Which procedure is performed to obtain fluid from a joint?

The procedure designed to obtain fluid from a joint is known as arthrocentesis. This minimally invasive technique involves the insertion of a needle into the joint space to withdraw synovial fluid for diagnostic or therapeutic purposes. It is commonly used to analyze the fluid for conditions such as arthritis, infection, or gout, and can also relieve pressure in the joint by removing excess fluid.

In contrast, a biopsy generally involves the removal of tissue for examination under a microscope, rather than fluid. A laparotomy refers to a surgical procedure involving an incision into the abdominal cavity, which is unrelated to joints. Endoscopy is a technique that allows visualization and examination of internal organs using a flexible tube with a camera, but it does not pertain specifically to the extraction of fluid from a joint. Thus, arthrocentesis is the appropriate choice for obtaining fluid from a joint.