The upper gastrointestinal tract can be compressed to varying degrees by peripheral organs and occupying lesions, and imaging can reveal signs of a bulging gastrointestinal tract wall. Gastroscopy and barium meal are difficult to differentiate between them. Small probe endoscopic ultrasonography (mEUS) has the advantages of flexible and convenient operation and clear display of the hierarchical structure of the digestive tract wall, and has obvious advantages in the diagnosis of external pressure augmentation. We reviewed and analyzed 115 cases of external pressure bulges in the upper gastrointestinal tract that were examined by mEUS. 1. Subjects and methods 1.1 Subjects 115 patients, 54 males and 61 females, with an average age of 51 years (18-82 years), who underwent small probe endoscopic ultrasound examination of upper gastrointestinal tract external pressure augmentation between May 2002 and August 2007. 1.2 Instruments and methods A PENTEX EG-3840T double-clamp channel electronic gastroscope, a PENTEX CGI-4000 electrocoagulation-water injection machine, and a FUJINON-SP-701 small probe ultrasound system with probe frequencies of 7.5 MHz, 12 MHz, and 20 MHz were applied. a routine upper gastrointestinal tract examination was first performed with the double-clamp channel gastroscope, and the site of the augmentation was clarified with a clamp channel The upper gastrointestinal tract was first examined with a double-clamp gastroscope, and then one clamp channel was used to submerge the lesion in water, and the other clamp channel was used to feed the small ultrasound probe for ultrasonography. 2. Results Among 115 cases of extrinsic pressure augmentation of the upper gastrointestinal tract, 35 cases (30.4%) were esophagus, 1 case (0.9%) was cardia, 74 cases (64.3%) were stomach, and 5 cases (4.4%) were duodenum. Physiological changes were seen in 98 cases (85.2%), of which spleen compression of the gastric fundus was the most common, with 45 cases (39.1%), the others were aortic compression of the esophagus in 19 cases (16.5%), liver in 14 cases (12.1%), normal gallbladder in 5 cases (4.4%), trachea in 4 cases (3.5%), spine in 4 cases (3.5%), pancreas in 3 cases (2.6%), heart in 2 cases (1.7%) There were 1 case (0.9%) of vascular compression of the gastric fundus and 1 case (0.9%) of intestinal canal. There were 17 cases (14.8%) with pathological changes, 7 cases (6.1%) with enlarged gallbladder; 8 cases (7.0%) with extramural lesions compressing but not invading the wall of the digestive duct, among which 2 cases of mediastinal tuberculosis were reexamined after 1 year of anti-tuberculosis treatment to see the disappearance of esophageal bulge and mediastinal mass, 2 cases of mediastinal tumor, 3 cases of abdominal tumor and 1 case of pancreatic pseudocyst combined with CT or MRI to make the diagnosis; extramural lesions compressing and invading the wall of the digestive duct There were 2 cases (1.7%) of extramural lesions compressing and invading the wall of digestive duct. 1 case of mEUS diagnosed as intrinsic myxoid mesenchymal tumor in esophagus and gastric fundus, respectively, and surgery confirmed as lung cancer and abdominal metastatic squamous carcinoma invading the wall of digestive duct. The sites and types of external pressure augmentation are shown in Table 1. 3. Discussion Endoscopy combined with tissue biopsy can lead to a clear diagnosis of many GI mucosal lesions, but endoscopy is often unable to make a diagnosis for lesions deep in the mucosa and below, and for augmented lesions in the upper GI tract compressed by extra GI organs or lesions. mEUS allows ultrasound scanning of the suspected lesions and their surroundings under direct endoscopic view, thus obtaining clear ultrasound images, and for extramural compression lesions of organs or lesions outside the GI tract, mEUS can clearly show the level of the canal wall at the site of compression, and the characteristic images of the compressed organ or lesion can be seen, which can accurately identify canal wall lesions and extramural compression of the GI tract, and is currently the best method for diagnosing extramural compression of the GI tract [1-4]. Most of the 115 cases of extramural compression bulges in the upper GI tract in our group were perimural organ compressions, and extramural compression bulges in the esophagus were mainly in the aortic arch, extrasplenic compressions in the gastric fundus were mostly in the spleen, and extrinsic gallbladder compressions in the gastric sinus and duodenal bulb, similar to those reported in the literature [5, 6]. Routine gastroscopy made an accurate diagnosis in all 98 cases of upper gastrointestinal peri-mural organ compression in our group, and the organ of compression was correctly determined in 96 of them; therefore, we believe that for upper gastrointestinal peri-mural organ compression, gastroscopy usually makes a correct diagnosis according to its augmentation site and morphological characteristics. For lesions that do not invade the wall of the gastrointestinal tract, mEUS can show the level of the wall at the site of compression and make the diagnosis of external pressure augmentation more easily. For lesions that invade the wall of the digestive tract, attention should be paid to differentiate them from lesions that grow outwardly in the wall of the digestive tract. Therefore, for large lesions that cannot be visualized in their entirety by mEUS, the diagnosis should be determined by using less frequent EUS or in combination with other imaging examinations. In addition, fine needle aspiration (EUS-FNA) and Turcut biopsy (EUS-TCB) for cytologic and histologic examination are also available for mediastinal and intra-abdominal occupying lesions to clarify the diagnosis.