Endobronchial Ultrasound (EBUS) Biopsy of Mediastinal Lymph Nodes
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Introduction
Mediastinoscopy is the ‘gold standard’ method for determining the presence of nodal metastases in the mediastinum. Generally performed as an outpatient surgical procedure, it is associated with a low rate of serious adverse effects (<1%) and the procedure is highly accurate, with false negative rates reported to be between 6% and 9%. Endobronchial ultrasound (EBUS) guided fine needle aspiration biopsy of mediastinal nodes offers a less invasive alternative for histologic sampling of the mediastinal nodes. The procedure has been widely adopted by pulmonologists and is poised to replace mediastinoscopy in the future. For thoracic surgeons, the technique can be easily learned and it may be important to do so if our specialty is to maintain its traditional and important role in the diagnosis and staging of thoracic malignancies.
The EBUS bronchoscope (BF-UC160F-OL8; Olympus America Inc., Center Valley, PA) is similar in dimensions to a standard adult fiber optic bronchoscope. The 6 mm diameter scope has a curvilinear ultrasound (US) probe at its distal end which provides a 50 degrees linear continuous B-mode ultrasound image, with color Doppler capability to aid identification of vascular structures (Figure 1). Proximal to the US probe, and at 30 degrees to the long axis of the bronchoscope, are a fiber optic lens and a biopsy channel, through which a 22-G biopsy needle can be passed (NA-201SX-4022; Olympus America Inc., Center Valley, PA) (Figure 2). A disposable latex balloon is placed over the US probe, which is inflated with sterile water to provide a fluid interface between the probe and the tracheal wall.
Figure 1: Olympus BF-UC160F-0L8 endobronchial ulrasound bronchoscope. Saline filled syringe attached to balloon inflation port.
Figure 2: Inflated balloon with needle and sheath advanced.
Figure 3: EBUS being performed under general intravenous anesthesia with use of laryngeal mask airway. The CV-180 video processor enables picture-in-picture display, which allows easy correlatoin between visualized anatomy and the ultrasonic image.
Figure 4: Fiberoptic image of distal trachea with balloon partially inflated.
Figure 5: EBUS processor (EU-C60; Olympus America Inc., Melville, NY).
Figure 6a: Ultrasound image of R main pulmonary artery with (right) and without (left) color Doppler.
Figure 6b: Biopsy of right paratracheal node (arrow) with superior vena cava visualized in its long axis anteriorly.
Figure 7: Measuring short axis dimension of a subcarinal lymph node.
Figure 8a: Biopsy neelde (NA-201SX-4022; Olympus America Inc., Center Valley, PA) secured to biopsy port of EBUS scope. The sheath screw is first released to allow the sheath to approximate the tracheobronchial wall. When the sheath is in contact with the bronchial wall a slight distorting effect can be seen at the upper right corner of the US image.
Figure 8b: With the sheath appropriately advanced and secured by retightening the screw, the biopsy screw is then released. This will allow the biopsy guard to slide out of the way in preparation for needle advancement.
Figure 8c: Once the needle screw has been released, the biopsy needle can usually be easily advanced through the tracheobronchial wall and into the node using a quick, slightly forceful jab.
Figure 9: Right paratracheal node (4R) between truncus anterior of R PA (red arrow) and azygos vein (blue arrow). Biopsy needle is advanced through the node (white arrow).
Figure 10: Visual placement of needle into intercatillaginous mucosa (left) with slight advancement of scope to increase angle of attack as needle is advanced (right) into a paratracheal node.
Figure 11: EBUS aspirated cells from a squamous cell carcinoma metastatic to a paratracheal lymph node. Smaller cells are lymphocytes.
