What procedure does Aspiration describe in a medical context?

Aspiration in a medical context refers to the procedure of withdrawing gas, fluids, and semi-solids from body cavities. This is commonly performed to relieve pressure from excess fluid, to gather samples for diagnostic purposes, or to remove unwanted substances from the body. For example, a physician may use aspiration to extract synovial fluid from a joint or to clear mucus from the respiratory tract.

In this context, the withdrawal of these substances is generally done using a syringe or a similar instrument, making it a critical procedure in various medical scenarios, such as in the treatment of effusions or in certain diagnostic tests. The other options provided pertain to different medical procedures: injections deal with delivering substances into the body, infusion involves administrating nutrients directly into the bloodstream, and biopsy refers to the surgical removal of tissue samples for examination. Each of these processes serves distinct purposes within the medical field, but aspiration specifically pertains to the withdrawal of fluids or semi-solids from body cavities.