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

## TL;DR

This study shows that rinse fluid collected during EBUS-TBNA is more effective than biopsy tissue for diagnosing tuberculosis in intrathoracic lymph nodes.

## Contribution

The study demonstrates that EBUS-TBNA rinse fluid has higher diagnostic sensitivity than biopsy tissue for TB detection using molecular tests.

## Key findings

- Rinse fluid had a 71.9% positivity rate for TB-DNA compared to 46.9% in biopsy tissue.
- Xpert MTB/RIF showed 77.4% positivity in rinse fluid versus 41.9% in tissue samples.
- Most patients had concomitant pulmonary TB, with subcarinal and right lower mediastinal lymph nodes most commonly sampled.

## Abstract

To evaluate EBUS-TBNA needle rinse fluid versus biopsy tissue for molecular diagnosis of intrathoracic lymph node tuberculosis (TB).

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.

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).

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.