: Macrophages, Body Fluid, Manual Count

: What Is Being Tested

: Macrophages are large white blood cells that engulf and remove debris, bacteria, and dead cells. When fluid collects in a body cavity (such as the pleural, peritoneal, or synovial space), a laboratory can examine a sample to see how many macrophages are present.

: How the Test Is Performed

: A sample of body fluid is collected by your healthcare provider, usually with a needle or during a procedure. In the laboratory, a trained technologist examines the fluid under a microscope and manually counts the macrophages in a defined area. This manual approach is often used when automated counters cannot reliably distinguish these cells.

: Why Your Provider Ordered It

: Your provider may order this test to help evaluate a buildup of fluid in a body cavity. The number and types of cells present can offer clues about whether the fluid is due to inflammation, infection, injury, or another underlying cause.

: What the Results Mean

: Results are reported as a count of macrophages in the fluid. The meaning depends on the type of fluid and the full pattern of cells seen, so results are interpreted together with other laboratory findings and your symptoms. Your provider will explain what your specific result indicates.