Flow is a laboratory test that is used to examine the number and type of specialized immune cells in a tissue sample. Other names for this test are flow cytometry and flow immunophenotyping. Unlike other types of laboratory tests, this test can examine millions of individual cells very quickly and collect information about each cell. The information collected includes the size and shape of the cell and the types of proteins being made by the cell. This test can also tell if a cell is healthy or if it is dying.
Flow is often performed on cells from from the blood or an enlarged lymph node where it is used to diagnose cancers of immune cells, such as leukemia or lymphoma. It is also helpful in determining if the changes in a lymph node are reactive and non-cancerous.