What is the Scope of Gastroscopy ?
Gastroscopy, (gastro- stomach; scopy-looking) is a diagnostic test that enables the doctor to look inside of the esophagus, stomach, and duodenum. This device has a length of approximately 1200 mm and diameter of 9.5-12.5 mm. The instrument shaft is composed of numerous specialized glass fibers(>30,000) which allow the transmission of light down the length of each thin fiber with minimal distortion. The multiple fiber optic images are integrated at the proximal eyepiece unit, by means of a complex system of lenses. The endoscopist thus views a reconstructed, mosaic image at the proximal eyepiece (similar to a television image). Also within the instrument shaft are several separate channels designed for passage of optional devices such as biopsy forceps, polyp snare, cytology brush, cautery or laser device, and suction. Air may also be introduced for insufflation's of the stomach. For clearing of debris from the viewing area, a jet stream of water from a separate reservoir can be flushed through one channel. At the head or handle of the endoscope are two control devices ("wheels") which maneuver the instrument tip as it is advanced, an up-down angle wheel (deflection of almost 180°) and a right-left angle wheel (deflection of 100°). The instrument head is connected with a separate cold light source (usually a halogen lamp) by means of a cable comprised of incoherent fiberoptic bundles (the "umbilical cord"). The water feed tank and automatic suction box also attach to this cable. Optional accessories include an additional eyepiece for simultaneous viewing by a second operator (the "teaching head"), an ultrasound probe for real time imaging of the stomach wall, pancreas, etc, and photographic or videotape recording devices. 

What is the Purpose of Gastroscopy ? 

High yield indications : 

• Acute upper GI bleeding, to establish the exact location of  hemorrhage prior to endoscopic cautery, surgery, etc. . Dysphagia, especially if esophageal strictures or ulcerations  are seen on a previous upper gastro intestinal series. 

• Dyspepsia, if refractory to standard medical antireflux therapy. EGD is also indicated whenever a surgical antireflux  procedure is planned. 

• Odynophagia, when inflammation or infection is clinically suspected, especially if esophagitis from Candida, cytomegalovirus, or herpes simplex virus is likely. 

• Surveillance endoscopy for known pre-malignant conditions, such as Barrett's esophagus, lye-induced strictures, Plummer-Vinson syndrome. 

• Abnormalities seen on upper GI series which require visual confirmation and tissue biopsy (eg, polyps, gastric ulcers, redundant gastric folds, strictures) 

• Suspected gastric outlet obstruction. 
  
  Lower yield indications : 
  1. Atypical chest pain. 
  2. Abdominal pain of unknown etiology. 
  3. Routine, uncomplicated cases of gastroesophageal reflux. 
  4. Uncomplicated cases of duodenal ulcer demonstrated by upper GI series. 
  
  Therapeutic indications for Endoscopy are numerous and include 
  1. Sclerotherapy of bleeding esophageal varices 
  2. Management of upper GI bleeding using electrocautery, photocoagulation, etc 
  3. Laser ablation of esophageal cancer. 
  4. Endoscopic placement of esophageal stints. 
  5. Placement of permanent feeding tubes under Endoscopic
     guidance (PEG tubes) 
  6. Dilatation of esophageal strictures. 
  7. Polypectomy 
  8. Dissolution of bezoars. 
  
  What are the Contraindications of Gastroscopy ? 
  1. Acute myocardial infarction 
  2. Hypoxemia with respiratory distress 
  3. Hypotension and shock, regardless of etiology. 
  4. Massive upper GI bleeding with hypotension where emergency surgery is clearly appropriate. 
  5. Uncontrolled hypertension. 
  6. Un co-operative patient. 
  
  
  The Preparation 
  An important examination requires proper preparation. The
   results obtained from this exam are dependent on the stomach being empty. Food particles inside the stomach can hide important conditions that may be present and may increase the risk of aspiration (choking) during the examination. 
  
  Morning of the Examination 
  The duodenum and stomach must be empty during gastroscopy so that the physician's view is not blocked by particles of food. If the test is scheduled in the morning, one must not eat or drink anything after midnight the night before the test. If the test is scheduled in the afternoon, the patient is placed on a liquid diet - such as juice, coffee, tea, or broth - for breakfast. Then begin fasting. The patient should not eat or drink anything for at least 6 hours before the exam. 
  
  Medication 
  The patient can continue to take any important medications that his physician has prescribed . Simply take them with a small sip of water at least two hours before your appointment. This allows time for the tablets to dissolve completely. Antacids should not be taken on the day of the test. Smoking should be avoided as tobacco changes the normal color of the stomach lining. 
  
  The Problems Encountered 
  1. Perforation of esophagus or stomach: Up to 0.1% of all Esophagogastroduodenoscopy's . The upper esophagus above the cricopharynx appears most vulnerable. Other risk factors are esophageal cancer, strictures, or cervical osteophytes. 
  2. Bleeding: Considered rare even after biopsies, at 0.3/1000 cases. In most cases, bleeding is not due to a coagulation defect, rather it results from biopsy of friable tissue. 
  3. Cardiopulmonary complications: Significant cardiac arrhythmias are distinctly unusual. If a Holter monitor is placed, transient rhythm disturbances such as sinus tachycardia, premature ventricular contractions (PVCs), premature atrial contractions (PACs), and rarely ischemic changes may be recorded in 22% of cases. Few adverse clinical outcomes have been reported. 
  4. Lung infections due to vomiting and aspiration during the procedure. 
  
  
  Limitations 
  Quality of study and its interpretation are highly dependent on the expertise of the endoscopist. Recognition of subtle abnormalities and visualization of all portions of the upper gastro intestinal tract require a high degree of clinical competence. A variety of technical factors may lead to a suboptimal study. Endoscopists refer to "blind spots" - regions difficult to visualize in most cases - which include the superior aspect of the duodenal bulb, portions of the fundus, and the lesser curvature below the incisura. Active uncontrolled bleeding, retained blood in the stomach, and retained food or antacids may also lead to an inadequate study. EGD should not be used for the diagnosis of esophageal motility disorders. Similarly, EGD is not a first-line test for the diagnosis of reflux esophagitis.