To explore the learning curve of ultrasound-guided fine needle aspiration cytology (US-FNAC) without negative pressure and its influencing factors.

The operation time and clinical data of 135 patients who underwent US-FNAC by the same doctor at Shaanxi Provincial Tumor Hospital from June 2017 to June 2018 were collected. The patients were divided into nine groups (15 cases in each group) according to date of the operation (groups A-I). The operation time, complications and invalid procedures were compared among each group. According to the results, 135 patients were divided into three groups: anterior, middle and posterior (X, Y, and Z), and the differences between each two groups were compared and verified.

Statistical analysis was conducted in pairs from group A to group I, and it was found that there was statistical difference between groups A-D (P<0.05). There was a turning point between group D and group E, that was, there was no statistical difference between the two groups (P=0.561) as well as between groups E-I (P>0.05). Among groups X, Y, and Z, the operation time of group X was significantly longer than that in group Y and group Z [(6.23±1.38) min, (3.47±0.45) min, and (3.21±0.45) min, respectively; t=18.07, 23.15, P=0.000], although there was no significant difference between groups Y and Z (t=1.92, P=0.067). With the increase of operating cases, the incidence of complications and invalid procedures decreased gradually.

For ultrasonic doctors who perform US-FNAC, following the comprehensive cognition and scientific procedures of operation, 45 cases of US-FNAC are expected to pass through the turning point of the learning curve quickly and safely.