Introduction Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is a minimally invasive mediastinal node sampling technique used for lung cancer staging and diagnosis of malignant and benign lesions. Sampling is done with either 21-gauge (21G) or 22-gauge (22G) needles. There are only two published (non-UK) studies which have evaluated the effect of EBUS-TBNA needle gauge on diagnosis.^1,2 Neither study demonstrated a difference in diagnostic yield but one study suggested better preservation of histological structure with the 21G needle.¹ The aim of this retrospective UK study was to evaluate the diagnostic utility of 21G versus 22G EBUS-TBNA needles. Our hypothesis was that the 21G needle would allow greater histological characterisation of non-small cell lung cancer (NSCLC) and benign mediastinal lesions.

Methods A retrospective analysis was performed from 185 patients referred for EBUS-TBNA between 2011 to 2012. EBUS-TBNA was performed as previously described under conscious sedation.3 21G or 22G (Olympus ViziShot, NA-201SX-4021 and NA-201SX-4022) was used at the discretion of the operator. Pathologists were blinded to needle gauge. Contingency table statistical analysis was performed (GraphPad Prism version 5) to compare diagnostic utility of 21G and 22G EBUS-TBNA needles and ability to subcharacterise NSCLC and benign lesions.

Results Performance data (table 1) showed non-inferior diagnostic utility for 21G and 22G needles. Subgroup analysis of benign 21G tissue samples revealed superior characterisation (especially for sarcoidosis) compared to 22G samples (30/37, 81%, versus 17/33, 52%, p=0.008). Similarly, characterisation of NSCLC was superior in 21G samples versus 22G samples (28/33, 85%, versus 25/41, 61%, p=0.02).

Conclusion This UK single centre retrospective study suggests 21G EBUS-TBNA needles are superior in characterising benign lesions (especially sarcoidosis) and NSCLC Making a positive benign diagnosis avoids the need to perform mediastinoscopy; additionally, identification of lung adenocarcinoma allows appropriate epidermal growth factor receptor mutation testing and targeted oncological therapy.

References

1. Nakajima T, Yasufuku K, Takahashi, Shingyoji M, Hirata T, Itami M, Matsui Y, Itakura M, Ilzasa T, Kimura H. Comparison of 21-gauge and 22-gauge aspiration needle during endobronchial ultrasound-guided transbronchial needle aspiration. Respirology (2011); 16: 90–94.

2. Oki M, Saka H, Kitagawa C, Kogure Y, Murata N, Ichihara, Mortamni S, Ando M. Randomized study of 21-gauge versus 22-gauge endobronchial ultrasound-guided transbronchial aspiration needles for sampling histology specimens. J Bronchol Intervent Pulmonol (2011); 18:306–310.

3. Medford AR, Agrawal S, Free CM, Bennett JA. A performance and theoretical cost analysis of endobronchial ultrasound-guided transbronchial needle aspiration in a UK tertiary respiratory centre. QJM (2009); 102(12):859–64.