Associated factors with non-diagnostic histopathological examination in samples obtained by the endobronchial ultrasound-transbronchial needle aspiration: A retrospective cohort study

<bold>Background:</bold> Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is widely used for diagnosing pulmonary diseases causing mediastinal lymphadenopathy. However, non-diagnostic results may occur. This study investigates factors associated with non-diagnostic histopathological results in EBUS-TBNA. <bold>Methods:</bold> This retrospective cohort study included patients undergoing EBUS-TBNA at Ankara Bilkent City Hospital between March 14, 2019, and December 31, 2023. Patient demographics, biopsy techniques (forceps biopsy, bronchial lavage, transthoracic needle aspiration), histopathological results, sonographic lymph node measurements, and pre-procedural 18-FDG PET-CT SUVmax data were analyzed. <bold>Results:</bold> Of 863 patients, 776 (89.9%) were included. Among 502 males (64.7%), the mean age was 61.5 ± 12.6 years. Histopathology showed 109 (14%) patients in the non-diagnostic group, while 50.6% had non-malignant findings, 35.3% malignancy, and 17% granulomas. Samples were most frequently taken from the 7th station (72.9%), with an average of 5.9 ± 1.4 aspirations. Diagnostic patients had significantly more aspirations (p = 0.022) and larger lymph node sizes (p < 0.001). Each 1 mm increase in lymph node size raised diagnostic yield by 1.04 times (adjOR = 1.04, 95% CI = 1.02–1.08; p = 0.002). The largest lymph node size significantly predicted diagnostic results (AUROC = 0.611, 95% CI = 0.554–0.668, p < 0.001). A cut-off of 19.55 mm had 67.0% sensitivity and 52.2% specificity. <bold>Conclusions:</bold> Larger lymph nodes improve EBUS-TBNA diagnostic yield, reducing repeat procedures and enabling early treatment.