INTRODUCTION — Upper gastrointestinal endoscopy (esophagogastroduodenoscopy, EGD) includes visualization of the oropharynx, esophagus, stomach, and proximal duodenum, with real-time assessment and interpretation of the findings encountered. A variety of technical and cognitive aspects must be mastered in order to perform a high-quality examination. The basic technical components of upper endoscopy also serve as the platform upon which many therapeutic interventions are based.

The elements of high-quality performance in endoscopy have been well described and include the following [1,2]:

Prior to the procedure:

●Appropriate indications and adherence to guidelines

●Suitable environment with adequate support team

●Strategies to minimize risk, including patient preparation and monitoring

●Well-prepared, informed, and consented patients

●Correct selection of equipment

During the procedure:

●Appropriate use of sedation/analgesia

●Comfortable oral and esophageal intubation with the endoscope

●Complete assessment of target organ(s)

●Recognition and documentation of all abnormalities

●Proper tissue sampling

●Use of appropriate therapy where indicated

●Avoiding, recognizing, and managing complications

●Reasonable procedure duration

After the procedure:

●Smooth recovery, explanation of procedure, and discharge

●Integrated pathology results

●Clear recommendations and follow-up plan

This topic will review factors associated with performing an upper endoscopy including indications, patient preparation, technical aspects, tissue sampling, and complications. Detailed discussions of specific diagnostic and therapeutic interventions carried out during an upper endoscopy and special considerations for upper endoscopy in the setting of the COVID-19 pandemic are presented separately. (See "Endoscopic interventions for nonmalignant esophageal strictures in adults" and "Methods to achieve hemostasis in patients with acute variceal hemorrhage" and "Overview of the treatment of bleeding peptic ulcers" and "Barrett's esophagus: Surveillance and management" and "Overview of the treatment of achalasia" and "Overview of endoscopic resection of gastrointestinal tumors" and "COVID-19: Issues related to gastrointestinal disease in adults", section on 'Implications for endoscopy'.)

PATIENT SELECTION — The first step in upper endoscopy is appropriate patient selection. Patient selection must take into account not only the indication(s) for the procedure, but also patient-related factors such as comorbid illnesses that might increase the risk of performing an upper endoscopy or make the examination more difficult.

Indications — An upper endoscopy is indicated in the diagnostic evaluation of signs and symptoms of a wide variety of gastrointestinal (GI) disorders (table 1). In addition, there are multiple therapeutic indications for upper endoscopy.

In 2012, the American Society of Gastrointestinal Endoscopy (ASGE) issued guidelines regarding the performance of upper GI endoscopy [3]. In general, they recommend upper endoscopy if the results are likely to influence management of the patient, if empiric treatment for a suspected benign disorder has been unsuccessful, if the procedure can be used as an alternative to radiographic evaluation, or if a therapeutic maneuver may be needed. In addition, upper endoscopy is indicated if the results would affect the management of other diseases (eg, a patient with a history of upper GI bleeding who requires anticoagulation or treatment with a nonsteroidal antiinflammatory drug). The ASGE issued a second guideline in 2015 specifically addressing the role of upper endoscopy for patients with gastroesophageal reflux disease (GERD) [4]. In patients with GERD, upper endoscopy was recommended to evaluate patients with symptoms suggestive of complicated GERD or alarm symptoms, for follow-up of patients with severe esophagitis to rule out underlying Barrett's esophagus, and to screen for Barrett's esophagus in patients with multiple risk factors. (See "Medical management of gastroesophageal reflux disease in adults", section on 'Pretreatment evaluation' and "Barrett's esophagus: Epidemiology, clinical manifestations, and diagnosis", section on 'Epidemiology'.)

The ASGE guidelines note that upper endoscopy is generally not indicated when the results will not affect management or for periodic surveillance of healed benign lesions, unless surveillance of a premalignant condition is warranted.

Diagnostic examinations — Many upper endoscopies are carried out for the evaluation of symptoms or to investigate abnormal findings on GI tract radiology.

●Upper gastrointestinal symptoms – Upper endoscopy is indicated for the evaluation of patients with upper abdominal symptoms (eg, pain, nausea) that persist despite an adequate trial of therapy, whose symptoms are associated with other signs or symptoms that suggest serious organic disease such as weight loss, or who are over the age of 50 years. Upper endoscopy is also indicated for the evaluation of dysphagia, odynophagia, esophageal reflux that is persistent or recurrent despite adequate therapy, persistent vomiting of an unknown cause, or diarrhea thought to be due to small bowel disease. (See "Approach to the adult with dyspepsia".)

●Upper gastrointestinal bleeding – Active or recent upper GI bleeding is another indication for upper endoscopy. In addition, upper endoscopy should be considered for patients with chronic blood loss and iron deficiency anemia with a clinically suspected upper GI source or if a colonoscopy is negative. (See "Approach to acute upper gastrointestinal bleeding in adults", section on 'Upper endoscopy' and "Evaluation of suspected small bowel bleeding (formerly obscure gastrointestinal bleeding)" and "Evaluation of occult gastrointestinal bleeding", section on 'Upper endoscopy'.)

●Abnormal imaging – Upper endoscopy is indicated for the evaluation of lesions seen on upper GI tract radiology (eg, suspected neoplasms, ulcers, strictures or obstructions). However, upper endoscopy is generally not indicated for the evaluation of asymptomatic or uncomplicated sliding hiatus hernias, radiologically demonstrated duodenal ulcers that respond to ulcer therapy, or the finding of a deformed duodenal bulb that is asymptomatic or has responded to ulcer therapy.

Caustic ingestions — Patients with acute caustic ingestions should undergo upper endoscopy to assess the degree of injury. (See "Caustic esophageal injury in adults", section on 'Subsequent management'.)

Screening/surveillance — It is recommended that patients with Barrett's esophagus undergo endoscopic surveillance [5]. This recommendation is based upon the assumptions that Barrett's esophagus adversely influences survival and that surveillance can reduce mortality. However, a survival benefit in patients undergoing surveillance has not been demonstrated in randomized prospective trials. (See "Barrett's esophagus: Surveillance and management", section on 'Surveillance'.)

Upper endoscopy can be used to screen patients for gastric cancer, though consensus has not been achieved on screening recommendations. However, some form of screening has been proposed in several subgroups of patients in whom the risk of gastric cancer is particularly increased [6]. These include older adult patients with atrophic gastritis or pernicious anemia, those who have undergone partial gastrectomy [6,7], those with a sporadic gastric adenoma [8], immigrant ethnic populations from countries with high rates of gastric cancer (table 2) [7,9-16], and patients with familial adenomatous polyposis or hereditary nonpolyposis colorectal cancer (particularly if gastric cancer has occurred in the kindred) [17]. (See "Gastric cancer screening" and "Familial adenomatous polyposis: Screening and management of patients and families" and "Lynch syndrome (hereditary nonpolyposis colorectal cancer): Cancer screening and management".)

Upper endoscopy is also used to screen patients with portal hypertension for the presence of esophageal varices and to screen patients with a history of a caustic ingestion for esophageal squamous cell carcinoma. (See "Primary and pre-primary prophylaxis against variceal hemorrhage in patients with cirrhosis", section on 'Screening for varices' and "Caustic esophageal injury in adults", section on 'Complications'.)

Planned therapeutic intervention — Therapeutic indications for upper endoscopy include (see 'Diagnostic and therapeutic maneuvers' below):

●Treatment of bleeding lesions (ulcers, angiodysplasias, varices)

●Prophylactic banding of esophageal varices

●Removal of foreign bodies

●Placement of feeding or drainage tubes

●Removal of selected polypoid lesions (see "Gastric polyps")

●Dilation of stenotic lesions

●Management of achalasia

●Palliation of stenosing neoplasms

●Endoscopic therapy of intestinal metaplasia

●Management of operative complications (eg, anastomotic strictures)

Contraindications — As with any procedure, patients in whom the risks of upper endoscopy are believed to outweigh the benefits should not undergo the procedure. Other contraindications include the inability of the patient to cooperate with the procedure despite adequate attempts at sedation/anesthesia, an inability to obtain informed consent, or the presence of a known or suspected perforated viscus (unless the examination is being done to treat the perforation). Failure to comply with dietary restrictions prior to endoscopy is a relative contraindication. (See 'Diet' below.)

One question that often comes up is when is it safe to perform an upper endoscopy in a patient who has had a recent myocardial infarction (MI). In a patient who needs an urgent/emergent endoscopy (eg, overt upper GI bleeding), endoscopy should not be delayed in a hemodynamically stable patient with a recent MI. A decision analysis suggests that this approach is preferable to proceeding with cardiac catheterization in patients with overt (but not occult) GI bleeding [18].

With regard to elective procedures, there are no firm recommendations. The American Heart Association recommends waiting 60 days for noncardiac surgery following an MI if the patient has not undergone coronary revascularization [19]. The recommendation is to wait 14 days after balloon angioplasty and 30 days after bare metal stent implantation. If a drug-eluting stent is inserted, elective noncardiac surgery should be delayed 365 days, if possible (180 days if the risk of delay is greater than the risk of ischemia and stent thrombosis). One factor that complicates endoscopy in this setting is that patients are likely to be taking antiplatelet agents. The management of these agents around the time of endoscopy is discussed in elsewhere. (See "Management of antiplatelet agents in patients undergoing endoscopic procedures" and "Noncardiac surgery after percutaneous coronary intervention", section on 'Our approach'.)

Whether the procedure is emergent or elective, decisions regarding the timing of endoscopy and the management of antiplatelet agents in such patients should involve both the gastroenterologist(s) and cardiologist(s) caring for the patient.

Important considerations — Prior to the procedure, patients should be evaluated for other factors that may affect the ability to safely and successfully perform an upper endoscopy, including:

●Anatomic considerations such as a small mouth or a limited range of motion in the jaw (factors that may make it difficult to insert the protective mouth piece), a limited range of motion of the neck that may make correct patient positioning difficult, or the presence of a Zenker's diverticulum, which increases the risk of esophageal perforation during esophageal intubation.

●Comorbid illnesses that may increase the risks associated with sedation.

●Use of medications such as benzodiazepines or narcotics that may increase a patient's tolerance to the effects of sedation.

PATIENT PREPARATION

Diet — Prior to elective upper endoscopy, patients typically take no food by mouth for four to eight hours, and sometimes longer if there is known or suspected delayed gastric emptying [20]. Alternatively, clear liquids can be taken up to two hours before endoscopy (American Society of Anesthesiologists guidelines [21]).

Medications — Most medications can be continued up to the time of endoscopy and are usually taken with a small sip of water. Some medications may need to be adjusted prior to upper endoscopy, such as medications for diabetes, due to decreased oral intake around the time of the procedure.

Management of anticoagulants — Decisions regarding the management of antiplatelet agents or anticoagulants must take into account the risk of bleeding engendered by maintaining the patient on the agent through the procedure and the risk of a thromboembolic event if the agent is discontinued in the periprocedural period [22]. In general, aspirin and nonsteroidal antiinflammatory drugs can be continued safely in patients having an upper endoscopy. (See "Management of anticoagulants in patients undergoing endoscopic procedures" and "Management of antiplatelet agents in patients undergoing endoscopic procedures" and "Gastrointestinal endoscopy in patients with disorders of hemostasis".)

Antibiotic prophylaxis — Guidelines exist for the use of antibiotic prophylaxis in endoscopy. Because the risk of infection related to routine diagnostic upper endoscopy is low, antibiotic prophylaxis is not recommended. However, antibiotic prophylaxis is recommended for patients undergoing endoscopy for variceal bleeding or percutaneous endoscopic gastrostomy tube placement [23] (table 3 and table 4). (See "Antibiotic prophylaxis for gastrointestinal endoscopic procedures".)

Preprocedure testing — It is generally recommended that patients not undergo routine preprocedure laboratory testing, chest radiography, or electrocardiography [24]. Instead, preprocedure testing should be used selectively based on the patient's medical history, physical examination findings, and procedural risk factors.

We agree with 2014 guidelines from the American Society for Gastrointestinal Endoscopy that recommend preprocedure testing in the following settings [24]:

●Pregnancy testing for women of childbearing potential who provide an uncertain pregnancy history or who have a history suggestive of a current pregnancy (particularly if fluoroscopy is going to be used).

●Coagulation studies for patients with active bleeding, a known or suspected bleeding disorder (including a history of abnormal bleeding), an increased risk of bleeding due to medication use (eg, ongoing anticoagulant use, prolonged antibiotic use), prolonged biliary obstruction, malnutrition, or other conditions associated with acquired coagulopathies.

●Chest radiograph for patients with new respiratory symptoms or decompensated heart failure.

●Hemoglobin/hematocrit for patients with preexisting significant anemia or active bleeding, or if there is a high risk of significant blood loss during the procedure.

●Blood typing for patients with active bleeding or anemia who are likely to need a blood transfusion.

●Serum chemistry testing for patients with significant endocrine, renal, or hepatic dysfunction if medications are to be used that may further impair function.

We do not routinely check coagulation studies for patients who are receiving anticoagulants if the medication has been held for an appropriate amount of time prior to the procedure. (See "Management of anticoagulants in patients undergoing endoscopic procedures", section on 'High or uncertain risk procedures'.)

SEDATION ASSESSMENT — An assessment of the patient's sedation needs and risks prior to the examination should be done [25-27]. This includes taking a complete history of factors that might make sedation more difficult, such as prior difficulties with sedation, narcotic or benzodiazepine use, diminished mental capacity, and agitation or severe anxiety. It also includes considering whether the patient has any characteristics that pose an increased risk for aspiration (eg, ascites, non-empty stomach, active bleeding), difficult airway management (eg, obesity, non-visibility of the uvula, prior history of difficult intubation), or increased cardiopulmonary complications of endoscopy (eg, comorbidities, obesity, older age, etc). (See "Gastrointestinal endoscopy in adults: Procedural sedation administered by endoscopists".)

INFORMED CONSENT — Informed consent is a process, not merely a form, and it is based upon all of the interactions between the healthcare provider and the patient. Informed consent includes a clear and complete explanation of all portions of the procedure. (See "Informed procedural consent".)

Five essential elements to discuss in preparation for upper endoscopy include [28,29]:

●Nature of the procedure

●Benefits

●Risks

●Alternatives

●Limitations of procedure

The use of clear and simple language is critical during the process of obtaining consent. For example, upper endoscopy might be explained as "a procedure in which a doctor passes a flexible tube with a light and a camera though your mouth and then swallowing tube (esophagus) into your stomach and the upper part of your small intestine." A discussion of the possible risks of upper endoscopy, including bleeding, perforation, and missed lesions must occur, while at the same time placing the risks and benefits of the proposed procedure in balance and in a framework the patient can understand. (See 'Complications' below.)

Written documentation of the discussion of consent is mandatory. In addition, when needed, the use of translators and materials written in a language in which the patient is fluent are also important.

TECHNIQUE — Routine upper endoscopy is performed using a high-definition white light endoscope. In addition, multiple options are available to enhance visualization during endoscopy, though many require specialized equipment and training. (See "Magnification endoscopy" and "Chromoendoscopy" and "Confocal laser endomicroscopy and endocytoscopy" and "Barrett's esophagus: Evaluation with optical chromoscopy" and "Barrett's esophagus: Evaluation with autofluorescence endoscopy".)

Routine upper gastrointestinal (GI) endoscopy may be broken down into its component parts:

●Oral intubation with the endoscope

●Oropharyngeal examination

●Esophageal examination

●Examination of the esophagogastric junction (EGJ, also referred to as the gastroesophageal junction)

●Gastric examination, including retroflexion

●Traversing the pylorus

●Duodenal examination

●Tissue sampling

●Therapeutic maneuvers

Intubation with the endoscope — Many centers begin the procedure by applying topical pharyngeal anesthesia with an agent such as a benzocaine spray. Others omit this step since it may not improve patient tolerance of the procedure and since it is associated with methemoglobinemia [30]. Finally, some endoscopists apply a small amount of benzocaine gel for topical pharyngeal anesthesia. (See 'Methemoglobinemia' below.)

For upper GI endoscopy, patients are typically placed on their left side with their neck flexed forward. A simulation of the maneuver that will be necessary to pass the endoscope from the mouth to the upper esophageal sphincter is recommended to assure proper orientation of all equipment. The upper endoscope is introduced into the mouth under direct visualization, allowing for limited visualization of the tongue, other structures in the mouth, and ultimately the hypopharynx. The endoscopist can often view the epiglottis, the vocal cords, both piriform sinuses, and the arytenoid cartilages (picture 1). In patients at risk for squamous neoplasia, particular attention should be given to both raised lesions and flat areas of discoloration with sharp borders in the oropharynx, as well as during inspection of the squamous esophagus below [31].

On the monitor, the cricopharyngeus muscle and esophageal orifice appear below the opening to the trachea, seemingly between the piriform sinuses. The endoscope is passed posteriorly toward the upper esophageal sphincter, which is at the level of the thyroid cartilage, 15 to 18 cm from the incisors. The upper esophageal sphincter is passed under direct visualization, often with the assistance of air insufflation, a gentle chin lift, and slight application of pressure.

Esophageal intubation should be done slowly and gently, in part to avoid intubation of a Zenker's diverticulum since doing so can lead to a perforation. A Zenker's diverticulum is an outpouching of the posterior oropharynx just proximal to the upper esophageal sphincter caused by decreased compliance of the upper esophageal sphincter. Care must also be taken in patients with known or suspected proximal esophageal strictures, which can make esophageal intubation difficult and can increase the risk of perforation. (See "Zenker's diverticulum".)

Esophagus and esophagogastric junction — Following intubation of the esophagus, the tubular esophagus is examined. The esophagus is typically approximately 25 cm in length. The examination should be carried out slowly and with adequate air insufflation to ensure complete visualization. Elements to note include the color of the mucosa and evidence of erythema, erosions, ulcers, strictures, rings, webs, varices, or diverticula.

The esophagogastric junction is generally approximately 40 cm from the incisors. There are both anatomic and histologic markers that separate the esophagus from the stomach. However, landmarks differentiating the esophagus from the stomach may be difficult to identify due to movement of the esophagus and stomach during the examination. The top of the gastric folds is the landmark generally believed to represent the esophagogastric junction. In patients without Barrett's esophagus, this is also the area of the squamocolumnar junction. The squamocolumnar junction is the area where the squamous epithelial lining of the esophagus meets the columnar lining of the stomach. Because this transition from squamous to columnar epithelium is typically uneven around the circumference of the lumen, it is also referred to as the Z-line. The transition from squamous to columnar epithelium results in a color change. The columnar mucosa of the stomach is salmon-colored, whereas the squamous mucosa is pale pink (picture 2). In patients without a hiatus hernia, the esophagogastric junction also corresponds with the lower esophageal sphincter, though the lower esophageal sphincter cannot be seen endoscopically. (See "Hiatus hernia", section on 'Anatomy and physiology of the gastroesophageal junction'.)

Hiatus hernias are frequently identified during upper endoscopy. A hiatus hernia is a condition where some portion of the stomach has herniated through the esophageal hiatus in the crural diaphragm. In this situation, the columnar-lined mucosa and top of the gastric folds will be seen proximal to the extrinsic narrowing of the lumen caused by the diaphragmatic pinch. Hiatus hernias may be seen during retroflexed exanimation of the stomach as well. (See "Hiatus hernia", section on 'Classification'.)

Stomach — The stomach is entered after passing the region of the esophagogastric junction. Initial visualization is usually of the relatively large folds of the greater curvature of the stomach (picture 3). The examination usually proceeds along the greater curvature of the stomach towards the pylorus (figure 1).

Certain techniques improve examination of the stomach. First, it is important to avoid full insufflation of the stomach initially, as it may induce retching or belching. Second, suctioning the pool of fluid that is often seen in the fundus upon entering the stomach improves visualization of the area. This also minimizes the risk of reflux of gastric fluid and possible aspiration. A plastic trap can be placed in line with the suction tubing to collect this fluid for pH analysis if needed. However, care should be taken to avoid applying suction to the mucosa, as doing so may create suction artifacts that appear as abnormal mucosa. In addition, since any contact between the endoscope and the mucosa can result in trauma, it is best to examine the mucosa throughout the upper GI tract while avoiding contact with the mucosa.

While all areas of the stomach should be carefully examined, particular attention should be paid to the area of the angularis along the lesser curvature, as it is often a site of pathology.

Adequate visualization of the proximal stomach and esophagogastric junction is achieved through retroflexion. Retroflexion allows the endoscopist to see areas that are not well visualized during the initial direct examination (figure 2). The technique involves the following:

●Distending the stomach with air

●Advancing the endoscope to the region of the angularis on the lesser curvature in the antrum

●Turning the endoscope up-down dial to the maximal up position to achieve a 140 to 160 degree bend at the tip of the endoscope

●Many recommend locking the wheels of the endoscope to increase stiffness of the tip of the endoscope

●Withdrawing the endoscope in order to pull the tip of the endoscope toward the esophagogastric junction (picture 4)

●Rotating the endoscope to obtain a 360 degree view of the upper stomach

Hiatus hernias are particularly easy to see when the endoscope is in the retroflexed position (picture 5). It is important to note that items placed through the endoscope's accessory channel, such as a biopsy forceps, may be difficult to use when the endoscope is in the retroflexed position. In addition, care is required to ensure that the retroflexed endoscope does not become entrapped within a hiatus hernia or in the esophagus. This is normally done by making sure that the retroflexed endoscope is not pulled into the hernia or the esophagus.

Pyloric intubation — Next, the pylorus is traversed under direct visualization (picture 6). Opening the pylorus for passage of the endoscope sometimes requires air insufflation, and patience may be required in patients who have particularly active or motile pyloric regions. Some patients have "J-shaped" stomachs, and this may increase the difficulty of intubating the pylorus due to the extreme angulation of the endoscope that may be required. Attempts to traverse the pylorus in such patients may sometimes result in significant looping in which the shaft of the endoscope presses on the greater curvature of the stomach. The pressure applied to the gastric wall by the loop can result in patient discomfort. Removing air from the stomach or application of external pressure on the abdominal wall in the left upper quadrant may help with passage in such cases.

Duodenum — After passing through the pylorus, the endoscope enters the duodenal bulb. The endoscope is then advanced through the duodenal sweep and into the second portion of the duodenum. The duodenal bulb is often devoid of characteristic features, though there may be raised bumps and polypoid areas representing either prominent Brunner's glands or heterotopic foci of gastric mucosa. The duodenum distal to the bulb has distinctive circular rings called valvulae conniventes (picture 7).

The ampulla of Vater is found in the second portion of the duodenum and is the site where the common bile duct and pancreatic duct empty into the duodenum. While the ampulla may be seen with a standard forward-viewing endoscope, a more complete examination of the ampulla requires the use of a side-viewing duodenoscope (the same endoscope used for endoscopic retrograde cholangiopancreatography). This is not done routinely as part of an upper endoscopy and requires specialized skills and equipment. However, it may be required for some patients such as those with familial adenomatous polyposis who are undergoing screening for ampullary adenomas. If examination of the ampulla is required, the examination should be performed with an endoscopist who is trained in the use of a side-viewing duodenoscope. In addition, the need for ampullary visualization should be communicated to the endoscopist prior to the procedure to ensure that the appropriate equipment is available.

DIAGNOSTIC AND THERAPEUTIC MANEUVERS — A variety of diagnostic and therapeutic maneuvers can be carried out during upper endoscopy. The most common diagnostic maneuver is tissue sampling. Other interventions include:

●Endoscopic hemostasis (see "Overview of the treatment of bleeding peptic ulcers", section on 'Endoscopic therapy' and "Methods to achieve hemostasis in patients with acute variceal hemorrhage", section on 'Initial management' and "Angiodysplasia of the gastrointestinal tract", section on 'Endoscopic treatment' and "Argon plasma coagulation in the management of gastrointestinal hemorrhage" and "Endoscopic clip therapy in the gastrointestinal tract: Bleeding lesions and beyond" and "Mallory-Weiss syndrome", section on 'Treatment of persistent and recurrent bleeding')

●Dilation of esophageal strictures, gastric outlet stenoses, and anastomotic strictures (see "Endoscopic interventions for nonmalignant esophageal strictures in adults" and "Gastric outlet obstruction in adults", section on 'Management' and "Gastrointestinal endoscopy in patients who have undergone bariatric surgery")

●Stent placement for benign or malignant disease (see "Endoscopic stenting for palliation of malignant esophageal obstruction" and "Endoscopic palliation of esophageal cancer" and "Enteral stents for the palliation of malignant gastroduodenal obstruction")

●Ablation of Barrett's esophagus (see "Barrett's esophagus: Treatment with radiofrequency ablation")

●Endoscopic mucosal resection of gastrointestinal tumors (see "Overview of endoscopic resection of gastrointestinal tumors")

●Percutaneous endoscopic gastrostomy tube placement (see "Gastrostomy tubes: Complications and their management")

●Foreign body removal (see "Ingested foreign bodies and food impactions in adults" and "Foreign bodies of the esophagus and gastrointestinal tract in children")

●Pneumatic dilation or botulinum toxin injection for achalasia (see "Pneumatic dilation and botulinum toxin injection for achalasia")

●Placement of a wireless video capsule (see "Wireless video capsule endoscopy", section on 'Capsule ingestion')

●Placement of esophageal acid monitoring devices (see "Clinical manifestations and diagnosis of gastroesophageal reflux in adults", section on 'Ambulatory esophageal pH monitoring')

●Endoscopic therapy for gastroesophageal reflux [4] (see "Radiofrequency treatment for gastroesophageal reflux disease")

●Endoscopic treatment of a Zenker's diverticulum (see "Zenker's diverticulum", section on 'Flexible endoscopy')

Tissue sampling — Tissue sampling is an important part of many upper endoscopic procedures [32,33]. This is highlighted by the fact that training guidelines emphasize the requirement that anyone performing diagnostic upper endoscopy masters standard techniques of tissue sampling, which include biopsies, brushings of the mucosal surface, and polypectomy. Specimens obtained during procedures can be sent for histologic, cytologic, or microbiologic analysis, depending on the type of sample and clinical scenario.

While making the visual assessment and deciding what sampling to perform, endoscopists should always keep in mind the clinical questions which prompted the procedure in the first place.

When submitting samples, it is helpful to provide the pathologist, cytologist, or microbiologist with details such as the clinical history, specimen-specific location and appearance, and the question to be answered. Including the endoscopy report and photographs of the area in question can also be very helpful.

The techniques of tissue sampling are usually straightforward:

●Biopsy: A biopsy forceps is placed though the accessory channel of the endoscope, advanced to the target area, and the forceps is opened and closed to obtain a pinch biopsy. Many forceps have a "spike" that allows for the acquisition of more than one sample at a time.

The tubular esophagus may be difficult to biopsy because the forceps comes out of the accessory channel parallel to the wall of the esophagus. This problem can be solved by the "turn-in" technique, where the tip of the endoscope is turned to be more perpendicular to the wall of the esophagus (or anywhere in the upper gastrointestinal tract where this is an issue), allowing for a more direct angle in which to obtain a biopsy. This technique may be augmented by suctioning of the mucosa into the biopsy forceps before tissue acquisition, allowing for a larger sample to be obtained with each "bite" of the biopsy forceps.

Typically, biopsy forceps can only sample mucosal lesions. If a submucosal lesion is encountered, it may be possible to perform stacked or tunneled biopsies in which the same location is biopsied multiple times with the hope of obtaining deeper samples. This frequently is unsuccessful and increases the risk of perforation (especially in the esophagus), so it should be done with extreme caution.

When urgent diagnosis of suspected cancer is needed in a hospital setting, endoscopic forceps biopsies can be processed by frozen section or by smashing small specimens for immediate cytology preparation. This may save time and avoid repeat procedures if delayed processed biopsies are negative [34].

●Brushings: A brush within a sheath is placed though the accessory channel of the endoscope and advanced to the target area. The brush head is advanced out of the sheath, and the endoscopist gently brushes the area of interest.

●Polypectomy: Polypectomy is carried out in a manner similar to that used during colonoscopy. Small polyps may be removed using a biopsy forceps. Larger polyps can be removed using snares that are passed down the accessory channel of the endoscope. Lesions larger than approximately 2 cm may require removal using specialized techniques. (See "Overview of endoscopic resection of gastrointestinal tumors", section on 'Endoscopic resection techniques'.)

PHOTODOCUMENTATION AND REPORTING — All endoscopic procedures should include a complete report detailing the extent of the tissue examined and all normal and abnormal findings encountered. Photodocumentation greatly enhances the record and should be included when possible.

TROUBLESHOOTING COMMON PROBLEMS IN UPPER ENDOSCOPY — Some problems occur frequently during upper gastrointestinal (GI) endoscopy and may have straightforward solutions. These include:

●Excessively motility in the stomach or small bowel may make careful examination difficult. While patience may be all that is necessary to allow the bowel to "quiet" and allow the entire examination to be completed, the use of medications to slow the bowel, including glucagon (0.5 mg intravenously [IV]), is an option. This may be particularly helpful when therapeutic maneuvers are being carried out (eg, argon plasma coagulation of an angiodysplasia).

●Bubbles and excessive mucus may obscure the view of portions of the upper GI tract during endoscopy; adequate washing using an irrigating syringe or irrigating device is often sufficient. Agents that lower the surface tension of bubbles (eg, simethicone) and mucolytic agents (eg, N-acetylcysteine) may be useful.

●Residual material in the stomach needs to be cleared for adequate visualization; again, copious irrigation is often sufficient. Prokinetic agents such as erythromycin (3 mg/kg IV) or metoclopramide (10 mg IV) given 30 to 90 minutes prior to endoscopy may facilitate passage of retained debris or blood. Residual gastric contents not only impede complete visualization, but also increase the risk of the complication of aspiration. Specialized suction devices are also available to help clear the stomach. These are most often used in the setting of upper GI bleeding.

●Abnormal anatomy (eg, a J-shaped stomach in the chest) or surgically altered anatomy (eg, bariatric surgery) may make completion of upper endoscopy more difficult. Specific maneuvers, such as changing the patient's position or the application of external abdominal pressure to "splint" the stomach, may facilitate instrument passage in some situations. (See "Gastrointestinal endoscopy in patients who have undergone bariatric surgery".)

COMPLICATIONS — Complications of upper endoscopy include complications related to sedation, complications related to the endoscopy, and complications related to diagnostic and therapeutic maneuvers [35]. Data are limited regarding the overall risk of complications. In a large survey from 1974 that was based upon 200,000 upper endoscopies, the overall complication rate was 0.13 percent, and the mortality rate was 0.004 percent [36]. Subsequent studies have estimated complication rates of 0.15 percent overall [37] and 0.0002 percent for diagnostic endoscopy without therapeutic maneuvers [38].

Complications related to sedation — The most frequent and serious complications of procedural sedation are cardiopulmonary. Risk factors for the development of cardiopulmonary complications of endoscopy include advanced age, underlying comorbid illness (especially pulmonary disease), dementia, anemia, obesity, and endoscopy performed for emergent indications [26]. Adverse events resulting from oversedation include hypoxemia, hypoventilation, airway obstruction, hypotension, vasovagal episodes, arrhythmias, and aspiration. The frequency of such unplanned cardiopulmonary events has been shown to be associated with increasing American Society of Anesthesiologists scores [26].

The overall incidence of cardiopulmonary complications is low. In a prospective survey of 14,149 upper endoscopies and a retrospective study of 21,011 endoscopic procedures, the rates of early cardiopulmonary events were 2 to 5.4 per 1000 cases and mortality rates, which included cases of aspiration pneumonia, pulmonary embolism, and myocardial infarction, were 0.3 to 0.5 per 1000 cases [39,40]. (See "Adverse events related to procedural sedation for gastrointestinal endoscopy in adults".)

Methemoglobinemia — Methemoglobin is an altered state of hemoglobin in which the ferrous (Fe2+) irons of heme are oxidized to the ferric (Fe3+) state. The ferric hemes of methemoglobin are unable to bind oxygen. In addition, the oxygen affinity of any accompanying ferrous hemes in the hemoglobin tetramer is increased [41]; as a result, the oxygen dissociation curve is "left-shifted," and oxygen delivery to the tissues is impaired (figure 3).

Topical anesthetics such as benzocaine are a common cause of methemoglobinemia. Methemoglobinemia may be clinically suspected in this setting by the presence of clinical "cyanosis" and a normal arterial PO2 (PaO2) obtained by arterial blood gas assessment, and/or the presence of "chocolate-brown blood" [42]. (See "Methemoglobinemia".)

Bleeding — Bleeding rarely occurs following diagnostic upper endoscopy. While the risk may be increased in patients with thrombocytopenia or coagulopathies, diagnostic upper endoscopy is generally thought to be safe in patients with platelet counts as low as 20,000 [36]. The risk of bleeding is increased with therapeutic maneuvers such as esophageal dilation, percutaneous endoscopic gastrostomy tube placement, or endoscopic mucosal resection. (See "Complications of endoscopic esophageal stricture dilation", section on 'Hemorrhage' and "Overview of endoscopic resection of gastrointestinal tumors", section on 'Adverse events' and "Gastrostomy tubes: Complications and their management", section on 'Bleeding' and "Gastrointestinal endoscopy in patients with disorders of hemostasis".)

Perforation — Upper endoscopy is the most common cause of esophageal perforation. It is more common when therapeutic maneuvers are carried out and in patients with esophageal diverticula. The estimated risk of esophageal perforation varies with the procedure being performed [43]:

●Diagnostic endoscopy with a flexible endoscope: 0.03 percent

●Diagnostic endoscopy with a rigid endoscope: 0.11 percent

●Stricture dilation: 0.09 to 2.2 percent

●Sclerotherapy: less than 1 percent

●Pneumatic dilation for achalasia: 2 to 6 percent

The diagnosis and management of esophageal perforations is discussed elsewhere. (See "Complications of endoscopic esophageal stricture dilation" and "Complications of endoscopic esophageal stricture dilation", section on 'Esophageal perforation' and "Surgical management of esophageal perforation".)

Infection — The risk of infection related to gastrointestinal endoscopy is low, though there have been cases of hepatitis B, hepatitis C, and bacterial transmission related to breaches in protocols for proper endoscope disinfection, including an outbreak of carbapenem-resistant Enterobacteriaceae associated with improper processing of side-viewing duodenoscopes [44]. (See "Preventing infection transmitted by gastrointestinal endoscopy" and 'Antibiotic prophylaxis' above and "Antibiotic prophylaxis for gastrointestinal endoscopic procedures".)

QUALITY INDICATORS FOR EGD — A number of quality indicators for upper endoscopy have been identified, and several have been designated key quality indicators. For upper endoscopy, recommended priority indicators are the frequency with which (unless contraindicated) ulcers with active bleeding or with nonbleeding visible vessels are treated endoscopically, the frequency with which plans for assessing Helicobacter pylori infection for patients diagnosed with gastric or duodenal ulcers are documented, the frequency with which appropriate prophylactic antibiotics are given in patients with cirrhosis with acute upper GI bleeding before EGD, and the frequency with which a proton pump inhibitor is used for suspected peptic ulcer bleeding [45].

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (see "Patient education: Upper endoscopy (The Basics)")

●Beyond the Basics topics (see "Patient education: Upper endoscopy (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●Upper endoscopy (esophagogastroduodenoscopy) includes visualization of the oropharynx, esophagus, stomach, and proximal duodenum, with real-time assessment and interpretation of the findings encountered. (See 'Introduction' above.)

●Upper gastrointestinal (GI) endoscopy is indicated in the diagnostic evaluation of signs and symptoms of a wide variety of GI disorders, as well as for therapeutic interventions (table 1). (See 'Indications' above.)

●Prior to elective upper GI endoscopy, patients typically take nothing by mouth for four to eight hours and sometimes longer if there is known or suspected delayed gastric emptying. Most medications can be continued up to the time of endoscopy and are usually taken with a small sip of water. Whether to stop antiplatelet agents or anticoagulants must take into account the procedure-related risk of bleeding and the risk of periprocedural thrombosis. Antibiotic prophylaxis is not required for the majority of patients undergoing upper endoscopy (table 3 and table 4). (See 'Patient preparation' above.)

●Routine upper endoscopy is performed using a high-definition white light endoscope. In addition, multiple options are available to enhance visualization during endoscopy, though many require specialized equipment and training. (See 'Technique' above.)

●A variety of diagnostic and therapeutic maneuvers can be carried out during upper endoscopy. The most common diagnostic maneuver is tissue sampling. (See 'Diagnostic and therapeutic maneuvers' above.)

Other interventions include:

•Endoscopic hemostasis

•Dilation of esophageal strictures, gastric outlet stenoses, anastomotic strictures

•Stent placement for benign or malignant disease

•Ablation of Barrett's esophagus

•Endoscopic mucosal resection of GI tumors

•Percutaneous endoscopic gastrostomy tube placement

•Foreign body removal

•Pneumatic dilation or botulinum toxin injection for achalasia

•Placement of a wireless video capsule

•Placement of esophageal acid monitoring devices

•Endoscopic therapy for gastroesophageal reflux

●Complications of upper endoscopy include complications due to sedation, bleeding, and perforation. (See 'Complications' above.)