[Purpose]
Thyroid puncture is often used for certain thyroid diseases that are difficult to diagnose after various tests. It is a routine test for goiter and thyroid nodular diseases, which helps to understand the nature of the pathology, determine the diagnosis and guide the treatment.
[Key points]
Thyroid puncture is divided into fine needle puncture and coarse needle puncture. Fine needle aspiration is preferred for the evaluation of thyroid nodules and has significant differential diagnostic significance for Hashimoto’s thyroiditis, subacute thyroiditis, and benign and malignant thyroid tumors. Diseases that can be diagnosed with certainty include: ① papillary thyroid carcinoma ② medullary thyroid carcinoma ③ undifferentiated carcinoma ④ Hashimoto’s thyroiditis ⑤ subacute thyroiditis ⑥ septic thyroiditis ⑦ cystic thyroid lesions ⑧ parathyroid cysts.
[Principle]
Fine needle aspiration is performed by puncturing a small needle into the lesion of the thyroid gland, extracting a small amount of cells, and understanding the nature of the cells through microscopy and making a diagnosis. With coarse needle aspiration, a very small amount of tissue is quickly excised from the thyroid gland with a trocar needle and examined by paraffin histology. However, thyroid puncture can sometimes result in false positives or false negatives and other misdiagnoses, because the accuracy of the diagnosis is closely related to the sampling site.
I. Indications for puncture
1 Diffuse thyroid disease with goiter
2 Thyroid nodules
3 Cystic lesions of the thyroid gland
4 Preoperative evaluation of superficial masses in other areas
II. Contraindications to puncture
The presence of heart disease, bleeding qualities, and definite hyperthyroidism.
[Step]
1. Laboratory tests and examinations ① Assessment of the patient’s general condition ② Assessment of the nature of the thyroid lesion ③ Routine determination of bleeding time, clotting time, platelet count.
2. Site and position Before puncture, the thyroid gland should be carefully palpated to determine the specific puncture site and direction of needle insertion. The patient is placed in a lying position, with the neck and shoulders elevated by pillows and the neck slightly posteriorly extended to fully expose the thyroid gland.
3. Biopsy tissue by coarse needle puncture
After local disinfection, towel laying, and local anesthesia, the 18G-Angiotech needle is inserted into the thyroid gland under ultrasound guidance to excite the cuff, and the striped tissue is removed from the blade needle core and placed in a 10% formalin solution bottle. The puncture is localized with compression for several minutes.
4. Fine needle puncture cytology examination
The operator stands on the side of the patient’s head, fixes the puncture site with the index and middle fingers of the left hand, punctures the 20 or 22 G-Angiotech needle into the thyroid gland under ultrasound guidance, pulls out the needle core, connects the puncture needle with a 5 ml syringe in the right hand, retains a small amount of air in the syringe, aspirates into a negative pressure state, then punctures back and forth rapidly in different directions 2-3 times, eliminates the negative pressure and pulls out the The needle is removed, the aspirate is discharged into the maintenance fluid, and the puncture is localized with compression for several minutes.
[Caution]
These two examination methods are easy to perform, cause little damage, and generally leave no scarring. Aspiration cytology can only show the cell morphology, but not the tissue structure; puncture biopsy has a higher diagnostic rate, but there is a possibility of bleeding and damage to the laryngeal nerve and trachea. In order to improve the accuracy of sampling and diagnosis the following issues should be noted.
(1) Smaller nodules (<1 cm) should be obtained by B-ultrasound-guided fine needle aspiration whenever possible. Large nodules over 4 cm should be taken from the peripheral area, as the central area is often organic and necrotic.
(2) Multi-site sampling is beneficial to improve the accuracy of diagnosis. Nowadays, it is generally recommended that 2-4 punctures should be performed for each nodule.
(3) If the nodule is progressively enlarged after the initial puncture or if the nodule does not shrink after T4 suppression therapy, it should be punctured again for cytological examination. If the diagnosis cannot be confirmed by re-puncture, a coarse needle biopsy should be performed for histological examination if the nodule is 2 cm in diameter.
(4) For cytologically diagnosed suspicious lesions and those with negative cytology but high clinical suspicion of malignancy, surgery should be performed.