Gastroesophageal reflux disease (GERD) - Types

Currently, many different classifications of gastroesophageal reflux disease have been proposed, but the Savary-Miller classification is of greatest interest for practice.

Endoscopic classification of GERD according to Savary and Miller (1978)

0 degree	GERD without esophagitis (endoscopically negative).
1st degree	Isolated non-confluent erosions and/or erythema of the distal esophagus.
II degree	Erosive lesions that merge but do not cover the entire surface of the mucosa.
III degree	Ulcerative lesions of the lower third of the esophagus, merging and covering the entire surface of the mucosa.
IV degree	Chronic esophageal ulcer, stenosis, Barrett's esophagus (cylindrical metaplasia of the esophageal mucosa).

That is, esophagoscopy is one of the main methods for assessing the severity of reflux esophagitis, but does not provide the ability to diagnose GERD in the early stages, in the absence of changes in the esophageal mucosa, or to assess the frequency and duration of pathological reflux.

In 1997, at the 6th European Gastroenterology Week, a new classification of gastroesophageal reflux disease was presented, which is based not on the degree of severity, but on the extent of the lesion (hyperemia, erosion, etc.). Moreover, complications of GERD (ulcer, stricture, Barrett's esophagus), according to the Savary-Miller classification, which belonged to the 4th degree, according to the Los Angeles classification, can be present with a normal state of the mucosa or at any other stage of GERD.

• Grade A - damage to the mucous membrane within the folds of the mucous membrane, with the size of each affected area not exceeding 5 mm.
• Grade B - the size of at least one lesion exceeds 5 mm; the lesion is within one fold, but does not connect two folds.
• Grade C - areas of mucosal involvement are connected between the apices of two or more folds, but less than 75% of the esophageal circumference is involved.
• Grade D - lesions cover at least 75% of the esophagus circumference.

In the endoscopically negative form of GERD, the main instrumental method that allows confirming the diagnosis is daily monitoring of intraesophageal pH. This method allows not only to identify and evaluate the nature, duration and frequency of reflux, but also to select and evaluate the effectiveness of therapy.

When interpreting pH readings in the esophagus, the following parameters are assessed:

• the total time during which the pH takes values less than 4 units. This indicator is also assessed in vertical and horizontal body positions;
• total number of refluxes per day;
• number of refluxes lasting more than 5 minutes each;
• duration of the longest reflux episode;
• esophageal clearance. This indicator is calculated as the ratio of the total time with a pH greater than 4 in the supine position to the total number of refluxes during this time, i.e. equal to the average duration of reflux in the supine position. Esophageal clearance is calculated only for the period in the supine position to exclude the influence of gravity;
• reflux index. Calculated as the number of refluxes per hour during the studied period of time in the supine position, excluding the period of time with a pH of less than 4.

In pH-metric studies, gastroesophageal reflux is usually understood to mean episodes in which the pH in the esophagus drops below 4.0 units. Normal values in the terminal section of the esophagus are 6.0-8.0 units. Gastroesophageal reflux also occurs in healthy people, but the duration of reflux should not exceed 5 minutes, and the total decrease in pH to 4.0 units and below should not exceed 4.5% of the total recording time. That is, the presence of pathological reflux is indicated by:

• acidification of the esophagus lasting more than 5 minutes;
• a decrease in pH to less than 4 for a period exceeding 4.5% of the total recording time.

Reflux lasting 6-10 minutes is considered moderately pronounced, while reflux lasting more than 10 minutes is considered severely pronounced.

Normal pH-gram in the esophagus with 24-hour monitoring. On the pH-gram, the average pH level in the esophagus fluctuates from 6.0 to 8.0, short-term physiological acid refluxes were recorded, mainly during the daytime.

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