EBUS-TBNA needle rinse fluid: a superior specimen for the molecular diagnosis of intrathoracic lymph node tuberculosis

Objectives: To evaluate EBUS-TBNA needle rinse fluid versus biopsy tissue for molecular diagnosis of intrathoracic lymph node tuberculosis (TB). Methods: Retrospective analysis of 63 patients with intrathoracic lymph node TB undergoing EBUS-TBNA (2018-2024). Rinse fluid and biopsy tissue were tested via TB-DNA (n=32) and Xpert MTB/RIF (n=31); positivity rates compared. Results: The study cohort had a median age of 31 years (interquartile range: 25-50.1 years), with 57.1% (36/63) being male. The most frequently sampled lymph node stations were subcarinal (station 7, 82.5%) and right lower mediastinal (station 4R, 66.7%). Clinically, 82.5% (52/63) of patients had concomitant pulmonary TB, while 17.5% (11/63) presented with isolated intrathoracic lymph node TB. For TB-DNA detection, the positivity rate of rinse fluid (71.9%, 23/32) was significantly higher than that of biopsy tissue (46.9%, 15/32; χ²=4.146, P = 0.042). Similarly, the Xpert MTB/RIF assay showed a higher positivity rate in rinse fluid (77.4%, 24/31) compared to tissue (41.9%, 13/31; χ²=8.11, P = 0.004). Conclusions: EBUS-TBNA rinse fluid demonstrates higher sensitivity than biopsy tissue for intrathoracic lymph node TB via TB-DNA/Xpert MTB/RIF. Routine rinse fluid testing improves diagnostic yield.