FNA procedure
THYROID, -20
FNAs were performed under ultrasound (US) guidance by the same experienced operator. For patients with multiple nodules, FNA was performed on suspicious nodules, otherwise, the largest nodule was selected for sampling. For patients with mixed cystic-solid nodules, FNA was performed from the solid component. An US scanner (M9, Mindray, Shenzhen, China) was used for US with a 7.5-15 MHz linear array transducer. The medical record report contained the number, location, size, echogenicity, composition, vascularity, calcifications, depth, and Thyroid Imaging Reporting and Data System (TIRADS) categories of the punctured nodules. The passes were performed using a 25-gauge disposable puncture needle with a stylet (CCZA, Leapmed, Suzhou, China) without syringes. The stylet in the needle was kept during the puncture for S+ passes and removed before S- passes.The S+ pass was performed as follows: The patient was placed in a supine position with the neck slightly extended. The patient underwent local anesthesia using 0.1-0.3 ml of 2% lidocaine, and the skin was disinfected with iodophor. The stylet was removed after the needle tip puncture was put into the nodule under ultrasound guidance. The needle was pulled out when the needle was cut back and forth 15-20 times within the nodule or when the sample material was seen in the hub. Suction was not used in the process. The material in the needle lumen was expelled onto one clean glass slide using a 5 ml air-filled syringe after each pass. All the steps were the same for the S+ and S- pass, except for the stylet removal step that was avoided in S- pass.One slide specimen was made for each pass smear, and these slides were labeled as slides A1, B1, A2, and B2 in the order of pass. Sometimes slides A (A1 and A2) were two S+ specimens or two S- specimens since the choice of - the first pass was random to avoid bias of the pathologist. No on-site assessment was performed, where the specimens were air-dried, fixed in 95% alcohol, and stained with hematoxylin and eosin.