What is fine-needle aspiration?

Fine-needle aspiration is a method of collecting cells from the breast, liver, mouth, neck, lymph nodes, genitals, respiratory tract, or thyroid to look for signs of cancer, infection, or other conditions. A doctor inserts a thin needle into a lump and withdraws a sample of cells or fluid. The material is then examined under a microscope.

Fine-needle aspiration may be the only test you need to find out whether a lump is cancerous. But in some cases you may have another procedure, such as a core needle biopsy or an open biopsy. In a core needle biopsy, you will have local anesthetic to numb the area. The doctor places the core needle-which is larger than the needle used in an aspiration-into the lump. Then he or she takes out a thin section of tissue (about the size of a pencil lead), rather than a few cells. In an open biopsy, a doctor uses a surgical knife to remove a sample of tissue. An open biopsy may be done in the operating room, with or without a general anesthetic.

How is a fine-needle aspiration done?

Your doctor will wipe the area with rubbing alcohol or iodine. In most cases, you will receive an injection of local anesthetic to numb the area of your breast where the needle will be inserted. Your doctor will hold the lump steady with one hand and insert a thin needle (attached to a syringe) into the lump. He or she may move the needle in and out of the area to make sure to get enough tissue or fluid for the biopsy. Then he or she pulls on the plunger of the syringe to remove the tissue or fluid. The process takes a few seconds to a few minutes.

If the doctor cannot easily feel the mass, you may have an imaging test, such as a CT scan, ultrasound test, magnetic resonance imaging (MRI), or mammography to see where to put the needle. In this case, a doctor known as a radiologist may do the aspiration. If the lump is a cyst, the fluid is removed, and the lump usually goes away.

How will it feel?

If you receive a local anesthetic, you may feel a brief sting when it is injected. You also may feel some pressure when the biopsy needle is inserted. The amount of discomfort will depend on how much pain you feel from needles, the part of your body involved, and the skill of the doctor. The site of the fine-needle aspiration may be sore for a couple of days, and you may have a bruise. You should be able to return to work the same day or the next day.

What happens afterward?

Your doctor will apply pressure to the aspiration site to prevent bleeding and put an adhesive bandage on it. He or she may recommend that you take a mild pain reliever, such as acetaminophen (Tylenol) or ibuprofen (Advil), if you have discomfort when you get home. Keep the area dry for 24 hours.

Contact your doctor if you have bleeding, redness, swelling, or a fever of more than 100.5F over the next couple of days.