Esophagogastroduodenoscopy (EGD) is a procedure during which a small flexible endoscope is introduced through the mouth (or, with smaller-caliber endoscopes, through the nose) and advanced through the pharynx, esophagus, stomach, and duodenum. An enteroscope, a longer endoscope, can be introduced beyond the ligament of Treitz into the jejunum.
EGD is used for both diagnostic procedures and therapeutic procedures. Most modern endoscopes now use a video chip (charged coupled device) for better imaging, as opposed to the older endoscopes, in which fiber optics are used for image transmission. (See the images below.)
In the United States, the procedure is usually performed while the patient is under conscious or moderate sedation, though it can be performed with only topical anesthesia (as is common practice in Europe and Asia). General anesthesia is often used in a selected group of patients who are difficult to sedate because of chronic narcotics intake.
The procedure is usually performed in a dedicated endoscopy unit in the hospital or outpatient office setting but can also be done in the emergency department (ED), the intensive care unit (ICU), or the operating room (OR) by using portable endoscopy carts. With the aid of various types of equipment and endoscopes, endoscopic ultrasonography (EUS), endoscopic retrograde cholangiopancreatography (ERCP), and small-bowel enteroscopy can also be performed.
Indications for EGD include the following  :
Diagnostic evaluation for signs or symptoms suggestive of upper gastrointestinal (GI) disease (eg, dyspepsia, dysphagia, noncardiac chest pain, or recurrent emesis)
Surveillance for upper GI cancer in high-risk settings (eg, Barrett esophagus  or polyposis syndromes)
Biopsy for known or suggested upper GI disease (eg, malabsorption syndromes, neoplasms, or infections)
Therapeutic intervention (eg, retrieval of foreign bodies, control of hemorrhage, dilatation or stenting of stricture, ablation of neoplasms, or gastrostomy placement)
Contraindications for EGD include the following:
Medically unstable patients
Anticoagulation, pharyngeal diverticulum, or head and neck surgery (relative contraindications)
Diagnostic EGD is considered a low-risk procedure for bleeding in patients on anticoagulants and therefore can be performed without adjustment of anticoagulants before the procedure.  However, if polypectomy is contemplated or conceivable, then the patient's coagulation profile should be normalized. A risk of retropharyngeal hematoma also may be present in patients with severe coagulation abnormalities.
Certain therapeutic procedures (ie, dilations, percutaneous endoscopic gastrostomy [PEG], polypectomy, endoscopic sphincterotomy, EUS-guided fine-needle aspiration [FNA], laser ablation, and coagulation) are considered high-risk procedures for bleeding, and adjustment of anticoagulation may be necessary.
Endoscopy units are specific areas in a hospital (or physician's office) in which all endoscopic procedures are performed. For this unit to be functional and effective, according to the American Society for Gastrointestinal Endoscopy (ASGE), certain conditions must be met, [4, 5] including the following:
Properly trained endoscopist and nursing staff
Functioning and adequately maintained equipment
Availability of an endoscope cleaning area
Personnel trained to perform cardiopulmonary resuscitation
Quality improvement program in place
Open access endoscopy is a system designed to offset the cost of endoscopy in stable patients without significant comorbidities who have clear indications for upper GI endoscopy.  The responsibilities of the referring physician are complete understanding of the patient's condition and the accepted indications for endoscopy. If the patient is on anticoagulation or if antibiotic prophylaxis is required, these issues must be addressed via proper communication between the referring physician and the endoscopist.
According to ASGE recommendations, training in upper GI endoscopy should include an understanding of indications, limitations, contraindications, alternatives, principles of conscious sedation, and correct interpretation of endoscopic findings.  A minimum of 100 upper GI endoscopic procedures is recommended for trainees to become competent in diagnostic upper GI endoscopy.
Therapeutic upper GI endoscopy requires further training and experience to gain competency. The recommendations of the ASGE for the number of procedures required to gain competency in various therapeutic upper GI endoscopic procedures are available through the society Web site (see American Society for Gastrointestinal Endoscopy).
Transnasal EGD (TN-EGD) has certain limitations in bending, which can make approaching certain gastric regions difficult. Rhee et al evaluated whether the quality and quantity of two-directional TN-EGD biopsied gastric specimens were affected by this limitation.  Specimen quantity was assessed on the basis of diameter and depth (μm), as well as presence of tissue layers (superficial mucosa, deep mucosa, muscularis mucosa, and submucosa). Specimen quality was assessed on the basis of anatomic orientation (good, intermediate, or poor), presence of crush artifact (none to minimal, mild, or moderate), and overall diagnostic adequacy (adequate, suboptimal, or inadequate).
Of 289 TN-EGD gastric biopsy specimens, 33 (11.4%) were of poor orientation, 26 (9.0%) revealed the presence of crush, and 37 (12.8%) demonstrated overall diagnostic inadequacy.  In 211 (73.0%), deep mucosa was present, but only 75 specimens (26.0%) had muscularis mucosa. The posterior aspect of the cardia had the greatest limitations in specimen quantity and quality, with the shallowest depth, poorest orientation, and poorest diagnostic adequacy. The investigators recommended paying special attention to gastric lesions located on the posterior aspect of the cardia when using two-directional TN-EGD.
In a two-part study, Japanese investigators attempted to find a good washing solution to counter the known limitations of the small-caliber water-jet nozzles of TN-EGDs for cleaning lenses.  Komazawa et al compared oolong tea, barley tea, and distilled water as washing solutions for the endoscopic lenses. In the first part of the study, the TN-EGD lenses were soiled by lard and then washed with one of the three washing solutions. When the image quality of photographs were judged, lenses washed with oolong tea resulted in a significantly higher image quality than did lenses washed with barley tea or distilled water solutions.
In the second part of the study, 982 patients scheduled to undergo TN-EGD were randomly assigned to groups in which the endoscope lens was washed with one of the three washing solutions. The investigators found that the level of lens cleansing was significantly greater and the overall time required for endoscopy was significantly shorter in the oolong tea group than in the other two groups.  When the volume of washing solution used for lens cleansing was compared, significantly less was used in the oolong group compared with the distilled water group. On the basis of their findings, Komazawa et al recommended oolong tea rather than water for cleaning TN small-caliber EGD lenses.
Despite the large number of endoscopic procedures performed each day, the incidence of infection transmission via endoscopes remains very low.  Methods of reprocessing endoscopes include mechanical cleaning, high-level disinfection, rinsing, and drying. Proper and diligent care during reprocessing of endoscopes, with attention to quality control, cannot be overstated for minimizing the risk of spreading infection via endoscopic procedures.