The goal of this clinical trial is to learn whether the number of needle agitations during endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) affects diagnostic yield in patients with enlarged mediastinal lymph nodes. The study will also evaluate tissue sample quality and the safety of different needle agitation strategies.

The main questions it aims to answer are:

Does the number of needle agitations improve diagnostic yield? Does a higher number of needle agitations increase tissue core length and specimen adequacy? Are there differences in procedure-related complications between the two needle agitation strategies? Researchers will compare two needle agitation strategies during EBUS-TBNA to see if one approach provides better diagnostic performance, improved sample quality, and similar procedural safety.

Participants will:

• Undergo EBUS-TBNA as part of their clinical evaluation
• Be randomly assigned to one of two needle agitation strategies
• Have tissue samples measured for core length and assessed for diagnostic adequacy
• Be monitored for procedure-related complications

Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) has become the standard minimally invasive modality for sampling mediastinal lymph nodes in patients with suspected thoracic malignancies and benign lymphadenopathies. Despite its widespread adoption and high overall diagnostic performance, variability in procedural techniques may contribute to heterogeneity in specimen quality and diagnostic yield.

Among procedural factors, the number of needle agitations performed during each needle pass represents a modifiable technical variable that may influence tissue acquisition. Increased needle agitation may theoretically enhance tissue yield and core length by promoting mechanical dissection of nodal tissue; however, excessive agitation may also increase blood contamination, reduce sample interpretability, or elevate procedural trauma risk. Conversely, fewer agitations may limit tissue disruption but potentially result in inadequate sampling. Currently, there is no high-level evidence establishing an optimal agitation strategy, and operator-dependent variability remains common in clinical practice.

This randomized, single-blind controlled trial is designed to compare two predefined needle agitation strategies during EBUS-TBNA. By standardizing all other procedural variables, the study aims to isolate the effect of agitation number on diagnostic performance. Objective procedural metrics, including measured tissue core length and specimen adequacy, will be systematically assessed to provide quantitative evaluation of sample quality. Procedural safety outcomes will also be monitored to evaluate whether differences in agitation strategy influence complication rates.

The results of this trial are expected to provide evidence-based data to support technical standardization of EBUS-TBNA and to inform procedural guidelines aimed at optimizing diagnostic efficiency while maintaining safety.

Inclusion Criteria:

• Age ≥ 18 years
• Presence of enlarged mediastinal or hilar lymph nodes requiring diagnostic evaluation on chest computed tomography (CT), defined as short-axis diameter ≥ 10 mm measured on axial images
• Clinical indication for EBUS-TBNA
• Ability to provide written informed consent

Exclusion Criteria:

• Uncorrected coagulation disorders (platelet count < 100,000/mm³; International normalized ratio (INR) > 1.5; or prothrombin time < 50% of control)
• Acute myocardial infarction within the preceding 4 weeks or ongoing unstable angina
• Significant upper airway obstruction (benign or malignant) with ≥ 50% reduction in tracheal lumen diameter
• Hemodynamic instability (e.g., persistent hypotension, significant arrhythmia, or need for vasopressors)
• Respiratory failure refractory to oxygen therapy, defined as sustained Peripheral oxygen saturation (SpO₂) ≤ 90% despite supplemental oxygen
• Intractable cough precluding bronchoscopy
• History of severe allergy to local anesthetics or sedative agents used during the procedure
• Refusal or inability to provide informed consent

De-identified individual participant data underlying the results reported in the publication, including demographic characteristics, procedural variables, primary and secondary outcome data, and safety outcomes.

Data will be available beginning 6 months after publication of the primary results and will remain available for 5 years following publication.

Access will be granted upon reasonable request to researchers who provide a methodologically sound proposal. Requests will be reviewed by the principal investigator and, where required, the institutional review board. De-identified data will be shared after execution of a data use agreement.

The pathologists evaluating the tissue specimens will be blinded to group allocation. Participants will not be informed of the assigned needle agitation strategy.