I.1.2. Gastroscopy

Dra. Ana Echarri Piudo
Complejo Hospitalario Universitario de Ferrol

 

INTRODUCTION

Upper gastrointestinal endoscopy or gastroscopy permits exploration of the digestive tract from the oral cavity to the second part of the duodenum.

To perform a gastroscopy, a front-view video gastroscope with wide-angle vision is used (between 140º–150º for more recent endoscopes), and the latest models come with a high-definition video imaging system (1.4 million pixels)1,2.

Standard gastroscopes used in daily practice have an insertion tube with an external diameter that is less than 10 mm and a working channel of 2.8 mm that enables the insertion of regularly used working materials such as biopsy forceps, polypectomy snares or injection needles (Fig. 1).  For certain particular situations, special models are available such as a therapeutic gastroscope with a 3.8–4.2 mm working channel that is necessary for prosthesis placement (Fig. 2), a double-channel gastroscope (at least one large channel), which enables the simultaneous insertion of two working materials (Fig. 3) or a small or paediatric gastroscope, which is very useful in stenosis passage, with an insertion tube diameter of 5.8–8.5 mm and a 2.2 mm 3.4 working channel.

 
FIGURA 1. Gastroscopio estándar. Dimensiones de tubo de inserción y canal de trabajo.
 
FIGURA 2. Gastroscopio terapéutico. Dimensiones de tubo de inserción y canal de trabajo.
 
FIGURA 3. Gastroscopio de doble canal con inserción de dos materiales de trabajo.
 

PATIENT PREPARATION

The endoscopist will take into account the essential and general aspects of all procedures such as the patient informed consent or sedation for performing the test, which are not included in this book5,6.

The patient must be fasting for 8 hours and not smoking. If the patient has dentures, they will be removed before the procedure.

The subject is placed in the left lateral position with a cushion under his or her head, and with the chin tilted towards the chest, which facilitates entry of the endoscope. A mouthguard will be placed between the teeth to protect the endoscope1.

The use of topical pharyngeal anaesthesia can enable entry of the gastroscope by inhibiting the nausea reflex7.

 

TECHNIQUE

The endoscope is generally introduced under direct view towards the upper oesophageal sphincter; at this time, the patient is asked to swallow, helping to slightly push its entry into the oesophagus.

1. The procedure begins with a careful examination of the mucous membrane of the oesophagus, while the gastroscope is being slowly introduced to the distal oesophagus and the oesophagogastric junction, passing through the cardia to the stomach.  The oesophagogastric junction corresponds to the transition line or Z-line, where the oesophageal mucosa (flat and pink, consistent with squamous epithelium) changes into the cardial mucosa, from a darker colour to an orange tone. The cardia is the short stomach segment that surrounds the oesophagogastric junction.

2. A stomach examination entails a systematic sequence of manoeuvres, which allow the visualisation of all gastric segments, including the areas that remain hidden during endoscope insertion. It is better to examine the stomach after the duodenal exam to prevent excessive gastric insufflation.

3. Advancing towards the duodenum is achieved by gently introducing the gastroscope, following the greater gastric curvature using a 60º–80º clockwise rotation and lower movement, meeting the pylorus and passing over it with light pressure. Insufflation, along with slight in-out movements, enables visualisation of the duodenal bulb; moving towards the right of the endoscope, rotating it 90º clockwise, allows passage through the duodenal knee until the 2nd area is reached; straightening the endoscope by the pull-out method with a 120º–180º clockwise rotation allows for insertion of the endoscope up to the distal duodenum. From the duodenal knee, one can observe the regular, circular duodenal fold characteristics, allowing for the visualisation of the characteristic mucosal villi via high-definition gastroscopes. The duodenal papilla, with the opening of the biliary and pancreatic ducts, is located in the inside of the second part of the duodenum and is generally recognizable due to its vertical fold characteristic, although it is usually necessary to use a lateral view endoscope or duodenoscope for proper exploration.

4. After duodenal exploration, the gastroscope is moved to the stomach, where the entire circumference of the antrum and gastric body is observed by rotating the gastroscope on its axis. With the gastroscope in its normal position, the anterior side of the stomach corresponds to the left part of the image and the posterior corresponds to the right, with the lesser gastric curvature appearing in the upper part of the image and the greater curvature in the lower part. The antrum is characterized by the absence of gastric folds, which is typical of the gastric body.

5. The gastric fundus must be examined via the retroversion manoeuvre. This is done from the position of the gastroscope in the middle area of the antrum, by bending it up while advancing it towards the pylorus, which allows for the visualisation of the angular incisure and lesser curvature. With the removal of the endoscope from this position, maintaining a 180º counter-clockwise rotation, we penetrate the fundus in retrograde motion, examining the cardial gastric aspect and gastric fornix.

6. From there, the endoscope is moved towards the oesophagus, after air and fluid suctioning, and the proximal oesophagus is properly evaluated during the removal8,9.

 

 

REFERENCES

1. Classen M, Tytgat G, Lightdale C, editors. Upper Gastrointestinal Endoscopy. In: Gastroenterological Endoscopy. 2nd ed. Stuttgart: Thieme; 2010.
2. Classen M, Tytgat G, Lightdale C, editors. Advanced Imaging in Endoscopy. In: Gastroenterological Endoscopy. 2nd ed. Stuttgart: Thieme; 2010.
3. Cotton P, editor. Pediatric Gastrointestinal Endoscopy. In: Advanced Digestive Endoscopy: Practice and Safety. Melbourne: Blackwell Publishing; 2008.
4. Cotton P, editor. Endoscopic Equipment. In: Advanced Digestive Endoscopy: Practice and Safety. Melbourne: Blackwell Publishing; 2008.
5. Classen M, Tytgat G, Lightdale C, editors. Informed Consent for Gastrointestinal Endoscopy. In: Gastroenterological Endoscopy. 2nd ed. Stuttgart; Thieme: 2010.
6. De la Morena E, Cacho G, editors. Sedación en Endoscopia Digestiva. Barcelona: Edimsa; 2011.
7. Bordas JM, Herráiz M, Brullet E, editors. Utilidad de la anestesia tópica faríngea en endoscopia digestiva alta. In: Actualizaciones en Endoscopia Digestiva 1. Barcelona: Edimsa; 2012.
8. Cotton P, Williams C, editors. Diagnostic Upper Endoscopy Techniques. In: Practical Gastrointestinal Endoscopy. The fundamentals. 5th ed. Melbourne: Blackwell Publishing; 2003.
9. Vázquez JL, editor. Endoscopia digestiva alta. In: Endoscopia digestiva. Diagnóstica y terapéutica. Madrid; Editorial Medica Panamericana: 2008.

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