A fine needle aspiration (FNA) removes some fluid or cells from a breast lump, either a cyst or a solid mass. The FNA needle is very fine, about 0.7–1mm in diameter, similar to that used for drawing blood samples. Local anaesthetic is usually given to help reduce the pain. Ultrasound scan is then used to locate the lump and guide the placement of the needle into the lump. The doctor may have to repeat the aspiration several times in order to obtain adequate cell samples for examination. The whole procedure usually takes around 15–20 minutes.
FNA may be chosen as the diagnostic test for women with a lump that is thought to be benign (non-cancerous) or when the lump is fluid-filled, i.e. a breast cyst. In these situations, FNA is preferred to a core biopsy because it is less invasive. It serves to confirm the diagnosis of a benign condition. Some breast lesions are cysts filled with fluid, and in this situation, the FNA can have an additional benefit of relieving the symptoms after withdrawing the fluid from the breast cysts.
If the lump is solid, and if there is any concern about the nature of the lump, a core needle biopsy should be considered because it will be more accurate in making a diagnosis.