A Comprehensive Cross-sectional Analysis on the Diagnostic Predictors of Endobronchial Ultrasound-guided Transbronchial Needle Aspiration

Introduction: Endobronchial Ultrasound-guided Transbronchial Needle Aspiration (EBUS-TBNA) is a relatively new and minimally invasive procedure for sampling mediastinal and hilar lymph nodes. Various factors can influence the diagnostic yield of EBUS-TBNA and comprehensive studies evaluating them together are scarce.

Aim: To evaluate the factors predicting the diagnostic yield of EBUS-TBNA in sampling mediastinal and hilar lymph nodes.

Materials and Methods: A cross-sectional study was conducted for the period of one year from June 2019 to May 2020. The patients with enlarged mediastinal and hilar lymph nodes on Computed Tomography (CT) thorax underwent Fibre Optic Bronchoscopy (FOB) followed by EBUS-TBNA under conscious sedation. Patient and procedure related factors and ultrasonological features of lymph nodes were noted. Their relationships with EBUS-TBNA histopathological results were assessed. Statistical methods like Fisher’s exact test with significant p-value as <0.05 were used for analysis.

Results: The mean age was 60.78±13.664 years with 59 (81%) males. Out of 73 lymph node stations sampled, 49.3% were subcarinal, followed by right lower paratracheal (30.1%), left hilar (8.2%), left upper paratracheal (6.9%) and left lower paratracheal (5.5%). EBUS-TBNA Histopathology Report (HPR) came as positive in 68.5% (50/73) cases with squamous cell carcinoma found in 34%, adenocarcinoma in 32%, poorly differentiated carcinoma in 16%, tuberculosis in 14%, and non specific inflammation in 4% cases. Significant association was found with factors like moderate sedation, duration of procedure taking >30 minutes, lymph node size >1 cm and absence of hilar sign, more number of passes per node and use of suction while sampling lymph nodes and diagnostic yield by EBUS-TBNA (p-value <0.05). There was no significant association with lymph node stations, lymph node features like shape, margin, echogenicity, necrosis and Rapid On-Site Evaluation (ROSE) and diagnostic yield; so also is the case with patient related factors like age, sex, co-morbidities, FOB and CT findings.

Conclusion: The duration of the procedure, type of sedation, lymph node size and absence of hilar sign, number of passes per node and use of suction while sampling the node are the main factors predicting the diagnostic yield of EBUS-TBNA in sampling mediastinal and hilar lymph nodes.