Although mediastinoscopy is still the gold standard for diagnosis of mediastinal lymphadenopathy, minimally invasive procedures have been developed: transbronchial needle aspiration (TBNA) using a flexible bronchoscope (conventional TBNA) or linear echoendoscope (endobronchial ultrasound [EBUS]) allowing real-time guided lymph node aspiration. The observation of contamination of samples by foreign particles led us to determine the frequency and the nature of this material and to identify its origin.
From June 2007 to November 2008, 141 consecutive patients underwent conventional TBNA (n = 84) or EBUS-guided TBNA (EBUS-TBNA) (n = 57). All cytologic samples were reviewed in blinded fashion, and contamination was assessed semiquantitatively. Mineral analysis using a transmission electron microscope equipped with an energy dispersive x-ray spectrometer was performed on the solution obtained after rinsing unused needles and on four samples of calf thymuses punctured with EBUS needles.
Foreign material, different from anthracosis, was identified in samples obtained with five different batches of needles, only from EBUS-TBNA (P < .0001). The contamination score was correlated to the number of passes (P = .035). Mineral analyses of the rinsing solutions from conventional TBNA needles were negative, whereas metal alloys of iron, titanium, nickel, and chromium were released with EBUS needles. The same contamination was identified in three of the four punctured calf thymuses.
Dedicated EBUS-TBNA needles are able to release metal particles, probably by friction between the stylet and the needle, with a potential risk to inject particles into nodes. The long-term consequences are unknown, but the need for safety measures should be evaluated.