Background: Although the pooled sensitivity of endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) using a convex scanning ultrasound bronchoscope is equivalent to the gold standard of mediastinoscopy, diagnosis cannot be obtained in a small number of patients with poor cellularity. The method described was investigated with the aim of avoiding puncturing the cartilage and enabling reliable tissue harvesting, as this can be expected to improve diagnostic yield.
Methods: Outer sheath method (OSM): While pressing the outer sheath (OS) of the puncture needle gently against the bronchial wall, the hyperechoic line appeared on surface of the bronchial wall on EBUS image. Then pulling and pushing the entire bronchoscope, the tip of OS moved to the epithelium above the bronchial cartilage while detecting the best position for puncturing on the EBUS images simultaneously. The bronchoscopist could visualize the cartilage moving longitudinally on EBUS image. The movement of the cartilage was stopped when the tip of the OS was caught in a concavity between 2 rings of cartilage. Group A consisted of 169 patients who underwent EBUS-TBNA before the introduction of OSM, and group B consisted of 169 patients who underwent EBUS-TBNA after the introduction of OSM. These 2 groups were compared with to investigate the usefulness of OSM.
Results: Adding this operation enabled a suitable puncture site to be identified, significantly improving diagnostic yield from 92.7% (group A) to 98.2% (group B).
Conclusions: This method was regarded as useful for improving diagnostic yield by enabling the selection of a puncture site between rings of cartilage during EBUS-TBNA.