Gastroscopy

• Examination of the gastric mucosal surface.
• Collection of gastric mucosal biopsy samples.
• Detection and retrieval of gastric foreign bodies Stomach: gastric foreign body.
• PEG tube placement Gastrostomy: percutaneous tube (endoscopic).
• Investigation of:
  • Vomiting Vomiting.
  • Hematemesis.
  • Gastric neoplasia.
  • Chronic gastritis Chronic gastritis.
  • Gastric ulceration.
  • Pyloric outflow disorders.

Advantages

• Non-invasive technique requiring no surgical intervention.
• Well tolerated by sick cats which would be unsuitable for laparotomy.
• Requires only light general anesthesia - rapid recovery.
• Good visualization of the gastric mucosa.
• Follow up examination well tolerated and useful for to assessing response to treatment

Disadvantages

• Will not detect pathology lying under the mucosa.
• Cannot carry out surgical correction compared with laparotomy.
• Expensive equipment.

• Technical difficulty in procedures.

• Radiography Radiography: abdomen and fluoroscopy contrast studies (barium series) fluoroscopy of the alimentary tract.
• Exploratory laparotomy Laparotomy: midline.
• Ultrasonography: detection of submucosal lesions and muscular hypertrophy. Gas can hamper evaluation.

Preparation

• Induction of anesthesia and/or sedation   →   10-30 min.

Procedure

• Depends on the experience of the endoscopist   →   approximately 15-30 min.

Risk assessment

• Low risk.
• See complications.

Nursing expertise

• Good level of competence required for assisting in procedures, monitoring anesthetic and assisting in biopsy collection and handling.
• High competence for care and cleaning of endoscopic equipment

Minimum equipment

• Fully immersible fiber optic flexible endoscope.
• Insertion tube diameter 6-8 mm.
• One meter insertion tube length.
• ONLY use an end viewing endoscope.
• Four way tip deflection.
• MUST have cold light source with air pump and water wash facility.
• Fenestrated biopsy forceps for collection of mucosal biopsy samples.
• Cleaning brushes for biopsy channels.
• Water leakage tester.

Ideal equipment

• Video endoscope:
  • Excellent magnified image presented on screen.
  • Detection of lesions much easier.
  • Allows for multiple person viewing.
  • Excellent for video recording procedures and/or collecting still images.
  • Excellent as a training aid.
• Xenon light source.
• Insertion tube diameter 6-8 mm.
• Suction unit for aspiration of unwanted gastrointestinal secretions and air.
• Cytology brushes, grasping forceps and balloon catheters.
• More than one endoscope for examination of different parts of the gastrointestinal tract.
• Endscope cleaning cart.
• Ultrasonic cleaner for biopsy forceps.

Minimum consumables

• Clean water.
• Endoscope cleaners and disinfectants.
• Household detergent.
• Formal saline, card and containers for preservation of biopsy samples.

Other requirements

Care and maintenance

• Storage of endoscopes:
  • ALWAYS store endoscopes in a safe location where accidental knocks can be avoided.
  • ALWAYS store endoscopes with insertion tube hanging vertically.
  • Do NOT store endoscopes in their carrying case.
  • See supplier for further details of endoscope 'hangers'.
• Cleaning and disinfection Endoscope: cleaning:
  • Follow the manufacturers recommendations at all times.
  • Use an endoscope cleaning bath wherever possible.
  • Use whatever cleaners and disinfectant the manufacturer recommends.
  • Follow health and safety rules regarding use of these products.

• Suitable premedication.

• Nil by mouth for a minimum of twelve hours, longer if there is delayed gastric emptying.

• General anesthesia.

Step 1 - Pass tube along esophagus

• Following induction of anesthesia - it is essential to intubate patient.
• Tie endotracheal tube to mandible to aid passage of endoscope.
• Lay patient in left lateral recumbancy.
• Place mouth gag to protect endoscope.
• Pass endoscope.
• Insert endoscope along hard palate and into proximal esophagus .
• Advance scope along length of esophagus (see Esophagoscopy Esophagoscopy).

Step 2 - Enter stomach

• Once cardia is reached   gently apply force on endoscope to enter stomach.
• 'Red out' will occur during intubation of stomach. (Vision is lost).
• Once you feel the endoscope pass the cardia, STOP, gently inflate stomach with air.

Step 1 - Examine rugae

• Only introduce enough air to visualize the mucosa.
• It is very important NOT to overdistend the stomach with air.
• Examine the rugal folds of the fundus   .

Step 2 - Examine antral region

• Advance endoscope in the direction of the rugal folds. This will direct you towards the antrum.
• The angular incisure of the lesser curvature of the stomach will be seen as a band of mucosa and marks the entrance to the antrum   .
  This is an important endoscopic landmark.Rugal folds are NOT seen if stomach is overinflated with air.
• Retroflex the endoscope to visualize the cardia   .

Step 3 - Examine pylorus

• Pass endoscope along antrum to visualize the pylorus      .
• Bile may be observed entering the stomach as may antral peristaltic contraction.
  These contractions are not seen if the stomach is overinflated.

Step 4 - Biopsy

• Collect biopsy samples from any focal lesions observed.
• In any case collect biopsy samples from the fundus, body, cardia and antrum.
• A minimum of 6 biopsy samples are required.
  Always deflate the stomach with the endoscopic suction unit or stomach tube after the procedure.
• Do not overinflate the bowel as this will make mucosa stretch tightly reducing ability to collect samples.
• Try and advance biopsy forceps perpendicular to the mucosa.
• Tent mucosa before closing biopsy forceps and retrieving sample.
• Deeper samples can be collected by sampling repeatedly at the same site.
• Perforation will occur if this is done too frequently.
• Capillary bleeding from biopsy sites is normal.

Step 1 - Remove endoscope

• Gently withdraw endoscope.
• Support end of scope as it is withdrawn to prevent damage.

General Care

• Routine post-anesthetic observation.
• Check mucus membrane color, heart and respiratory rates in case of hemorrhage.
• Check there is no evidence of gastric dilation.

Special precautions

• Do not overinflate stomach.
• Apply only enough air to allow adequate visualization.
• Always deflate the stomach after gastroscopy to reduce risk of gastric dilation.

Potential complications

• Arterial bleeding from biopsy sites.
• Gastric perforation from applying too much force.
• Iatrogenic damage to mucosa caused by advancing endoscope along gastric wall.

Refereed papers

• Recent references from PubMed and VetMedResource.

Other sources of information

• Tams T R (1998) Small Animal Endoscopy. 2nd edn. C V Mosby, St Louis.
• Simpson J W (1996) Gastrointestinal Endoscopy. In: Manual of Canine and Feline Gastroenterology. Eds: D Thomas, J W Simpson, E J Hall. BSAVA, Cheltenham. pp 20.
• Brearley M, Cooper J E, Sullivan M (1991) A Colour Atlas of Small Animal Endoscopy. Wolfe.