The two most important ancillary tests for the differentiation of benign and malignant thyroid nodules are thyroid ultrasound and fine needle aspiration biopsy (FNA). In 1982, a foreign study showed that only 14% of preoperative thyroid nodules not clearly diagnosed by FNA were diagnosed as malignant thyroid tumors after surgery, while a 2007 study confirmed the diagnosis of malignant thyroid tumors. A 2007 study confirmed the need for preoperative FNA of suspicious thyroid nodules, and as of 2007, the percentage of malignant nodules with preoperative FNA exceeded 50% (with the development of ultrasound technology, the accuracy of ultrasound diagnosis today has improved significantly compared to the period of these two studies). Preoperative thyroid biopsy consists of two main types of fine-needle aspiration (FNA) and coarse-needle aspiration (CNB). FNA is widely used because it does not require local anesthesia, is well tolerated by the patient, is relatively easy to perform, is more lenient on nodal requirements, and is more cost-effective. However, even though FNA has many advantages as described above, it still has its own limitations. The main shortcoming is that it is relatively easy to arrive at an unclear diagnosis. As the name implies, fine needle aspiration has a thinner needle, which is less invasive and uncomfortable and more tolerable to the patient, but it is also because of the thinner needle that no tissue mass can be obtained but only cells, which limits the reliability of the FNA diagnosis. Failure to diagnose can be caused by an insufficient number of cells in the puncture aspirate, more blood, thicker smears, or untimely smears, and this can occur in 2-20% of cases. Another condition that cannot be definitively diagnosed is AUS, which occurs in 3-6% of cases. For example, follicular adenocarcinoma of the thyroid requires clear evidence of vascular or envelope invasion to confirm the diagnosis, which is not possible with cytologic diagnosis, and CNB aspiration to obtain a tissue mass may compensate for this shortcoming. The guidelines recommend that patients diagnosed with nondiagnostic and AUS be followed up with ultrasound, repeat FNA (rFNA), or surgery, as appropriate. More recent studies have compared the sensitivity and accuracy of FNA/rFNA and CNB for the diagnosis of thyroid nodules, both in China and abroad, and almost all have produced similar results: CNB has a higher accuracy than FNA/rFNA and a higher sensitivity for malignant nodules. However, the application of CNB is significantly limited because it requires local anesthesia, is relatively more invasive, is less well tolerated by patients, is more complex, has a longer culture period, and is more demanding on nodes. Based on these results, FNA is still the first-line biopsy method for preoperative diagnosis of thyroid nodules, and CNB is a better diagnostic tool compared to rFNA for patients in whom FNA has not been definitively diagnosed. Patients often ask about complications after FNA and CNB operations in the outpatient clinic and on the ward. There are only occasional reports in the literature of individual cases of intra-thyroidal bleeding urgently requiring surgery or metastasis from the punctal tract after FNA/CNB, and no reports in the literature of bulk metastasis from the punctal tract after the operation have been found. The majority of patients have not experienced any complications after biopsy or have only acceptable paracentesis hematoma formation, so the above two biopsies are relatively safe and reliable.