Barrett’s esophagus (BE) is a replacement of the distal esophageal squamous mucosa with columnar-lined epithelium of both gastric and intestinal types (1). Today, Barrett’s esophagus is defined as the presence of columnar appearing mucosa anywhere within the esophagus and specifically refers to intestinal metaplasia that contains Alcian blue-positive goblet cells (2). A histologic diagnosis of intestinal metaplasia is necessary to make the diagnosis of BE. When there are ≤3 cm of columnar epithelium protruding into the squamous epithelium of the esophagus, it is defined as short segment BE (Fig. 7.1) (3). When there are >3 cm of columnar epithelium extending into the esophagus, it is defined as long segment BE (Fig. 7.2). Because most instances of esophageal adenocarcinoma have BE as a precursor, it is necessary to be able to recognize the endoscopic features of BE. This requires a thorough understanding of distal esophageal endoscopic anatomy. (See Chapters 3 and 6.)

There are four items the endoscopist must recognize and evaluate in order to identify the presence of BE. These are the terminal linear esophageal blood vessels, the lower esophageal sphincter (LES), the squamocolumnar junction (SCJ), and the gastroesophageal junction (GEJ). The LES is generally located 38 to 41 cm from the nasal vestibule. When only a small amount of air is insufflated into the esophagus, the normotensive LES can typically be identified as a closed rosette of esophageal mucosal folds. The LES rests at the distal, coned-down end of several longitudinal, symmetrical esophageal mucosal folds (Fig. 7.3). Because this region

is where the diaphragmatic crura “pinches” the esophagus as it passes through the diaphragm, this area is also known as the “diaphragmatic pinch.” The anatomic relationship of the LES and the diaphragm will be distorted in the presence of a hiatal hernia, and the gastric rugae will be above the diaphragmatic pinch.

The SCJ is normally at the level of the GEJ. The SCJ is the point where the gray-white squamous epithelium of the esophagus ends and the salmon- or pink-colored columnar epithelium of the stomach begins (Fig. 7.4). The SCJ usually appears as a slightly irregular demarcating line also known as the “Z-line.” Several linear, gastric folds terminate at the level of the normal location of the squamocolumnar junction. The upper margin of these longitudinal gastric folds also corresponds to the level of the GEJ and provides a very useful landmark for the muscular junction between stomach and esophagus (Fig. 7.5). When the Z-line (SCJ) is located above the GEJ, there is columnar-lined epithelium in the esophagus.