Methods: A retrospective analysis of 1,700 endobronchial ultrasound-guided transbronchial fine needle aspiration samples obtained from 822 patients (500 males, 322 females; mean age 56±13 years; range 16 to 83 years) was performed between March 2011 and March 2014 at our center. Variables potentially associated with sampling adequacy, such as all cytological materials and procedure notes (lymph node and/or lesion size, localization, needle pass number, and slide number) were examined.

Results: The overall specimen adequacy was 79.8%. The specimen adequacy was associated with needle pass number (p≤0.001). Adequacy rate was 66.9% for one needle pass and 85.8% for three needle passes. According to the sampling regions, adequacy rates showed a difference [69.2%-85.8%; (p≤0.005)]. In the multivariate logistic regression analysis of subcarinal (7) lymph node station, patient age (odds ratio, 0.983; 95% confidence interval, 0.966-1.000; p=0.049) and number of slides (odds ratio, 1.240; 95% confidence interval, 1.062-1.448; p=0.006) were independent determining factors of specimen adequacy. While independent determinants of specimen adequacy for the right paratracheal (4R) region were lymph node size (odds ratio, 1.486; 95% confidence interval, 0.973-2.268; p=0.067) and number of slides (odds ratio, 1.418; 95% confidence interval, 1.146-1.756; p=0.001), they were lymph node size (odds ratio, 1.594; 95% confidence interval, 0.960-2.645; p=0.071) and number of needle passes (odds ratio, 2.277; 95% confidence interval, 1.360-3.811; p=0.002) for the right interlobar (11R) region. Independent determinant of specimen adequacy for the left paratracheal (4L) lymph node station was the number of needle passes (odds ratio, 1.656; 95% confidence interval, 0.955-2.869; p=0.072).

Conclusion: During endobronchial ultrasound-guided transbronchial fine needle aspirations, particularly when rapid on site evaluation cannot be applied, consideration of factors affecting adequacy according to lymph node localizations may increase the chance for obtaining materials with suitable quality for cytologic evaluation.