Prospective randomized trial to compare the safety, diagnostic yield and utility of 22-gauge and 19-gauge endobronchial ultrasound transbronchial needle aspirates and processing technique by cytology and histopathology.

Introduction: Endobronchial ultrasound (EBUS)-guided transbronchial needle aspirate (TBNA) is a widely used method of minimally invasive lymph node sampling. The benefit of processing samples by cytologic methods versus "core biopsy" is unclear. It is unknown if safety or diagnostic yield varies by needle gauge.

Materials And Methods: Between June 2018 and July 2019, 40 patients (56 lesions) undergoing EBUS TBNA lymph node evaluation were enrolled in this single-center prospective trial. Patients were chosen by permuted block randomization to undergo EBUS TBNA starting with 22-gauge (22g) or 19-gauge (19g) needles. Separate samples were sent for processing by cytologic methods and histopathology. Surgical pathologists and cytopathologists were blinded to needle size. The primary endpoint was diagnostic yield. Secondary endpoints compared specimen adequacy by rapid onsite evaluation (ROSE), sample adequacy for molecular testing, sample quality, and safety.

Results: Diagnostic yield for histopathologic examination was 87.5% and 83.9% for 19g and 22g respectively (P = 0.625). There was no significant difference in diagnostic yield by cytologic examination based on needle size. There was no significant difference in slide quality. Molecular adequacy for core-biopsy was 77% and 80% for 22g and 19g needles, respectively. Molecular adequacy for cytology cell block was 77% and 80% for 22g and 19g needles, respectively. There were no significant procedural complications.

Conclusion: Both the 22g and 19g EBUS TBNA needles provided a similar diagnostic yield and clinical utility for ancillary testing. Processing techniques by cytologic methods or "core biopsy" showed no significant impact in diagnostic yield or utility of molecular testing.