Comparison of three specimen collection techniques in tissue coagulum clot-based cell block preparation of endobronchial ultrasound-guided transbronchial needle aspiration

Objectives

The performance of cell blocks (CBs) can vary significantly depending on the specimen collection and processing techniques used. This study compared the efficiency of three distinct specimen collection methods for endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) samples.

Materials and methods

From June 2021 to June 2023, the study involved 1450 patients who underwent EBUS-TBNA, resulting in the sampling of 1941 lesions. For these samples, three distinct specimen processing methods were employed to prepare tissue coagulum clot-based CBs. Specifically, the filter paper method was employed in 470 cases (yielding 626 samples), the centrifugation method in 500 cases (yielding 673 samples), and the funnel filtration method in 480 cases (yielding 642 samples).

Results

Out of these 1941 samples, the diagnostic yield for samples obtained using filter paper, centrifugation, and funnel filtration methods was 84.7 %, 87.7 %, and 92.5 %, respectively. In the subgroup of patients diagnosed with non-small cell lung cancer, the adequacy rate for molecular testing in samples processed through filter paper, centrifugation, and funnel filtration methods was 57.7 %, 82.0 %, and 88.3 %, respectively. In the centrifugation group, the combination of the CBs and cell pellet achieved an adequacy rate of 96.5 %.

Discussion

The cellular yield of CBs from EBUS-TBNA was significantly enhanced using centrifugation and funnel filtration methods. The funnel filtration method offered a more convenient and cost-effective approach, reducing cellular loss due to sample dispersion in the fixative medium. The use of the centrifugation method to prepare CBs, along with the retrieval of cell pellets from the residual fixative medium, can maximize the specimen adequacy rate for molecular testing.