What is EBUS (Endobronchial Ultrasound)?

What is EBUS (Endobronchial Ultrasound)?

Endobronchial ultrasound (EBUS) is a minimally invasive bronchoscopic technology that allows real-time ultrasound visualization of structures adjacent to the airways, enabling guided needle sampling of mediastinal and hilar lymph nodes, parabronchial masses, and peripheral lung lesions. 1

Two Main EBUS Systems

EBUS technology exists in two distinct forms, each with specific diagnostic capabilities:

Linear (Convex Probe) EBUS

• Incorporates an ultrasound transducer into the tip of a standard bronchoscope, allowing real-time guided transbronchial needle aspiration (TBNA) of lymph nodes and masses adjacent to the airways 1
• Can access mediastinal lymph node stations 2L, 2R, 4L, 4R, and station 7 (subcarinal), as well as hilar nodes (station 10) and intrapulmonary nodes (stations 11-12) 1
• Achieves a median sensitivity of 89% and negative predictive value of 91% for mediastinal staging in lung cancer, making it superior to conventional staging methods 1, 2

Radial Probe EBUS

• Integrates a miniature ultrasound transducer into a freestanding probe that advances through the bronchoscope's working channel into the lung periphery 1
• Primarily used for sampling peripheral lung nodules and masses, and for evaluating central airway wall invasion 3, 4
• Provides 360-degree radial imaging but does not allow real-time needle guidance 5, 4

Primary Clinical Applications

Lung Cancer Diagnosis and Staging

• The American College of Chest Physicians recommends EBUS-TBNA as the first-line procedure over surgical staging for mediastinal evaluation in suspected lung cancer 1, 2
• Additional tissue samples beyond those needed for diagnosis should be obtained for molecular analysis in non-small cell lung cancer (Grade 1C recommendation) 1
• EBUS has transformed the diagnostic approach to mediastinal and hilar diseases over the past decade 1

Non-Malignant Conditions

• EBUS-TBNA is recommended for diagnosis of suspected sarcoidosis with mediastinal/hilar adenopathy (Grade 1C) 1, 2
• EBUS-TBNA is recommended for diagnosis of suspected tuberculosis requiring lymph node sampling (Grade 1C) 1, 2
• EBUS-TBNA is an acceptable initial minimally invasive test for suspected lymphoma 1, 2

Technical Performance Standards

Needle Selection and Sampling Technique

• Either 21-gauge or 22-gauge needles are acceptable options (Grade 1C recommendation) 1
• A minimum of 3 separate needle passes per sampling site should be performed when rapid on-site evaluation (ROSE) is not available 1
• Tissue sampling can be performed with or without suction (both approaches are acceptable) 1

Sedation Approach

• Either moderate or deep sedation is acceptable for EBUS-TBNA procedures (Grade 2C) 1

Rapid On-Site Evaluation (ROSE)

• Tissue sampling can be performed with or without ROSE (Grade 1C), though ROSE may improve diagnostic yield 1, 2

Complementary Use with EUS

• Combining EBUS with endoscopic ultrasound (EUS) allows sampling of virtually all mediastinal nodal stations 1
• EUS can reach stations 2L, 4L, 7,8, and 9, as well as left adrenal gland and retroperitoneal structures, while EBUS uniquely accesses hilar and intrapulmonary nodes 1
• Stations 2R and 4R are difficult to reach via EUS because the trachea blocks visualization, but are readily accessible via EBUS 1

Training Requirements

• Low or high-fidelity simulation should be incorporated in EBUS-TBNA training (Grade 2C) 1
• Validated EBUS skills assessment tests should be used to objectively evaluate operator competency 1, 2
• Trainees should participate in approximately 40 supervised procedures and become familiar with ultrasonic imaging 2

Safety Profile

• EBUS-TBNA is a safe procedure with rare complications, which are typically related to the needle aspiration itself rather than the ultrasound guidance 5, 4
• The procedure can be performed as an outpatient with short examination duration 4

Common Pitfalls

• Placement of an endotracheal tube may block ultrasonographic view of higher paratracheal lymph nodes (station 2R) and should be avoided if these nodes are sampling targets 6
• Ultrasonographic features can predict malignant versus benign diagnoses, but tissue samples must still be obtained to confirm diagnosis 1
• The procedure requires experienced operators to achieve optimal diagnostic yield 2, 5