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Needle aspiration biopsy (NAB), also known as fine needle aspiration cytology (FNAC), fine needle aspiration biopsy (FNAB) and fine needle aspiration (FNA), is a diagnostic procedure sometimes used to investigate superficial (just under the skin) lumps or masses. In this technique, a thin, hollow needle is inserted into the mass to extract cells that will be examined under a microscope. Fine needle aspiration biopsies are very safe, minor surgical procedures. Often, a major surgical (excisional or open) biopsy can be avoided by performing a needle aspiration biopsy instead.

illustration A needle aspiration biopsy is safer and less traumatic than an open surgical biopsy, and significant complications are usually rare, depending on the body site. Common complications include bruising and soreness. There is a risk, because the biopsy is very small (only a few cells), that the problematic cells will be missed, resulting in a false negative result. There is also a risk that the cells taken do not enable a definitive diagnosis.

Procedure: The skin above the area to be biopsied is swabbed with an antiseptic solution and draped with sterile surgical towels. The skin, underlying fat, and muscle may be numbed with a local anesthetic, although this is often not necessary with superficial masses. After locating the mass for biopsy, using x-rays or palpation, a special needle of very fine diameter is passed into the mass. The needle may be inserted and withdrawn several times. There are many reasons for this:

  • One needle may be used as a guide, with the other needles placed along it to achieve a more precise position.
  • Sometimes, several passes may be needed to obtain enough cells for the intricate tests which the cytopathologists perform.
  • When the mass is small, several passes may be necessary to position properly the needle tip.

After the needles are placed into the mass, cells are withdrawn by aspiration with a syringe and spread on a glass slide. The patient's vital signs are taken again, and the patient is removed to an observation area for about 3 to 5 hours.

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