Ultrasound Guided FNA (Fine Needle Aspiration) of Thyroid Nodules

FNA stands for fine needle aspirate. A small sample of cells are taken from the thyroid nodule with a needle. The cells are sent to the pathology laboratory, and the pathologist determines the diagnosis. Not all thyroid nodules require FNA.

The American College of Radiologists recommend FNA for:

  1. Tirads 3 nodules greater than or equal to 2.5cm.
  2. Tirads 4 nodules greater than or equal to 1.5cm. 
  3. Tirads 5 nodules greater than or equal to 1cm.

The Tirads classification of thyroid nodules is based on the ultrasound features of the nodule (see section on thyroid ultrasound).  

Patients with both thyroid nodules and abnormal lymph nodes require FNA of one of the abnormal lymph nodes.

Several studies have shown that ultrasound guided FNA is more accurate than freehand (without ultrasound guidance) FNA. Therefore, it is recommended that fine needle aspiration (FNA) of thyroid nodules is done under ultrasound guidance.

FNA cytology results are classified according to the Bethesda system as follows:

Bethesda   Description  Risk of malignancy 
1  Non diagnostic  12% 
2  Benign  2% 
3  Atypia of undetermined significance (AUS)  16% 
4  Follicular neoplasm  23% 
5  Suspicious for malignancy  65% 
6  Malignant  94% 

Dr Hall performs all of his thyroid FNA under ultrasound guidance and local anaesthesia. He uses an ultrasound machine to ensure the needle goes directly into the thyroid nodule. After the procedure, a band aid is placed over the area where the needle went. You can return to work the same day. 

Usually, the pathologist sends a typed signed report to Dr Hall about one to two weeks after the procedure. Occasionally it may take the pathologist longer to issue a report either because of the complexity of your case or because of high workloads. Dr Hall will contact you by phone or text once he receives the pathologist’s report. He will advise you what the next step is to manage your condition.

 

References:

  1. Ali SZ, et al. Thyroid 2023; 33: 1039-1044.  The 2023 Bethesda System for Reporting Thyroid Cytopathology.  
  2. Tessler FN, Middleton WD, Grant EG, Hoang JK, Berland LL, et al. ACR Thyroid Imaging, Reporting and Data System (TI-RADS): White Paper of the ACR TI-RADS Committee. (2017) Journal of the American College of Radiology : JACR. 14 (5): 587-595. doi:10.1016/j.jacr.2017.01.046 - Pubmed