that is not visible to the naked eye, usually detected by chemical tests. Menstrual Cycle: The regular natural change that occurs in the female reproductive system, marking the preparation for potential pregnancy. Throat Cultures: A test involving the collection of a sample from the back of the throat using a swab to identify bacteria or viruses causing infections such as strep throat. Tongue Blade: A medical tool used to depress the tongue to allow for examination of the mouth and throat.