Factors Affecting the Diagnostic Yield of Endobronchial Ultrasonography with a Guide Sheath Transbronchial Biopsy

Abstract

Background. Previous studies demonstrated the usefulness of endobronchial ultrasonography with a guide sheath transbronchial biopsy (EBUS-GS-TBB) in the diagnosis of peripheral pulmonary lesions. However, factors affecting the diagnostic yield of EBUS-GS-TBB have not been fully investigated. Objective. We performed a retrospective analysis to identify factors affecting the diagnostic yield of EBUS-GS-TBB in peripheral pulmonary lesions. Methods. A total of 118 patients diagnosed using EBUS-GS-TBB in Nippon Medical School Hospital between July 2016 and April 2018 were evaluated. In 101 patients with a definitive diagnosis, diagnostic factors of peripheral pulmonary lesions using EBUS-GS-TBB were retrospectively analyzed. According to the probe location, echo findings were divided into four groups: 'within', 'outside', 'broadly adjacent to' and 'narrowly adjacent to'. When the angle of the lesion around the probe in the EBUS-GS-TBB images was from ≥180 to <360 degrees, the echo finding was defined as 'broadly adjacent to'. Other findings in the 'adjacent to' group were classified as 'narrowly adjacent to'. Results. The rate of definitive diagnosis using EBUS-GS-TBB was 78.2% (79/101 patients). A multivariate analysis revealed that the echo findings of 'within' or 'broadly adjacent to' were a significant predictive factor (odds ratio [OR]=4.25; P<0.01). The diagnostic rate in patients with pulmonary emphysema was significantly lower than the rate reported in other patients (OR=0.29; P=0.02). In patients who underwent thin-section computed tomography, 'bronchus sign' was a significant predictive factor versus patients who did not undergo thin-section computed tomography (83.7% vs 42.9%, respectively, OR=6.86; P=0.03). Conclusion. Echo findings of 'within' and 'broadly adjacent to' should be obtained to improve the diagnostic yield of EBUS-GS-TBB. The diagnostic yield of EBUS-GS-TBB was low in patients with pulmonary emphysema. Presence of pulmonary emphysema before EBUS-GS-TBB should be evaluated.