Fine Needle Aspiration Biopsy of the Thyroid

Fine needle aspiration biopsy (FNAB) of the thyroid is a powerful tool for the evaluation of thyroid nodules. It can also be used to evaluate enlarged lymph nodes in patients with a history of thyroid cancer. It can be performed safely in a few minutes in the outpatient setting.

Procedure

FNAB is performed in the office setting and does not require the patient to be given general anesthesia. Informed consent is obtained prior to the procedure being performed. If your clothes encroach upon your neck, you may be given a cape to wear so we have easy access to your thyroid (try to wear a shirt that will be open around the neck). Your neck will be cleaned with alcohol and an iodine solution to reduce the risk of infection. A local anesthetic (1% xylocaine) will be injected with a small needle into the skin over the thyroid nodule. This usually causes a stinging sensation, but numbs the area and makes the actual biopsy much more comfortable. Ultrasound imaging is used to localize the nodule and guide the insertion of a thin needle (usually 25 or 27 gauge needle which is smaller than the needle they draw your blood with) into the nodule. Most nodules require 4 passes of the needle to obtain an adequate sample of cells. The cells from the needle are placed on a microscope slide and sent out for pathologic examination. Following the procedure your neck will be cleaned and you will leave with a band-aid over the biopsy site.

Results and Follow-Up

It takes 1 week for the pathology results to return. We will ask you to return for follow-up 1 week after your FNAB so we can properly review these results with you, check on your progress following the procedure, answer your questions about the results of the FNAB, and formulate a plan for ongoing care of your thyroid nodule. Results are not given or reviewed over the telephone.

Biopsy results can be divided into 4 categories:

  1. BENIGN—Surgery is not usually recommended. Ongoing follow-up is needed since 1% of biopsies are false negative (ie-the benign nodule is an incorrect diagnosis and actually represents a thyroid cancer).
  2. SUSPICIOUS FOR CARCINOMA—Surgery is necessary.
  3. FOLLICULAR LESION—This type of pattern generally required surgery. The risk for cancer is approximately 1 in 5.
  4. NON-DIAGNOSTIC—The FNAB will need to be repeated (approximately 10% of FNAB procedures are non-diagnostic).

Risks and Complications of FNAB

  1. Infection at the biopsy site is an extremely rare possible complication.
  2. Pain—Most patients experience some mild discomfort during the injection of the anesthetic. Mild pain or pressure is usually present during the biopsy as well.
  3. Bleeding—Significant bleeding is a rare complication of FNAB, because we use very thin needles. However, rarely a patient may have bleeding into the nodule that was biopsied, and this may cause swelling of the nodule or pressure in the area of the neck where the biopsy was performed.
  4. Bruising—Most patients expience mild bruising at the biopsy site.
  5. Tenderness—The area that was biopsied may be tender for a few days following the procedure.

Tips for Your Procedure

  1. Do not take aspirin for 1 week prior to the FNAB (this helps to reduce bruising).
  2. Tell your doctor or provider if you take blood thinners (Coumadin, warfarin, Plavix, ASA).
  3. Wear a shirt with an open neck.
  4. Use an ice-pack on the neck if it is tender after the procedure.
  5. Tylenol may be used for any post-procedure discomfort.

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