Read on to learn more about fine needle aspiration biopsy (FNAB) of the thyroid.
The thyroid gland is located in the lower part of the neck, below Adam's apple. The gland wraps around the windpipe (trachea) and has a shape that is similar to a butterfly - formed by two wings (lobes) and attached by a middle part (isthmus).
It is responsible for producing thyroid hormone, which is an important hormone that stimulates the metabolism of the body.
Most of the thyroid nodules are harmless growths, known as adenomas, and are contained within a capsule, but a doctor may recommend fine needle aspiration biopsy of the thyroid: to make a diagnosis of a thyroid nodule, to help select therapy for a thyroid nodule, to drain a cyst that may be causing pain; or to inject a medication to shrink a recurrent cyst.
First, the patient will undergo a complete medical history and physical examination and the doctor will look for general symptoms of thyroid disease in addition to other illnesses.
A few factors that increase the suspicion of malignancy are:
- Age (patients less than 30 years and greater than 60 years of age)
- Symptoms like difficulty swallowing or hoarseness
- Hard, fixed nodule
- Surrounding enlarged lymph nodes
- History of head and neck irradiation
- Previous history of thyroid cancer in the family
Fine needle aspiration biopsy can be performed in the doctor’s office sometimes with ultrasound to help guide the biopsy. The patient lies down and the neck is exposed.
The doctor drapes the area around the neck and cleans the neck off, usually with iodine and some doctors may choose to inject a local anesthetic but since the needle used for fine needle aspiration biopsy is so fine, most doctors do not use anesthetic.
Then a small, fine-gauge needle is inserted into the nodule and the patient holds his breath while the needle is rocked gently to obtain as much tissue as possible because it minimizes movement of the structures in the neck.
The needle is then withdrawn and pressure is applied over the thyroid area to minimize bleeding. The entire procedure usually takes less than 20 minutes.
After the procedure, most patients notice very little bleeding or swelling and discomfort in the area for a few hours after the biopsy. The complications of FNAB are very rare but they can include bleeding, infection, and cyst formation.
The tissue obtained from the procedure is prepared onto glass slides and sent to the pathologist for classifications as benign, malignant, suspicious or indeterminate. The result is sent to the doctor's office, usually within one week.