Role of Endoscopy in Diagnosing GERD & Barrett’s Esophagus



Role of Endoscopy in Diagnosing GERD & Barrett’s Esophagus

• Gastroesophageal reflux is a normal physiological phenomenon experienced intermittently by most people, particularly after a meal.

• GERD describes any symptomatic condition or histopathologic alteration resulting from episodes of gastroesophageal reflux.

• Non-erosive reflux disease (NERD) describes endoscopy-negative patients with reflux symptoms and abnormal esophageal acid exposure during ambulatory 24-h esophageal ph monitoring.

• Functional heartburn describes endoscopy-negative patients with reflux symptoms and normal findings on ambulatory 24-h esophageal pH monitoring.

• Barrett’s esophagus is a complication of gastroesophageal reflux disease, it is clinically important not only as a marker of severe reflux, but also as a potential precursor of cancer of the esophagus.

• Diagnostic upper endoscopy in GERD may reveal either a normal or an abnormal esophagus characterized by ulcers, erosions, exudates, and friability.

• There are four widely used systems for grading the severity of the esophageal damage, the Los Angeles, the Savary–Miller, the Hetzel–Dent, and the MUSE classification.

Los Angeles Classification

Grade A: one or more areas of tissue loss, not exceeding 5 mm.

Grade B: one or more areas of tissue loss, exceeding 5 mm but without confluence in between the folds.

Grade C: one or more erosions extending over two or more folds but not involving the circumference of the lumen.

Grade D: circumferential tissue loss.

Savary Miller Classification

Stage 1: single or multiple, non-confluent, erythematous lesions, exudative lesions or superficial erosions.

Stage 2: confluent but not circumferential erosions or exudates near the Z-line.

Stage 3: confluent and circumferential erosions and exudative lesions with involvement of the wall but without stricture.

Stage 4: chronic fibrosis, esophageal ulcer or stricture.

Stage 5: Barrett’ esophagus.

Hetzel Dent Classification

Grade 0: normal mucosa.

Grade 1: mucosal edema, hyperemia and friability.

Grade 2: superficial erosions involving less than 10% of the distal 5 cm of esophageal mucosal surface.

Grade 3: superficial erosions and ulcerations 10-50 % of distal esophagus.

Grade 4: deep peptic ulceration anywhere in the esophagus or confluent erosion of more than 50 % of the distal esophagus.

MUSE Classification

This system is analogous to the TNM classification system used in oncology and describes several independent features: metaplasia (M), ulceration (U), stricture formation (S), and mucosal erosion (E). Each of these elements is graded independently in four increments (0, absent; 1, mild; 2, moderate; 4, severe). The result of an endoscopic examination is described as a grade for each lesion type, i.e. M0U1S0E1.

• An endoscopy report for a GERD patient should grade the degree of esophagitis, describe the extent of BE (if present), locate the GEJ in centimeters from the incisors.

• It is also important to measure the distance if any between the Z-line and the diaphragmatic hiatus. Normally, this distance should be 0–2 cm; otherwise a sliding hiatal hernia is present.

What’s New ?

• A catheter-free pH monitoring System, Bravo System.

• Placed 6 cm above the squamocolumnar junction.

• Records pH every 6 s and transmit it to a pager-sized receiver worn by the patient for 48 hrs.

• Endoscopic measurement of cardia circumference as an indicator of GERD.

• Software to measure cardia circumference from static endoscopic images.

• By using 34.3 mm as a cutoff, Cardia circumference was 85.3% sensitive and 89.6% specific for the diagnosis of GERD.

Novel diagnostic techniques for Barrett's esophagus

Barrett’s Classifications

• Two criteria must be fulfilled to diagnose Barrett's:

• Proximal migration of SCJ & SIM on Histology.

• According to length:

• Long-segment BE (LSBE): > 3cm.

• Short-segment BE (SSBE): < 3cm.

• Ultra-short BE (USBE): microscopic.

• According to SIM: It’s called incomplete (Types II and III) because it is less well differentiated than the more mature intestinal metaplasia (IM) occurring at the squamo-columnar junction which is fully differentiated (Type I).

• According to extent of BE: C & M classification where C is the circular extension, M is the maximum extension.

• According to Mucosal Pattern in Chromoendoscopy: Several classifications exist depending on the stain used.

Chromoendoscopy

• It is the application of absorptive stains (Lugol's iodine solution, methylene blue, and toluidine blue) or contrast stain (Indigo carmine, Acetic acid) to enhance and improve the characterization of mucosal surfaces.

• Lugol's iodine: stains benign, glycogen-containing, non-keratinized squamous cells brown but does not stain dysplastic, inflamed, or malignant squamous cells or columnar mucosa.

• Methylene blue: stains actively absorbing intestinal-type cells but does not stain squamous and gastric cells or gastric-type metaplasia.

• Can be used either with the standard gastroscopes or the high resolution zoom gastroscopes.

• It is superior to random biopsy in diagnosing specialized Barrett’s epithelium that is greater than 1 cm (i.e. irregular Z line) and less than 3 cm.

• Indigo carmine: is a blue contrast stain not absorbed by cells; it pools in the crevices between mucosal projections and highlights subtle mucosal abnormalities.

• BE is visualized as a slightly raised surface pattern with a villiform appearance (similar to small intestinal mucosa).

• Acetic acid: produce whitening reaction in the squamous epithelium while the columnar epithelium becomes reddish and swollen with enhanced surface architecture.

• Can be used either with the standard gastroscopes or the high resolution zoom gastroscopes.

• Detect intestinal metaplasia and intraepithelial neoplasia in the esophagus.

Narrow Band Imaging

• New optical technique that uses red-green-blue light filters that enhance both the mucosal contrast and the vascular imaging.

• This system, in combination with magnifying endoscope, can yield very clear images of the microvessels on mucosal surfaces.

• No need for staining.

Magnification/High-resolution Endoscopy 

• Offers another way of improving the inspection of the esophageal epithelium.

• Magnification rates of up to × 150, and the high-resolution video endoscopes offer a 60–100% increase in resolution over the older models.

• These two modalities can be used either alone or in combination with chromoendoscopy.

Fluorescence Endoscopy (FE)

• Tissue fluorescence occurs when tissues are exposed to light with a short wavelength (usually ultra-violet or blue light) and certain substances (e.g., fluorophores) are excited, causing them to emit fluorescence light with a longer wavelength.

• Fluorophores can either be endogenous biological substances (e.g., collagen, aromatic amino acids, and porphyrins), or exogenously administered drugs such as 5-aminolevulinic acid (5-ALA).

• Three methods of applying the principles of FE in BE, Light induced fluorescence Endoscopy (LIFE), Laser-induced fluorescence spectroscopy (LIFS), and photodynamic diagnosis.

Light Induced Fluorescence Endoscopy (LIFE)

• Mucosa is illuminated with monochromatic blue light.

• Two cameras attached to the fiber-optic endoscope to detect red and green fluorescence.

• Normal esophageal epithelium appears green, BE appears a brick red and high-grade dysplasia appears a darker brick red.

• No Exogenous administration of fluorescence agent.

Optical Coherence Tomography (OCT)

• OCT is a cross-sectional imaging technique that provides the highest endoscopic resolution currently available.

• In vivo resolution of OCT imaging (~ 10 µm); ten times greater than that of high frequency ultrasound.

• Visualize subcellular structures including nuclei.

• Analogous to ultrasound but uses light waves (infrared) rather than acoustic waves.

• Resolution approaching that found in conventional histopathology, but without the need for tissue removal; thus it is termed “optical biopsy”.

Reflectance & Elastic Light Scattering Spectroscopy

• Measures the wavelength dependence of light that has entered the tissue, been scattered by numerous constituents (subcellular structures and tissue layers) within the tissue and re-emitted.

• Light scattering can provide structural and functional information about the tissue.

• Distinguish between dysplastic and non-dysplastic tissue based on differences in nuclear size, with malignant tissue displaying larger hyperchromatic nuclei, increased mitotic rates, and crowding.

Raman Spectroscopy (RS)

• Measures changes in specific energy states (i.e. vibrational and rotational energies) of the molecular bonds of atoms and molecules.

• Light energy (infra-red wavelengths) impinges on a biomolecule, exciting it to a higher rotational/vibrational state and, in doing so, emits light waves of typically longer wavelengths (lower frequency).

• RS can be used to distinguish between different tissues, or changes within a single tissue.

Confocal Microscopy

• Experimental method of studying the epithelium at the cellular and subcellular level.

• "Confocal" is defined as "having the same focus." What this means in the microscope is that the final image has the same focus as or the focus corresponds to the point of focus in the object.

• A thin probe is passed down the accessory channel of a fiber-optic gastroscope, and passes images up to a laser-scanning confocal microscope.

• Compete with histological analysis of epithelial substructure, and offers the potential for the development of a real-time optical biopsy system.

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