Chromoscopy of the esophagus and stomach

Chromoendoscopy is a method of endoscopic examination of the gastrointestinal tract (GIT) with staining with various safe dyes for human presumed abnormal surface changes in the mucous membrane of the organs under investigation, which allows to detect and differentiate the minimal pathological changes in the epithelium of the mucosa by means of a comprehensive visual examination through the endofibroscope and histological examination of target biopsy materials . Sometimes the method of chromoendoscopy is defined as a method of staining the epithelial structures of the gastrointestinal tract, used in the examination of patients during an endoscopic examination.

To improve the effectiveness of cancer diagnosis, as well as differential diagnosis of benign and malignant lesions of the esophagus and stomach in endoscopic studies of these organs, doctors from different countries, along with a visual study of the mucosa and multiple targeted biopsies to obtain a more accurate material for histological and / or cytological studies , now more often use so-called "vital" dyes, resort to an additional method of examinations Nia patients - carrying chromoendoscopy.

Back in 1966, at the First World Congress of Gastroenterologists, a message was presented, the essence of which was to emphasize the advisability of using chromoscopy in the examination of patients by spraying the methylene blue dye on the surface of probable pathological changes in the mucous membrane during gastroscopy followed by a complex evaluation of these changes in the gastric mucosa . Later, chromoendoscopic examination of the esophagus and stomach began to be considered as a supplement to the usual endoscopic examination, and also increasingly conducted in the examination of other gastrointestinal organs. Currently, chromoendoscopy of the gastrointestinal tract is becoming increasingly common in the practice of examining patients.

Usually, when carrying out chromoendoscopy, depending on the available possibilities and contraindications to the use of various dyes in the examination of specific patients, solutions of Lugol, methylene blue, toluidine blue, Congo red or phenol red are used to diagnose gastrointestinal lesions, including the esophagus and / or stomach and others, among which there are sometimes isolated absorbing dyes and reagents.

Absorbent dyes (Lugol's solution, methylene blue, toluidine blue) are captured by special epithelial cells, which allows revealing pathologically altered sections of the gastrointestinal mucosa. The use of contrasting dyes (Congo red, phenol red) when examining patients with the gastrointestinal tract makes it possible in many cases to distinguish pathologically altered epithelium from unaltered sections of the gastrointestinal mucosa; most often these dyes are used in endoscopy, conducted with an increase. Reactive substances allow us to identify specific variants of the secret with which they react chemically, leading to a change in the color of the mucous membrane.

Conduction of endoscopic chromoscopy allows to determine squamous cell carcinoma of the esophagus, adenocarcinoma in the distal esophagus (the so-called "Barrett's cancer"), in the stomach - early cancer in risk groups (in patients with pernicious anemia, in patients with a squamous cell cancer of ENT organs in anamnesis , with achalasia of the cardia, with chemical burns of the esophagus, and also among persons with an "operated" stomach). Conducting chromoendoscopy is also shown in the diagnosis of early cancer before endoscopic mucosectomy for accurate detection of tumor boundaries. The most justified in such cases is the Lugol solution as the colorant. Lugol's aqueous solution (10 ml of a 1-4% solution of potassium iodine) reacts with glycogen of the normal flat multilayer epithelium of the esophagus mucosa and changes its color. Absorption of Lugol's solution by normal glycogen-containing cells helps to distinguish the boundaries of healthy tissue, dysplastic and neoplastic cells that do not contain glycogen, and therefore do not stain by this dye. Before carrying out chromoendoscopy, it is advisable to rinse the test organ with water for washing mucus, then apply the solution on the mucous membrane.

Unchanged, non-keratinizing epithelium after application of the dye after 2-3 seconds acquires a black, dark brown or greenish-brown color. The structure of the unmodified mucosa is "wrinkled". The sites of localization of leukoplakia become dark brown when stained. After 5-10 minutes, the colored sections of the mucosa (in the absence of additional effects on it) fade. It must be remembered that only healthy cells of the flat epithelium of the esophagus are colored and cells with marked inflammation (with esophagitis), dysplasia and / or cancer do not stain. Thanks to this, the coloring of Lugol's solution makes it possible to detect unchanged flat epithelium of the mucosa (positive staining) against the background of malignant epithelium (no staining). The absence of staining of the epithelium of the mucosa testifies to a decrease in glycogen in the cells of the non-corroborating epithelium with marked inflammation, dysplasia, metaplasia and early cancer. The glandular epithelium or metaplasia of the epithelium of Barrett's esophagus is also not stained with Lugol's solution. This method increases the sensitivity, specificity and accuracy of endoscopic detection of Barrett's esophagus by 89, 93 and 91%, respectively.

It must, however, be remembered that differential diagnosis of inflammation, dysplasia and cancer only on the basis of staining is not possible. Therefore, after chromoscopy, a multiple targeted biopsy of the revealed pathological sections of the mucous membrane is shown (regardless of the organ examined).

Indications for esophageal chromoscopy: suspected Barrett's esophagus; control examination of patients with Barrett food to identify possible foci of dysplasia and cancer (primarily, patients from high-risk groups: squamous cell carcinoma of the esophagus, squamous cell carcinoma of the ENT organs in the anamnesis, achalasia of the cardia). Contraindications to the use of Lugol's solution - an allergic reaction to iodine, hyperthyroidism; side effects - allergic reactions, irritation of the pharynx (as a sensation of burning, tingling, painful sensations).

Methylene blue is a color that stains blue in the absorbent epithelial cells of the mucous membrane of the small and large intestine, areas of incomplete and complete intestinal metaplasia in the esophagus and stomach, in addition to the metaplasia of the cylindrical epithelium of the cardial type. The main indication for the use of this dye is the diagnosis of Barrett's esophagus.

Methylene blue does not stain unchanged flat multilayered epithelium of the esophagus, however, dysplasia and cancer inside the actively absorbing epithelium are not uniformly or uniformly uniformly colored. As a rule, after staining the mucous membrane at the Barrett's esophagus, a mosaic pattern is revealed from the cylindrical epithelium of the cardiac type and intestinal metaplasia. It should be remembered that Barrett's cancer develops mainly in the zone of localization of intestinal metaplasia.

To obtain full results in conducting chromoendoscopy with methylene blue, several variants of "preparation" of the mucous membrane of the esophagus and stomach are known before applying the methylene blue solution. Pre-purify the stomach of mucus, which can also be stained with methylene blue. For this 2 hours before the endoscopic examination, patients are recommended to take 1.5-2 g of drinking soda dissolved in 50 ml of warm water, then 1 hour before the test - 50 ml of 0.25% aqueous solution of methylene blue. After this, esophagogastroscopy (EGDS) is carried out according to the usual method. When carrying out an endoscopic examination, it is advisable to carefully evaluate the presence or absence of staining of the mucosa of the esophagus and stomach, to detect the intensity of staining, the location and boundaries of the stained areas of the mucous membrane of the stomach and esophagus.

According to another method of preparation of the gastric mucosa for patients carrying out chromoendoscopy, a solution of acetylcysteine is applied first to remove surface mucus, the duration of which is 2 minutes, then a 0.5% solution of methylene blue is applied. According to the following variant, chromoendoscopy with methylene blue can be successfully performed after spraying mucolytic solutions for washing mucus of the stomach, and also for removing excess dye.

The method of endoscopic chromoscopy using a 0.5% solution of methylene blue is quite informative, especially after the preparation of an endoscopist for such an investigation and with his persistent desire to identify and recognize the nature of pathological changes in the mucosa of the esophagus and stomach in each specific case.

When preparing a patient for esophageal chromoscopy instead of mucolytic (pronase), 20 ml (for every 5 cm of esophagus) of a 10% solution of N-asetylousteine can be sprayed through the catheter. Then it is expedient to introduce a 0.5% solution of methylene blue. Excess dye after 2 minutes should be washed with 50-120 ml of water or saline. Positive is the dyeing of the mucous membrane with the appearance of a blue or violet color, which persists despite the subsequent washing of surplus dye with saline or water. After this, an endoscopic examination of the examined organ and targeted biopsies of pathological sections of the mucous membrane are carried out.

The essence of the mucosal staining mechanism is the penetration of methylene blue to a considerable depth along the wider intercellular channels of the tumor tissue (in comparison with the unmodified mucosa). Spraying methylene blue over the mucous membrane leads to the coloration of blue areas of cancer, clearly distinguishing them from the background of the unpainted mucous membrane of the organ under investigation. It must be remembered that methylene blue can also stain intestinal metaplasia of the gastric mucosa.

Staining of the esophagus by methylene blue in the mucous membrane of the esophagus allows one to suspect the presence of a specialized cylindrical epithelium of the intestinal type against the background of the multilayered squamous epithelium of the esophagus (by histological examination of the fragments of targeted biopsies with positive staining of the mucosa), to detect dysplasia and / or early cancer from histological examination of fragments of targeted biopsies with a weak, non-uniform staining or in the absence of staining with the methylene blue region, localization tion specialized columnar epithelium on the mucosa of the esophagus).

Methylene blue selectively stains a specialized columnar epithelium, which allows to diagnose the Barrett's esophagus even in patients with very short lesion segments. With Barrett's esophagus, the accumulation of methylene blue by the cells can be focal or diffuse (more than 75-80% of the mucous membrane of the Barrett's esophagus is dyed blue). Most of the esophagus mucosa in patients with a long segment (more than 6 cm) with Barrett's esophagus usually stains diffusely.

Severe dysplasia or an endoscopically indeterminate adenocarcinoma from a visual examination via the endofibroscope in the Barrett's esophagus can be detected by histological examination of the materials of multiple targeted biopsies obtained from lighter staining areas on the blue background of dye accumulation by the mucosa of the esophagus. Reliable morphological signs of the mucous membrane of the esophagus Barrett - the presence in the mucosa of the esophagus of a specialized prismatic epithelium in the form of crypts or villi, covered with prismatic cells secreting mucus, and goblet cells (goblet cells). This method is more effective in differentiating benign and malignant lesions of the mucosa of the esophagus and stomach, in the complex use of solutions of methylene blue and Congo red for staining the mucosa.

In spite of the fact that methylene blue is a non-toxic compound, the duration of which is 3 minutes, it is still advisable to warn patients about the possibility of a day after the study of the appearance of blue-green colored urine and feces (side effect).

Toluidine blue is used as a 1% solution when examining patients with lesions of the mucosa of the esophagus and stomach. Before the chromoendoscopy (before staining with a 1% aqueous solution of toluidine blue), spraying is carried out on suspicious areas of the mucous membrane, where pathological changes are assumed, 1% acetic acid solution acting mucolytically, followed by washing out the excess of the dye.

Toluidine blue is used in a study of patients with Barrett's esophagus to identify areas of metaplasia in the esophageal mucosa. However, it should be remembered that when staining the mucosa of the esophagus with this dye, it is not possible to visually distinguish gastric metaplasia from the intestinal through the endofibroscope. Staining the periulcerous zone of the mucosa in blue can help differentiate the benign ulcer and ulcer "ulcerative" cancer.

Congo red is a ph-indicator. When carrying out a chromoendoscopic examination of the stomach, this dye is used in the form of 0.3-0.6% solution, while it can be used alone or in combination with methylene blue. In the examination of patients, these dyes are applied sequentially. First, the staining of the gastric mucosa is carried out by the Congo red to identify the mucosal atrophy zones with areas of the "dysregulated" mucosal relief. Then, the mucosa is stained with methylene blue to detect intestinal metaplasia, which accumulates the dye. Congo red as a 0.1% solution and 20 ml of a 5% solution of sodium bicarbonate are applied to the surface of the mucous membrane, then tetra-gastrin is injected intramuscularly, then after 15 and 30 minutes an endoscopic examination of the gastric mucosa is performed changes in color of the mucous membrane). Early gastric cancer is defined as a "bleached" area of the mucosa, which is not stained with the above two dyes.

Phenol red is used in the form of a 0.1% solution when carrying out a chromoendoscopy of the stomach. In endoscopic examination, a 1.1% solution of phenol red and 5% urea are distributed evenly over the surface of the gastric mucosa, the result is estimated after 2-4 minutes from the application of the dye. The clinical use of this dye is the detection of Helicobacter pylori (HP) contamination of the gastric mucosa, based on the ability to determine HP to increase the level of urease produced by HP. The change in color of the mucosa from yellow to red indicates the presence of HP, while the areas of gastric metaplasia do not change its color.

Indigocarmine is a dye that is not absorbed, but deposited in the recesses of the folds of the mucous membrane, which creates a contrasting surface. This improves the visibility of heterogeneity of the altered areas. Before chromoendoscopy with indigocarmine, the mucous membrane is washed with water to remove mucus, then 0.1-1% solution of indigo carmine is applied to the mucosa of the test organ, followed by endoscopic examination of the mucosa followed by (if necessary) targeted biopsies. Main indications for biopsies: detection or suspicion of early gastric cancer; the detection of atrophy of the villi of the duodenum with celiac disease; Detection of pathological changes in the mucosa of the esophagus.

The so-called "Zoom-endoscopy" (endoscopy with an increase) is suitable for examining patients for more accurate endoscopic revision of suspicious areas, especially after staining the mucosa. An increase in the contrast of the mucous membrane is possible due to the preliminary application of acetic acid (before staining) to the mucous membrane.

Unfortunately, according to our observations, with chromoendoscopy, it is not always possible to obtain more information about the state of the human gastrointestinal tract than in a conventional endoscopic study. Obviously, therefore, after visual examination of the mucous membrane of the gastrointestinal organ under examination, it is recommended to perform a targeted biopsy to obtain a material for histological or cytological examination. To some extent, a certain "negative" attitude of endoscopists to chromoscopy is due to the need to involve additional medical personnel, which leads to an increase in the duration of endoscopic examination of patients.

Prof. Yu. V. Vasiliev. Chromoendoscopy of the esophagus and stomach // International Medical Journal - №3 - 2012

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