Adjacent angle size correlates with diagnostic sensitivity of endobronchial ultrasonography with a guide sheath

An association exists among the diagnostic yield of transbronchial biopsy using endobronchial ultrasonography with a guide sheath (EBUS-GS-TBB) and several factors, such as simple within or adjacent endobronchial ultrasonography (EBUS) findings. Here, we aimed to investigate whether more detailed EBUS findings affect the diagnostic yield of lung cancer in EBUS-GS-TBB.

We conducted this retrospective single-center cohort study, enrolling consecutive patients with lung cancer who underwent EBUS-GS-TBB. The primary outcome was examination of predictive factors affecting the diagnostic yield of lung cancer using EBUS-GS-TBB. The secondary outcome was a subgroup analysis of within and adjacent lesions. The adjacent angle was defined as the angle formed by the midpoint of the probe and the two points where the edge of the probe and shadow of the tumor intersected.

Of the 179 lesions investigated, 140 (78.2%) were diagnosed using EBUS-GS-TBB. The diagnostic yields of within and adjacent lesions were 91.6% and 51.7%, respectively. In the multivariable analysis, within lesions had significantly higher diagnostic yields than did the adjacent lesions (P<0.001). The adjacent angle was larger in lesions diagnosed using EBUS-GS-TBB than in undiagnosed lesions (P=0.003). In adjacent lesions, the diagnostic yields were 75.0% and 36.1% for lesions ≥180° and <180°, respectively.

In adjacent lesions, the diagnostic yields differed significantly depending on the adjacent angle. Even if EBUS findings are adjacent, the operator should identify the branch of the bronchus with a greater adjacent angle. Future studies should investigate improvements in diagnostic yields via additional procedures for lesions with small adjacent angles.