What is the recommended approach for nodal staging based on EBUS (Endobronchial Ultrasound) stations?

Recommended Approach for Nodal Staging Based on EBUS Stations

For complete mediastinal nodal staging using EBUS, a minimum of three different mediastinal nodal stations (4R, 4L, 7) should be sampled, along with any abnormal lymph nodes identified by size (>10mm) or FDG avidity on PET imaging. 1, 2

Accessible Lymph Node Stations via EBUS-TBNA

EBUS-TBNA can access and sample the following lymph node stations:

• Paratracheal nodes: stations 2L, 2R, 4L, 4R
• Subcarinal node: station 7
• Hilar nodes: station 10
• Intrapulmonary nodes: stations 11-12

The diagnostic yield of EBUS-TBNA is directly related to those mediastinal and hilar nodes located immediately adjacent to the trachea and larger airways 1.

Limitations of EBUS-TBNA

• Stations 5 and 6 (aortopulmonary window) are generally not accessible via EBUS-TBNA alone
• These stations are predominantly affected by left upper lobe tumors
• For these stations, surgical staging by video-assisted thoracic surgery (VATS) is the method of choice 1

Combined Approach with EUS-(B)-FNA

To achieve complete mediastinal evaluation, combining EBUS-TBNA with EUS-(B)-FNA is recommended as it provides access to virtually all mediastinal nodal stations 1, 3, 4.

EUS-(B)-FNA can reach:

• Mediastinal lymph nodes in stations 2L, 4L
• Station 7 (subcarinal node)
• Stations 8 and 9 (nodes in lower mediastinum)
• Structures below the diaphragm

Stations 2R and 4R (paratracheally to the right) are difficult to reach with EUS due to the trachea lying between the transducer and the lymph node, though large lymph nodes (>2 cm) may still be visualized and sampled 1.

Thoroughness of Sampling

The European Society of Gastrointestinal Endoscopy (ESGE), European Respiratory Society (ERS), and European Society for Thoracic Surgery (ESTS) guidelines recommend different levels of thoroughness 1:

1. Complete sampling - each node in each major mediastinal node station (2R, 4R, 2L, 4L, 7, and possibly 5 or 6)
2. Systematic sampling - each node station
3. Selective sampling - suspicious nodes only
4. Limited sampling - visual assessment only

Risk Stratification for Negative EBUS-TBNA Results

For lymph nodes deemed negative by EBUS-TBNA, a risk stratification model can help determine which patients need further staging procedures 5:

High-risk factors for false negative results include:

• High lymph node standardized uptake value (SUV)
• High SUV ratio between lymph node and primary tumor
• Heterogeneous echogenicity during sonographic assessment

Nodes classified as high risk (score ≥2 based on these factors) may warrant additional investigation despite negative EBUS-TBNA results 5.

Practical Recommendations

1. Begin with a thorough evaluation of all accessible lymph node stations
2. Sample at minimum the three key stations (4R, 4L, 7)
3. Target all abnormal lymph nodes identified by size or FDG avidity
4. For stations not accessible by EBUS (particularly stations 5 and 6), consider EUS or surgical approaches
5. When EBUS results are negative but clinical suspicion remains high, consider risk stratification to determine need for additional procedures

This approach ensures optimal mediastinal staging while minimizing the need for more invasive surgical procedures 1, 2, 3.