Gastroesophageal reflux disease (GERD) is a chronic condition characterized by the persistent backflow of stomach contents into the esophagus. This reflux causes bothersome symptoms and can damage the esophageal lining over time. When symptoms are persistent or severe, or when complications are suspected, a physician may recommend an upper gastrointestinal endoscopy (EGD). The EGD uses a thin, flexible tube with a camera passed through the mouth to visually examine the lining of the esophagus, stomach, and duodenum. It serves as the primary tool for directly observing and classifying any visible injury caused by chronic reflux.
The Endoscopic View of a Healthy Esophagus
The normal esophageal lining, or mucosa, appears pale, smooth, and glistening white when viewed through the endoscope. This tissue is composed of stratified squamous epithelium, which is designed to be protective against abrasion.
The transition point between the esophagus and the stomach is a key landmark known as the gastroesophageal junction (GEJ). Here, the pale, protective esophageal lining abruptly meets the deeper pink or salmon-colored lining of the stomach. This demarcation line is called the Z-line, or the squamocolumnar junction.
In a healthy individual, the Z-line presents as a slightly irregular or zig-zag pattern. This precise location is where a gastroenterologist begins to look for the earliest signs of reflux injury. The absence of visible inflammation or breaks in the mucosa proximal to this line confirms a normal endoscopic result.
Recognizing Inflammation and Erosive Damage
The earliest and most subtle signs of GERD-related injury are associated with Non-Erosive Reflux Disease (NERD). These non-erosive findings include a general redness (erythema) of the mucosa near the Z-line, and a slight swelling (edema). Another subtle sign is mucosal thickening, which can sometimes make the underlying blood vessels invisible to the endoscope.
Non-erosive changes, such as the blurring of the Z-line’s sharp demarcation, suggest inflammation but are not always definitive proof of reflux disease. However, the presence of definitive erosive esophagitis provides clear visual evidence of acid damage. Erosions appear as distinct mucosal breaks, which are defects in the esophageal lining.
These breaks can be patchy or run in linear streaks, often appearing to follow the folds of the esophageal tissue. In more severe cases, these defects may be covered by a white or yellow film, which is a fibrinous exudate, essentially a layer of inflammatory debris. The diagnosis of erosive esophagitis is established when these visible, patchy, or striated epithelial defects are confirmed in the distal esophagus.
Grading the Severity of Reflux Esophagitis
When definitive mucosal breaks are identified, gastroenterologists use the standardized Los Angeles Classification (LA Classification) to grade the severity of the damage. This classification divides the erosive findings into four distinct grades (A through D) based on the size and confluence of the mucosal breaks. The LA Classification provides a framework for determining the appropriate course of treatment.
Grade A, considered the mildest form, is defined by the presence of one or more mucosal breaks that are no longer than five millimeters in length. Crucially, these small breaks do not extend continuously between the tops of two mucosal folds. This grade represents the initial stage of visually identifiable tissue damage.
Grade B involves mucosal breaks that are longer than five millimeters, making them visually more significant than Grade A lesions. These longer breaks must still be limited to one fold and cannot extend across the tops of two separate folds. Both Grade A and B are considered mild to moderate reflux esophagitis.
A substantial increase in severity is seen in Grade C, where the mucosal breaks extend across the tops of two or more mucosal folds. This indicates that the damage is starting to become confluent around the circumference of the esophagus. However, the breaks in Grade C must still involve less than 75% of the total esophageal circumference.
Grade D represents the most severe form of erosive reflux esophagitis, characterized by mucosal breaks that are confluent and involve 75% or more of the esophageal circumference. This extensive damage suggests prolonged and severe exposure to gastric refluxate.
Advanced Findings and Long-Term Complications
Beyond the acute inflammation and erosions, an endoscopy can reveal findings that represent long-term consequences of chronic GERD. One such complication is the esophageal stricture, which appears as a narrowing of the esophageal lumen. Strictures occur when the chronic inflammation and subsequent healing process lead to scar tissue formation, which constricts the passageway and can cause difficulty swallowing.
Another serious finding is Barrett’s Esophagus, a condition where the normal pale squamous lining of the esophagus is replaced by abnormal, salmon-pink or reddish-velvety columnar epithelium. This change, known as intestinal metaplasia, extends upward from the gastroesophageal junction. The distinctive color and texture difference makes Barrett’s tissue visually striking during the endoscopic examination.
Barrett’s Esophagus is a premalignant condition, meaning it is associated with an increased risk of developing esophageal adenocarcinoma. The endoscopic identification of this change, even in the absence of current erosions, is a significant finding that necessitates targeted biopsies for microscopic confirmation and regular endoscopic surveillance.