Only a few studies were published using EUS-B in non-malignant diseases.

In clinical practice, most patients with suspected sarcoidosis present stage I or II disease, characterized by increased lymph nodes. Current diagnosis of pulmonary sarcoidosis is shifting from conventional flexible bronchoscopy with accessory techniques to other minimally invasive techniques, with improved efficacy and safety. In recent years, the detection of non-caseating granulomas in mediastinal lymph nodes was easily performed by EBUS-TBNA or EUS-NA.33,34 In a 2013, Oki et al. used EUS-B-NA in 33 patients to diagnosis stage I/II sarcoidosis.35 They achieved a diagnostic yield of 86% without complications.

In other retrospective studies, EUS-B-NA allowed the diagnosis of tuberculosis lymphadenitis in both children and adults, during the differential diagnosis of mediastinal or hilar lymphadenopathies.24,36 In these situations, the diagnostic yield increases if samples are sent simultaneously for microbiology, cytopathology, and mycobacterium tuberculosis-polymerase chain reaction.37

There are no specific recommendations for EUS-B regarding minimal room and equipment requirements hence they are extrapolated from conventional bronchoscopy and EBUS guidelines.

In most cases, EUS-B can be safely done as an outpatient procedure in a bronchoscopy unit. The suite should be properly equipped for patient monitoring. A secure intravenous access is mandatory and specific anesthetic drugs should be at hand. Oxygen delivery systems and resuscitation equipment should also be readily available.38 The procedure is usually performed under moderate or deep sedation to achieve appropriate patient comfort and collaboration.39 In some cases, depending on local settings, the goal of the procedure (systematic staging vs. targeted diagnostic puncture) and the operator's experience, general anesthesia may be a valid option.

A certified bronchoscopist with formal endosonography training, two nurses – one to assist during the procedure and other dedicated to sedation – and an anesthesiologist, in case of deep sedation or general anesthesia, should be the minimal personnel requirements to perform the procedure securely.

The presence of a cytopathologist for rapid on-site evaluation (ROSE) does not seem to affect the diagnostic yield, but reduces the number of punctures, procedure time and can be useful to evaluate the quality of material and quantity of malignant cells, namely when molecular testing is planned.39

In terms of equipment, different electronic linear scanning echoendoscopes are commercially available (Table 1). When deciding which one to choose, several factors need to be considered, including the existence of compatible equipment already available (e.g. video processors, ultrasonography console), characteristics of the EBUS scope (direction of view, flexibility, distal end size, diameter of the working channel, video quality and ultrasonic image), as well as costs and post-vending manufacture assistance. The final decision depends on a compromise between these options.

Multiple disposable needles are available, all developed on the basis of the original construction of the Hancke-Vilmann needle system (GIP-Medizin Technik now Medi-Globe): a long-steel needle, a sheath and a handle for manipulation.40 Technological advancements have led to experimentation of new designs and materials that improve handling and performance but increase costs. Even though the main principles are the same, needles differ in several characteristics (Table 2). There are no prospective comparative studies showing the superiority of one needle39 over the others, so the operator needs to consider the handle design (ergonomic and maneuverability) and the characteristics of needle “per se” (durability, flexibility, echogenicity). Other features are, compatibility with the equipment and costs, especially if we aim for a needle that provides histological core samples (e.g. Vizishot Flex®, Echotip Procore®). According to recent guidelines, the operator should determine needle choice and either 21G or 22G are acceptable options for most cases.39

The EUS-B scope is inserted through the mouth into the esophagus gently rotating it with a screw movement, and advanced under visual control to the gastric fundus. While introducing the scope, suction should be used only in an intermittent manner, to avoid deflating the esophageal tract completely. The endoscopic view is not normally useful and endosonography scanning guides the procedure. From this moment on, continuous suction is mandatory to facilitate the contact between the ultrasound transducer and the esophageal wall. At the cardia region, the transducer is turned back until the abdominal aorta is clearly visualized in its longitudinal diameter (Fig. 4). To identify the LAG, the tip of the bronchoscope is slid down the aorta, up to the celiac trunk and mesenteric artery, which are the first vessels extending from the abdominal aorta. At this point, the EUS-B scope is turned counterclockwise (if the physician is standing behind a patient lying in supinal position this movement turns the transducer to the left) to visualize the left kidney, the spleen, and the LAG just behind the celiac trunk and mesenteric artery. After seeing the LAG, the transducer is brought back to its standard neutral position at the cardia. In front, the left lobe of the liver, diaphragm and heart are clearly visualized (Fig. 4A), and to the right the hepatic veins can be followed as they approach the inferior vena cava. Then scanning proceeds by withdrawing the transducer to the distal esophagus. The EUS-B scope is turned around from the descending aorta and back to the aorta again (Fig. 4B), visualizing retroperitoneal and para-aortic lymph nodes. If the scope is turned slightly more to the left, the diaphragm is clearly seen on the left corner and the right atrium on the right. At this level, the left pulmonary ligament lymph nodes (station 9) can be detected. During further withdrawal of the scope, from the distal to the middle part of the esophagus, para-esophageal (station 8) and lower para-aortic lymph nodes are seen posteriorly. Then the heart is visualized anteriorly, with the left ventricle coming first into focus, at that point the atrioventricular valves and the left atrium with pulmonary vein close to the esophageal wall. While withdrawing the scope slightly more, subcarinal lymph nodes (station 7), especially the posterior group, are clearly visible (Fig. 4C), and to the right, reflections from the trachea and the proximal wall of the right main bronchus are seen, as well as the right pulmonary artery in a transverse section. Further retreating the scope and looking anteriorly at the tracheal reflections at its lower part, slightly to the right, the posterior part of the right paratracheal lymph nodes (station 4R), behind azygos vein, can be found in many cases. At this level, rotating the EUS-B scope to the left will permit to detect the lower paratracheal (station 4L) and deeper aorto-pulmonary window lymph nodes (station 5) between the pulmonary artery and aorta (“mickey mouse effect”) (Fig. 4D). On the left, the entire descending intrathoracic aorta can be followed along the esophagus, and para-aortic lymph nodes (station 6) may be visualized through the aortic arch. Behind the aorta, reflections from the thoracic spine are well seen. As the EUS-B scope is further withdrawn, the left subclavian artery and upper left paratracheal lymph nodes (station 2L) are identified on the left side, and just behind them the left internal jugular vein is often found (Fig. 4E). To the level of the upper part of the esophagus, both lobes of the thyroid gland can be seen and below them seldom mediastinal highest lymph nodes (station 1) can be seen.

Figure 4.

CT view and EUS-B view of the main anatomic landmarks (Ao – aorta, D – diaphragm, H – heart, L – liver, LA – left atrium, Lu – lung, PA – pulmonary artery, SA – subclavian artery, V – vertebra).

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The technique for needle biopsy aspiration is similar to the one performed for EBUS-TBNA, but often easier because of the softness of the esophageal wall. On the other hand, the EUS-B-NA seems to be more difficult because of incorrect adjustment to the esophageal wall. Therefore, the reach of EUS-B is the same as for EUS: it is possible to puncture the LAG, left lobe of the liver, lymph node stations 2L, 4L, 7, 8, 9 (Fig. 5) and in specific situations the lower part of station 5, posterior part of station 4R and station 1.

Figure 5.

Sagital view of thorax CT with main acessible EUS-B lymph node stations (Ao – aorta, PA – pulmonary artery, LA – left atrium, L – liver).

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The intra-esophageal introduction of an EBUS-scope and its use for EUS-B-NA is safe. No serious complications have been reported. Nevertheless, the development of a lymph node abscess after simultaneous EBUS-TBNA was described in one subject.13 In a systematic review of combined EUS-NA and EBUS-TBNA for staging of mediastinal lymph nodes in lung cancer, severe complications were reported in two patients (0.3%), the patient with the lymph node abscess and a pneumothorax in an additional patient.41 However, the EBUS bronchoscope is not only thinner, but also sharper at the tip. This fact needs to be considered when the bronchoscope is used in the esophagus. If the esophagus is narrowed or a diverticulum is present, but not easily visible due to the side-view optic, there is a significant risk of iatrogenic bleeding due to mucosal damage or even of perforation of the esophageal wall (Fig. 6).

Figure 6.

Endoscopic image of the distal esophagus after EUS-B-NA shows a large iatrogenic perforation of the esophageal wall close to the cardia.

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