Learning curve of thyroid fine-needle aspiration biopsy

Background Fine-needle aspiration biopsy (FNAB) is the reference procedure for thyroid nodule evaluation. Its main limitations are inadequate samples, which should be less than 20%. Objective To analyze the learning curve of the procedure by comparing the results of a non-experienced endocrinologist (endocrinologist 2) to those of an experienced one (endocrinologist 1). Material and methods Sixty FNABs were analyzed from February to June 2016. Each endocrinologist made 2 punctures of every nodule in a random order. This order and the professional making every puncture were unknown to the pathologist who examined the samples. Results Endocrinologist 1 had a higher percentage of diagnoses than endocrinologist 2 (82% vs. 72%, p = 0.015). In the first 20 FNABs, the difference between both physicians was remarkable and statistically significant (80% vs. 50%, p = 0.047). In the following 20 FNABs, the difference narrowed and was not statistically significant (90% vs. 65%, p = 0.058). In the final 20 FNABs, the difference was minimal and not statistically significant (75% vs. 70%, p = 0.723). Conclusions The learning curve of ultrasound-guided FNAB may be completed in a suitable environment by performing it at least 60 times. Although the guidelines recommend at least 3 punctures per nodule, 2 are enough to achieve an accurate percentage of diagnoses.