Fine-Needle Aspiration Samples

The fine-needle aspiration biopsy (FNA) is a minimally invasive, cost-effective, highly accurate, rapid-turnaround diagnostic procedure to evaluate palpable or deep-seated masses.

Instructions for clinicians performing FNAs of of superficial masses

We highly recommend that an experienced physician perform FNA of the superficial masses. FNA procedure performed by inexperienced physician often yields a sub-optimal or non-diagnostic sample, and prompting additional diagnostic procedures with more complications. Our staff pathologists are experienced in FNA and available to perform FNA from patients referred to our FNA clinic at UC Davis Cancer Center as well as within UC Davis Medical Center.

Clinicians experienced in performing FNA should follow the recommendation/procedures below.


We recommend 22 or 25 gauge, 1.5 inch long, disposable needles, 10 cc disposable plastic syringes with Luer-Lok tip, and a syringe holder, or a 3 cc syringe without the syringe holder. Clean glass slides with a frosted end should be used. The patient's name and medical record number should be written with a pencil on the frosted end. If more than one site is aspirated, please indicate the site/source on the frosted end of the slide. Please submit aspirations from separate sites as separate specimens.


  • After the skin has been cleaned with alcohol, and ifdesired, anesthetized with a subcutaneous lidocaine injection, the mass should be stabilized with your non-dominant hand between your thumb and forefinger.
  • Introduce the needle through the skin and make sure that the plunger of the syringe is at the "0" cc mark.
  • Advance the needle into the mass.
  • When the needle has entered the lesion, apply suction slowly by pulling back the plunger of the syringe as much as possible.
  • Move the needle back and forth within the mass several times while maintaining the suction and taking care not to remove the tip of the needle from the mass.
  • Release the plunger, and then withdraw the needle from the patient. Note: It is a common mistake to withdraw the needle from the mass while still applying suction. This will cause all the aspirated material to flow into the barrel of the syringe, from where it is extremely difficult to extract. If this happens, the entire procedure should be repeated using a new syringe and needle.
  • Apply pressure at the site of aspiration. (This is extremely important particularly when aspirating breast or thyroid masses.)


The aspirated material clots very quickly, and there should be no delay in preparation of the smears.

  • Detach the needle from the syringe.
  • Fill the syringe with air.
  • Reattach the needle to the syringe.
  • Place the bevel of the needle against the glass slide and squirt the contents of the needle onto the slide.
  • Using a clean glass slide or a coverslip, smear the cellular material as if t were a blood smear.
  • Immediately after preparation of the smears drop 1 or 2 smears into 95% alcohol, or immediately spray with a cytofixative (Spray-Cyte).
  • Allow the rest of the smears to air dry.

The entire needle aspiration procedure should be repeated at least three times in order to obtain an adequate sample.


The aspirated material can be submitted by thoroughly rinsing the needle contents into cytofixative, or into sterile RPMI. Both fixatives are available from the cytology laboratory. In case RPMI is used as a collection medium, the material should be immediately transported to the Cytology Laboratory, or if collected after hours, refrigerated until the next courier pickup. For offsite PCN locations, the needles can be rinsed into a Surepath Pap Test vial and submitted to the laboratory with the appropriate laboratory requisition and clinical information.

Completing the FNA Specimen Requistion

In addition to the clinical history and clinical impression, be sure to describe whether the mass is fixed or mobile, the appearance of the overlying skin, the resistance of the tissue to the aspirating needle, and whether you felt that you adequately stabilized and penetrated the mass.


Fine-needle aspiration biopsies of deep visceral or non-palpable masses

Deep or non-palpable masses are sampled under image guidance, such as CT, ultrasound, or fluoroscopy, and are scheduled through the Department of Radiology. The FNA service should be notified so that Cytology staff can be present to prepare the smears and assess the adequacy of the aspirated material. During regular laboratory operating hours, please call (916) 734-3031. Outside of regular operating hours, please contact the AP pathologist or resident on call by contacting the hospital operator.