Chapter 315: Gastrointestinal Endoscopy

Gastrointestinal endoscopy has been attempted for over 200 years, but the introduction of semirigid gastroscopes in the middle of the twentieth century marked the dawn of the modern endoscopic era. Since then rapid advances in endoscopic technology have led to dramatic changes in the diagnosis and treatment of many digestive diseases. Innovative endoscopic devices and new endoscopic treatment modalities continue to expand the use of endoscopy in patient care.

Flexible endoscopes provide an electronic video image generated by a charge-coupled device in the tip of the endoscope. Operator controls permit deflection of the endoscope tip; fiberoptic bundles or light-emitting diodes provide light at the tip of the endoscope; and working channels allow washing, suctioning, and the passage of instruments (Fig. 315-1). Progressive changes in the diameter and stiffness of endoscopes have improved the ease and patient tolerance of endoscopy.

UPPER ENDOSCOPY

Upper endoscopy, also referred to as esophagogastroduodenoscopy (EGD), is performed by passing a flexible endoscope through the mouth into the esophagus, stomach, and duodenum. The procedure is the best method for examining the upper gastrointestinal mucosa (Fig. 315-2). While the upper gastrointestinal radiographic series has similar accuracy for diagnosis of duodenal ulcer (Fig. 315-3), EGD is superior for detection of gastric ulcers (Fig. 315-4) and flat mucosal lesions, such as Barrett’s esophagus (Fig. 315-5), and it permits directed biopsy and endoscopic therapy. Intravenous conscious sedation is given to most patients in the United States to ease the anxiety and discomfort of the procedure, although in many countries EGD is routinely performed with topical pharyngeal anesthesia only. Patient tolerance of unsedated EGD is improved by the use of an ultrathin, 5-mm diameter endoscope that can be passed transorally or transnasally.

COLONOSCOPY

Colonoscopy is performed by passing a flexible colonoscope through the anal canal into the rectum and colon. The cecum is reached in >95% of cases and the terminal ileum (Fig. 315-6) can often be examined. Colonoscopy is the gold standard for imaging the colonic mucosa (Fig. 315-7). Colonoscopy has greater sensitivity than barium enema for colitis (Fig. 315-8), polyps (Fig. 315-9), and cancer (Fig. 315-10). CT colonography rivals the accuracy of colonoscopy for detection of some polyps and cancer, although it is not as sensitive for the detection of flat lesions, such as serrated polyps (Fig. 315-11). Conscious sedation is usually given before colonoscopy in the United States, although a willing patient and a skilled examiner can complete the procedure without sedation in many cases.

FLEXIBLE SIGMOIDOSCOPY

Flexible sigmoidoscopy is similar to colonoscopy, but it visualizes only the rectum and a variable portion of the left colon, typically to 60 cm from the anal verge. This procedure causes abdominal cramping, but it is brief and is usually performed without sedation. Flexible sigmoidoscopy is primarily used for evaluation of diarrhea and rectal outlet bleeding.

SMALL BOWEL ENDOSCOPY

Three endoscopic techniques are currently used to evaluate the small intestine, most often in patients presenting with presumed small bowel bleeding. For capsule endoscopy, the patient swallows a disposable capsule that contains a complementary metal oxide silicon (CMOS) chip camera. Color still images (Fig. 315-12) are transmitted wirelessly to an external receiver at several frames per second until the capsule’s battery is exhausted or it is passed into the toilet. Capsule endoscopy enables visualization of the small bowel mucosa beyond the reach of a conventional endoscope, and at present it is solely a diagnostic procedure. Patients with a history of prior intestinal surgery or Crohn’s disease are at risk for capsule retention at the site of a clinically unsuspected small bowel stricture, and ingestion of a “patency capsule” composed of radiologically opaque biodegradable material may be indicated prior to capsule endoscopy in such patients.

Push enteroscopy is performed with a long endoscope similar in design to an upper endoscope. The enteroscope is pushed down the small bowel, sometimes with the help of a stiffening overtube that extends from the mouth to the small intestine. The proximal to mid-jejunum is usually reached, and the instrument channel of the endoscope allows for biopsy or endoscopic therapy.

Deeper insertion into the small bowel can be accomplished by device-assisted enteroscopy, which may utilize inflatable balloons at the tip of the enteroscope and/or an overtube (single- or double-balloon enteroscopy) or a rotating, screw-like overtube (spiral enteroscopy) to pleat the small intestine onto the endoscope (Fig. 315-13, Video V5-1). Using device-assisted enteroscopy the entire small intestine can be visualized in some patients when both the oral and anal routes of insertion are used. Biopsies and endoscopic therapy can be performed throughout the visualized small bowel (Fig. 315-14).

ENDOSCOPIC RETROGRADE CHOLANGIOPANCREATOGRAPHY (ERCP)

During ERCP a side-viewing endoscope is passed through the mouth to the duodenum, the ampulla of Vater is identified and cannulated with a thin plastic catheter, and radiographic contrast material is injected into the bile duct and pancreatic duct under fluoroscopic guidance (Fig. 315-15). When indicated, the major papilla can be opened using the technique of endoscopic sphincterotomy (Fig. 315-16). Stones can be retrieved from the ducts, biopsies can be performed, and strictures can be dilated and/or stented (Fig. 315-17), and ductal leaks can be treated (Fig. 315-18). ERCP is usually performed for therapy but is also important diagnostically, and facilitates tissue sampling of biliary or pancreatic ductal strictures.

ENDOSCOPIC ULTRASOUND (EUS)

EUS utilizes ultrasound transducers incorporated into the tip of a flexible endoscope. Ultrasound images are obtained of the gut wall and adjacent organs, vessels, lymph nodes, and other structures. High-resolution images are obtained by bringing a high-frequency ultrasound transducer close to the area of interest via endoscopy. EUS provides the most accurate preoperative local staging of esophageal, pancreatic, and rectal malignancies (Fig. 315-19), but it does not detect most distant metastases. EUS is also useful for diagnosis of bile duct stones, gallbladder disease, subepithelial gastrointestinal lesions, and chronic pancreatitis. Fine-needle aspirates and core biopsies of organs, masses and lymph nodes in the posterior mediastinum, abdomen, pancreas, retroperitoneum, and pelvis can be obtained under EUS guidance (Fig. 315-20). EUS-guided therapeutic procedures are increasingly performed, including drainage of abscesses, pseudocysts, and pancreatic necrosis into the gut lumen (Video V5-2), celiac plexus neurolysis for treatment of pancreatic pain, ethanol ablation of pancreatic neuroendocrine tumors, treatment of gastrointestinal hemorrhage, and drainage of obstructed biliary and pancreatic ducts.

NATURAL ORIFICE TRANSLUMINAL ENDOSCOPIC SURGERY (NOTES)

NOTES is an evolving collection of endoscopic methods that entail passage of an endoscope or its accessories into or through the wall of the gastrointestinal tract to perform diagnostic or therapeutic interventions. Some NOTES procedures, such as percutaneous endoscopic gastrostomy (PEG) or endoscopic necrosectomy of pancreatic necrosis, are well-established clinical procedures (Video V5-2); others such as peroral endoscopic myotomy (POEM) for achalasia (Fig. 315-21), peroral endoscopic tumorectomy (POET) (Fig. 315-22), and endoscopic full-thickness resection (EFTR) of gastrointestinal mural lesions (Fig. 315-23, Video V5-3), are emerging as minimally invasive therapeutic options. NOTES is an area of continuing innovation and endoscopic research.

ENDOSCOPIC RESECTION AND CLOSURE TECHNIQUES

Endoscopic mucosal resection (EMR) (Video V5-4) and endoscopic submucosal dissection (ESD) (Fig. 315-24, Video V5-5) are the two commonly used techniques for the resection of benign and early-stage malignant gastrointestinal neoplasms. In addition to providing larger specimens for more accurate histopathological assessment and diagnosis, these techniques can be potentially curative for certain dysplastic lesions and focal intramucosal carcinomas involving the esophagus, stomach, and colon. Several devices are available for closure of EMR and ESD defects as well as gastrointestinal fistulas and perforations. Endoscopic clips deployed through the working channel of an endoscope have been used for many years to treat bleeding lesions, and the development of larger over-the-scope clips has facilitated endoscopic closure of gastrointestinal fistulas and perforations not previously amenable to endoscopic therapy (Video V5-6). Endoscopic suturing can be used to close perforations and large defects (Fig. 315-25), anastomotic leaks, and fistulas. Other potential indications for endoscopic suturing include stent fixation to prevent migration (Fig. 315-26, Video V5-7) and endoscopic bariatric procedures. These technologies are likely to have an expanding role in patient care.

Medications used during conscious sedation may cause respiratory depression or allergic reactions. All endoscopic procedures carry some risk of bleeding and gastrointestinal perforation. The risk is small with diagnostic upper endoscopy, flexible sigmoidoscopy, and colonoscopy (<1:1000 procedures), but it ranges from 0.5 to 5% when therapeutic procedures such as polypectomy, EMR, ESD, control of hemorrhage, or stricture dilation are performed. The risk of adverse events for diagnostic EUS (without needle aspiration) is similar to that for diagnostic upper endoscopy.

Infectious complications are uncommon with most endoscopic procedures. Some procedures carry a higher incidence of postprocedure bacteremia, and prophylactic antibiotics may be indicated (Table 315-1). Management of antithrombotic agents prior to endoscopic procedures should take into account the procedural risk of hemorrhage, the agent, and the patient condition, as summarized in Table 315-2.

ERCP carries additional risks. Pancreatitis occurs in ~5% of patients undergoing the procedure and in up to 30% of patients with sphincter of Oddi dysfunction. Young anicteric patients with normal ducts are at increased risk. Post-ERCP pancreatitis is usually mild and self-limited, but it may result in prolonged hospitalization, surgery, diabetes, or death when severe. Significant bleeding occurs after endoscopic sphincterotomy in ~1% of cases. Ascending cholangitis, pseudocyst infection, duodenal perforation, and abscess formation may occur as a result of ERCP.

Percutaneous gastrostomy tube placement during EGD is associated with a 10–15% incidence of adverse events, most often wound infections. Fasciitis, pneumonia, bleeding (Fig. 315-27), buried bumper syndrome, and colonic injury may result from gastrostomy tube placement.

ACUTE GASTROINTESTINAL HEMORRHAGE

Endoscopy is the primary diagnostic and therapeutic technique for patients with acute gastrointestinal hemorrhage. Although gastrointestinal bleeding stops spontaneously in most cases, some patients will have persistent or recurrent hemorrhage that may be life-threatening. Clinical predictors of rebleeding help identify patients most likely to benefit from urgent endoscopy and endoscopic, angiographic, or surgical hemostasis.

Initial Evaluation

The initial evaluation of the bleeding patient focuses on the severity of hemorrhage as reflected by the presence of supine hypotension or tachycardia, postural vital sign changes, and the frequency of hematemesis or melena. Decreases in hematocrit and hemoglobin lag behind the clinical course and are not reliable gauges of the magnitude of acute bleeding. Nasogastric tube aspiration and lavage can also be used to judge the severity of bleeding, but these are no longer routinely performed for this purpose. The bedside initial evaluation, completed well before the bleeding source is confidently identified, guides immediate supportive care of the patient, triage to the ward or intensive care unit, and timing of endoscopy. The severity of the initial hemorrhage is the most important indication for urgent endoscopy, since a large initial bleed increases the likelihood of ongoing or recurrent bleeding. Patients with resting hypotension or orthostatic change in vital signs, repeated hematemesis, bloody nasogastric aspirate that does not clear with large volume lavage, or those requiring blood transfusions should be considered for urgent endoscopy. In addition, patients with cirrhosis, coagulopathy, respiratory or renal failure, and those over 70 years of age are more likely to have significant rebleeding and to benefit from prompt evaluation and treatment.

Bedside evaluation also suggests an upper or lower gastrointestinal source of bleeding in most patients. Over 90% of patients with melena are bleeding proximal to the ligament of Treitz, and ~85% of patients with hematochezia are bleeding from the colon. Melena can result from bleeding in the small bowel or right colon, especially in older patients with slow colonic transit. Conversely, some patients with massive hematochezia may be bleeding from an upper gastrointestinal source, such as a gastric Dieulafoy lesion or duodenal ulcer, with rapid intestinal transit. Early upper endoscopy should be considered in such patients.

Endoscopy should be performed after the patient has been resuscitated with intravenous fluids and transfusions, as necessary. Marked coagulopathy or thrombocytopenia is usually treated before endoscopy, since correction of these abnormalities may lead to resolution of bleeding, and techniques for endoscopic hemostasis are limited in such patients. Metabolic derangements should also be addressed. Tracheal intubation for airway protection should be considered before upper endoscopy in patients with repeated recent hematemesis, encephalopathy and suspected variceal hemorrhage. A single dose of erythromycin (3–4 mg/kg or 250 mg) administered intravenously 30–90 min prior to upper endoscopy increases gastric emptying and may clear blood and clots from the stomach to improve endoscopic visualization.

Most patients with hematochezia who are otherwise stable can undergo semielective colonoscopy. Controlled trials have not shown a benefit to urgent colonoscopy in patients hospitalized with hematochezia, although patients with massive or recurrent large-volume episodes of hematochezia should undergo urgent colonoscopy after a rapid colonic purge with a polyethylene glycol solution. Colonoscopy has a higher diagnostic yield than radionuclide bleeding scans or angiography in lower gastrointestinal bleeding, and endoscopic therapy can be applied in some cases. Urgent colonoscopy can be hindered by poor visualization due to persistent vigorous bleeding with recurrent hemodynamic instability, and other techniques (such as angiography or even emergent subtotal colectomy) must be employed. In such patients, massive bleeding originating from an upper gastrointestinal source should also be considered and excluded promptly by upper endoscopy. The anal and rectal mucosa should also be visualized endoscopically early in the course of massive rectal bleeding, as bleeding lesions in or close to the anal canal may be identified that are amenable to endoscopic or surgical transanal hemostatic techniques.

Peptic Ulcer

The endoscopic appearance of peptic ulcers provides useful prognostic information and guides the need for endoscopic therapy in patients with acute hemorrhage (Fig. 315-28). A clean-based ulcer is associated with a low risk (3–5%) of rebleeding; patients with melena and a clean-based ulcer are often discharged home from the emergency room or endoscopy suite if they are young, reliable, and otherwise healthy. Flat pigmented spots and adherent clots covering the ulcer base have a 10% and 20% risk of rebleeding, respectively. Endoscopic therapy may be considered for an ulcer with an adherent clot. When a fibrin plug is seen protruding from a vessel wall in the base of an ulcer (so-called sentinel clot or visible vessel), the risk of rebleeding from the ulcer is 40%. This finding generally leads to endoscopic therapy to decrease the rebleeding rate. When active spurting from an ulcer is seen, there is a 90% risk of ongoing bleeding without therapy.

Endoscopic therapy of ulcers with high-risk stigmata typically lowers the rebleeding rate to 5–10%. Several hemostatic techniques are available, including injection of epinephrine or a sclerosant into and around the vessel (Fig. 315-29), “coaptive coagulation” of the vessel in the base of the ulcer using a thermal probe that is pressed against the site of bleeding (Fig. 315-30), placement of through-the-scope hemoclips (Fig. 315-31) or an over-the-scope clip (Fig. 315-32), or a combination of these modalities (Video V5-8). In conjunction with endoscopic therapy, the administration of a proton pump inhibitor decreases the risk of rebleeding and improves patient outcome.

Varices

Two complementary strategies guide therapy of bleeding varices: local treatment of the bleeding varices and treatment of the underlying portal hypertension. Local therapies, including endoscopic variceal band ligation, endoscopic variceal sclerotherapy (EVS), stent placement and balloon tamponade with a Sengstaken-Blakemore tube, effectively control acute hemorrhage in most patients, although therapies that decrease portal pressure (pharmacologic treatment, surgical shunts, or radiologically placed intrahepatic portosystemic shunts) also play an important role.

Endoscopic variceal ligation (EVL) is indicated for the prevention of a first bleed (primary prophylaxis) from large esophageal varices (Fig. 315-33), particularly in patients in whom nonselective beta blockers are contraindicated or not tolerated. EVL is also the preferred endoscopic therapy for control of active esophageal variceal bleeding and for subsequent eradication of esophageal varices (secondary prophylaxis). During EVL a varix is suctioned into a cap fitted on the end of the endoscope, and a rubber band is released from the cap, ligating the varix (Fig. 315-34, Video V5-9). EVL controls acute hemorrhage in up to 90% of patients. Complications of EVL, such as postligation ulcer bleeding and esophageal stenosis, are uncommon. EVS involves the injection of a sclerosing, thrombogenic solution into or next to esophageal varices. EVS also controls acute hemorrhage in most patients, but it is generally used as salvage therapy when band ligation fails because of its higher complication rate. Bleeding from large gastric fundic varices (Fig. 315-35) is best treated with endoscopic cyanoacrylate (“glue”) injection (Video V5-10), since EVL or EVS of these varices is associated with a high rebleeding rate. Complications of cyanoacrylate injection include infection and glue embolization to other organs, such as the lungs, brain, and spleen.

After treatment of the acute hemorrhage, an elective course of endoscopic therapy can be undertaken with the goal of eradicating esophageal varices and preventing rebleeding months to years later. However, this chronic therapy is less successful, preventing long-term rebleeding in ~50% of patients. Pharmacologic therapies that decrease portal pressure have similar efficacy, and the two modalities are usually combined.

Dieulafoy’s Lesion

This lesion, also called persistent caliber artery, is a large-caliber arteriole that runs immediately beneath the gastrointestinal mucosa and bleeds through a focal mucosal erosion (Fig. 315-36). Dieulafoy’s lesion is seen most commonly on the lesser curvature of the proximal stomach, causes impressive arterial hemorrhage, and may be difficult to diagnose when not actively bleeding; it is often recognized only after repeated endoscopy for recurrent bleeding. Endoscopic therapy, such as thermal coagulation, band ligation, or endoscopic suturing, is typically effective for control of bleeding and sealing of the underlying vessel once the lesion has been identified (Video V5-11). Rescue therapies, such as angiographic embolization or surgical oversewing, are considered in situations where endoscopic therapy has failed.

Mallory-Weiss Tear

A Mallory-Weiss tear is a linear mucosal rent near or across the gastroesophageal junction that is often associated with retching or vomiting (Fig. 315-37). When the tear disrupts a submucosal arteriole, brisk hemorrhage may result. Endoscopy is the best method for diagnosis, and an actively bleeding tear can be treated endoscopically with epinephrine injection, coaptive coagulation, band ligation, or hemoclips (Video V5-12). Unlike peptic ulcer, a Mallory-Weiss tear with a nonbleeding sentinel clot in its base rarely rebleeds and thus does not necessitate endoscopic therapy.

Vascular Ectasias

Vascular ectasias are flat mucosal vascular anomalies that are best diagnosed by endoscopy. They usually cause slow intestinal blood loss and occur either in a sporadic fashion or in a well-defined pattern of distribution (e.g., gastric antral vascular ectasia [GAVE] or “watermelon stomach”) (Fig. 315-38). Cecal vascular ectasias, GAVE, and radiation-induced rectal ectasias are often responsive to local endoscopic ablative therapy, such as argon plasma coagulation (Video V5-13). Patients with diffuse small bowel vascular ectasias (associated with chronic renal failure and with hereditary hemorrhagic telangiectasia) may continue to bleed despite endoscopic treatment of easily accessible lesions by conventional endoscopy. These patients may benefit from device-assisted enteroscopy with endoscopic therapy or pharmacologic treatment with octreotide or estrogen/progesterone.

Colonic Diverticula

Diverticula form where nutrient arteries penetrate the muscular wall of the colon en route to the colonic mucosa (Fig. 315-39). The artery found in the base of a diverticulum may bleed, causing painless and impressive hematochezia. Colonoscopy is indicated in patients with hematochezia and suspected diverticular hemorrhage, since other causes of bleeding (such as vascular ectasias, colitis, and colon cancer) must be excluded. In addition an actively bleeding diverticulum may be seen and treated during colonoscopy (Fig. 315-40, Video V5-14).

GASTROINTESTINAL OBSTRUCTION AND PSEUDOOBSTRUCTION

Endoscopy is useful for evaluation and treatment of some forms of gastrointestinal obstruction. An important exception is small-bowel obstruction due to surgical adhesions, which is generally not diagnosed or treated endoscopically. Esophageal, gastroduodenal, and colonic obstruction or pseudoobstruction can all be diagnosed and often managed endoscopically.

Acute Esophageal Obstruction

Esophageal obstruction by impacted food (Fig. 315-41) or an ingested foreign body (Fig. 315-42) is a potentially life-threatening event and represents an endoscopic emergency. Left untreated, the patient may develop esophageal ulceration, ischemia, and perforation. Patients with persistent esophageal obstruction often have hypersalivation and are usually unable to swallow water. Sips of a carbonated beverage, sublingual nifedipine or nitrates, or intravenous glucagon may resolve an esophageal food impaction, but in most patients an underlying web, ring, or stricture is present and endoscopic removal of the obstructing food bolus is necessary. Endoscopy is generally the best initial test in such patients since endoscopic removal of the obstructing material is usually possible, and the presence of an underlying esophageal pathology can often be determined. Radiographs of the chest and neck should be considered before endoscopy in patients with fever, obstruction for ≥24 h, or ingestion of a sharp object, such as a fishbone. Radiographic contrast studies interfere with subsequent endoscopy and are not advisable in most patients with a clinical picture of esophageal obstruction.

Gastric Outlet Obstruction

Obstruction of the gastric outlet is commonly caused by gastric, duodenal, or pancreatic malignancy, or chronic peptic ulceration with stenosis of the pylorus (Fig. 315-43). Patients vomit partially digested food many hours after eating. Gastric decompression with a nasogastric tube and subsequent lavage for removal of retained material is the first step in treatment. The diagnosis can then be confirmed with a saline load test, if desired. Endoscopy is useful for diagnosis and treatment. Patients with benign pyloric stenosis may be treated with endoscopic balloon dilation of the pylorus, and a course of endoscopic dilation results in long-term relief of symptoms in ~50% of patients. Removable, fully covered lumen-apposing metal stents (LAMS) may also be used to treat benign pyloric stenosis (Video V5-15). Malignant gastric outlet obstruction can be relieved with endoscopically placed expandable stents in patients with inoperable malignancy (Video V5-16).

Colonic Obstruction and Pseudoobstruction

These conditions both present with abdominal distention and discomfort, tympany, and a dilated colon on plain abdominal radiography. The radiographic appearance may be characteristic of a particular condition, such as sigmoid volvulus (Fig. 315-44). Both obstruction and pseudoobstruction may lead to colonic perforation if left untreated. Acute colonic pseudoobstruction is a form of colonic ileus that is usually attributable to electrolyte disorders, narcotic and anticholinergic medications, immobility (as after surgery), or retroperitoneal hemorrhage or mass. Multiple causative factors are often present. Colonoscopy, water-soluble contrast enema, or CT may be used to assess for an obstructing lesion and differentiate obstruction from pseudoobstruction. One of these diagnostic studies should be strongly considered if the patient does not have clear risk factors for pseudoobstruction, if radiographs do not show air in the rectum, or if the patient fails to improve when underlying causes of pseudoobstruction have been addressed. The risk of cecal perforation in pseudoobstruction rises when the cecal diameter exceeds 12 cm, and decompression of the colon may be achieved using intravenous neostigmine or via colonoscopic decompression (Fig. 315-45). Most patients should receive a trial of conservative therapy (with correction of electrolyte disorders, removal of offending medications, and increased mobilization) before undergoing an invasive decompressive procedure for colonic pseudoobstruction.

Colonic obstruction is an indication for urgent intervention. In the past, emergent diverting colostomy was usually performed with a subsequent second operation after bowel preparation to treat the underlying cause of obstruction. Colonoscopic placement of an expandable stent is an alternative treatment option that can relieve malignant colonic obstruction without emergency surgery and permit bowel preparation for an elective one-stage operation (Fig. 315-46, Video V5-17).

ACUTE BILIARY OBSTRUCTION

The steady, severe pain that occurs when a gallstone acutely obstructs the common bile duct often brings patients to a hospital. The diagnosis of a ductal stone is suspected when the patient is jaundiced or when serum liver tests or pancreatic enzyme levels are elevated; it is confirmed by EUS, magnetic resonance cholangiography (MRCP), or direct cholangiography (performed endoscopically, percutaneously, or during surgery). ERCP is the primary means of treating common bile duct stones (Figs. 315-15 and 315-16), although they can also be removed by laparoscopic bile duct exploration at the time of cholecystectomy. Radiologic percutaneous biliary drainage may be required in some cases.

Bile Duct Imaging

While transabdominal ultrasound diagnoses only a minority of bile duct stones, MRCP and EUS are >90% accurate and have an important role in diagnosis. Examples of these modalities are shown in Fig. 315-47.

If the suspicion for a bile duct stone is high and urgent treatment is required (as in a patient with obstructive jaundice and biliary sepsis), ERCP is the procedure of choice since it remains the gold standard for diagnosis and allows for immediate treatment (Video V5-18). If a persistent bile duct stone is relatively unlikely (as in a patient with gallstone pancreatitis), ERCP may be supplanted by less invasive imaging techniques, such as EUS, MRCP, or intraoperative cholangiography performed during cholecystectomy, sparing some patients the risk and discomfort of ERCP.

Ascending Cholangitis

Charcot’s triad of jaundice, abdominal pain, and fever is present in ~70% of patients with ascending cholangitis and biliary sepsis. These patients are managed initially with fluid resuscitation and intravenous antibiotics. Abdominal ultrasound is often performed to assess for gallbladder stones and bile duct dilation. However, the bile duct may not be dilated early in the course of acute biliary obstruction. Medical management usually improves the patient’s clinical status, providing a window of ~24 h during which biliary drainage should be established, typically by ERCP. Undue delay can result in recrudescence of overt sepsis and increased morbidity and mortality rates. In addition to Charcot’s triad, the additional presence of shock and confusion (Reynolds’s pentad) is associated with a high mortality rate and should prompt urgent intervention to restore biliary drainage.

Gallstone Pancreatitis

Gallstones may cause acute pancreatitis as they pass through the ampulla of Vater. The occurrence of gallstone pancreatitis usually implies passage of a stone into the duodenum, and only ~20% of patients harbor a persistent stone in the ampulla or the common bile duct. Retained stones are more common in patients with jaundice, rising serum liver tests following hospitalization, severe pancreatitis, or superimposed ascending cholangitis.

Urgent ERCP decreases the morbidity rate of gallstone pancreatitis in a subset of patients with retained bile duct stones. It is unclear whether the benefit of ERCP is mainly attributable to treatment and prevention of ascending cholangitis or to relief of pancreatic ductal obstruction. ERCP is warranted early in the course of gallstone pancreatitis if ascending cholangitis is suspected, especially in a jaundiced patient. Urgent ERCP may also benefit patients predicted to have severe pancreatitis using a clinical index of severity, such as the Glasgow or Ranson score. Since the benefit of ERCP is limited to patients with a retained bile duct stone, a strategy of initial MRCP or EUS for diagnosis decreases the utilization of ERCP in gallstone pancreatitis and improves clinical outcomes by limiting the occurrence of ERCP-related adverse events.

DYSPEPSIA

Dyspepsia is a chronic or recurrent burning discomfort or pain in the upper abdomen that may be caused by diverse processes, such as gastroesophageal reflux, peptic ulcer disease, and “nonulcer dyspepsia,” a heterogeneous category that includes disorders of motility, sensation and somatization. Gastric and esophageal malignancies are less common causes of dyspepsia. Careful history-taking allows accurate differential diagnosis of dyspepsia in only about half of patients. In the remainder, endoscopy can be a useful diagnostic tool, especially in patients whose symptoms are not resolved by Helicobacter pylori treatment or an empirical trial of acid-reducing therapy. Endoscopy should be performed at the outset in patients with dyspepsia and alarm features, such as weight loss or iron-deficiency anemia.

GASTROESOPHAGEAL REFLUX DISEASE (GERD)

When classic symptoms of gastroesophageal reflux are present, such as water brash and substernal heartburn, presumptive diagnosis and empirical treatment are often sufficient. Endoscopy is a sensitive test for diagnosis of esophagitis (Fig. 315-48), but it will miss nonerosive reflux disease (NERD) since some patients have symptomatic reflux without esophagitis. The most sensitive test for diagnosis of GERD is 24-h ambulatory pH monitoring. Endoscopy is indicated in patients with reflux symptoms refractory to antisecretory therapy; in those with alarm symptoms, such as dysphagia, weight loss, or gastrointestinal bleeding; and in those with recurrent dyspepsia after treatment that is not clearly due to reflux on clinical grounds alone. Endoscopy should be considered in patients with long-standing (≥10 years) GERD, as they have a sixfold increased risk of harboring Barrett’s esophagus compared to patients with <1 year of reflux symptoms.

Barrett’s Esophagus

Barrett’s esophagus is specialized columnar metaplasia that replaces the normal squamous mucosa of the distal esophagus in some persons with GERD. Barrett’s epithelium is a major risk factor for adenocarcinoma of the esophagus and is readily detected endoscopically, due to proximal displacement of the squamocolumnar junction (Fig. 315-5). A screening EGD for Barrett’s esophagus should be considered in patients with a chronic (≥10 year) history of GERD symptoms. Endoscopic biopsy is the gold standard for confirmation of Barrett’s esophagus and for dysplasia or cancer arising in Barrett’s mucosa.

Periodic EGD with biopsies is recommended for surveillance of patients with Barrett’s esophagus. Endoscopic resection (EMR or ESD) and/or ablation are performed when high-grade dysplasia or intramucosal cancer are found in the Barrett’s mucosa. Although guidelines recommend observation and surveillance of low-grade dysplasia in Barrett’s mucosa, recent evidence suggests that endoscopic treatment may be appropriate in select patients. Radiofrequency ablation (RFA) is the commonest ablative modality used for endoscopic treatment of Barrett’s esophagus, and other modalities, such as cryotherapy, are also available.

PEPTIC ULCER

Peptic ulcer classically causes epigastric gnawing or burning, often occurring nocturnally and promptly relieved by food or antacids. Although endoscopy is the most sensitive diagnostic test for peptic ulcer, it is not a cost-effective strategy in young patients with ulcer-like dyspeptic symptoms unless endoscopy is available at low cost. Patients with suspected peptic ulcer should be evaluated for H. pylori infection. Serology (past or present infection), urea breath testing (current infection), and stool tests are noninvasive and less costly than endoscopy with biopsy. Patients aged >50 and those with alarm symptoms or persistent symptoms despite treatment should undergo endoscopy to exclude malignancy.

NONULCER DYSPEPSIA

Nonulcer dyspepsia may be associated with bloating and, unlike peptic ulcer, tends not to remit and recur. Most patients describe persistent symptoms despite acid-reducing, prokinetic, or anti-Helicobacter therapy, and are referred for endoscopy to exclude a refractory ulcer and assess for other causes. Although endoscopy is useful for excluding other diagnoses, its impact on the treatment of patients with nonulcer dyspepsia is limited.

DYSPHAGIA

About 50% of patients presenting with difficulty swallowing have a mechanical obstruction; the remainder has a motility disorder, such as achalasia or diffuse esophageal spasm. Careful history-taking often points to a presumptive diagnosis and leads to the appropriate use of diagnostic tests. Esophageal strictures (Fig. 315-49) typically cause progressive dysphagia, first for solids, then for liquids; motility disorders often cause intermittent dysphagia for both solids and liquids. Some underlying disorders have characteristic historic features: Schatzki’s ring (Fig. 315-50) causes episodic dysphagia for solids, typically at the beginning of a meal; oropharyngeal motor disorders typically present with difficulty initiating deglutition (transfer dysphagia) and nasal reflux or coughing with swallowing; and achalasia may cause nocturnal regurgitation of undigested food.

When mechanical obstruction is suspected, endoscopy is a useful initial diagnostic test, since it permits immediate biopsy and/or dilation of strictures, masses, or rings. The presence of linear furrows and multiple corrugated rings throughout a narrowed esophagus (feline esophagus) should raise suspicion for eosinophilic esophagitis, an increasingly recognized cause for recurrent dysphagia and food impaction (Fig. 315-51). Blind or forceful passage of an endoscope may lead to perforation in a patient with stenosis of the cervical esophagus or a Zenker’s diverticulum, but gentle passage of an endoscope under direct visual guidance is reasonably safe. Endoscopy can miss a subtle stricture or ring in some patients.

When transfer dysphagia is evident or an esophageal motility disorder is suspected, esophageal radiography and/or a video-swallow study are the best initial diagnostic tests. The oropharyngeal swallowing mechanism, esophageal peristalsis, and the lower esophageal sphincter can all be assessed. In some disorders, subsequent esophageal manometry may also be important for diagnosis.

Various causes of dysphagia are amenable to endoscopic therapy. Benign strictures, rings, and webs can be dilated using a through-the-scope balloon (Fig. 315-52) or a polyvinyl dilator passed over a guide wire. In some instances, thin fibrotic strictures may respond to needle-knife electroincision (Fig. 315-53) when they prove refractory to dilation. Esophageal covered stents can be used to palliate dysphagia from malignant obstruction (Fig. 315-54), and flexible endoscopic myotomy is an option for Zenker’s diverticulum (Video V5-19). Recent advances in submucosal endoscopy have enabled the development of procedures, such as POEM (Video V5-20) and POET (Video V5-21) for the management of achalasia and select subepithelial esophageal tumors, respectively.

ENDOSCOPIC TREATMENT OF OBESITY

The majority of Americans are overweight or obese, and obesity-associated diabetes has become a major public health problem. Bariatric surgery is the most effective weight-loss intervention, and it has been shown to decrease long-term mortality in obese persons, but many patients do not undergo surgery. Endoscopic treatments for obesity have been developed and include insertion of an intragastric balloon or duodenojejunal bypass liner, placement of a percutaneous gastric tube for aspiration of gastric contents after meals, or endoscopic sleeve gastroplasty, which utilizes endoscopic suturing to narrow the lumen of the gastric body (Video V5-22). Prospective trials show that these treatments induce total body weight loss of 7–20% and varying degrees of glycemic control. Additional endoscopic modalities are undergoing initial clinical trials. The long-term efficacy of endoscopic bariatric treatment is currently unknown.

TREATMENT OF MALIGNANCIES

Endoscopy plays an important role in the treatment of gastrointestinal malignancies. Early-stage malignancies limited to the superficial layers of the gastrointestinal mucosa may be resected using the techniques of EMR (Video V5-4) or ESD (Video V5-5). Photodynamic therapy (PDT) and RFA are effective modalities for ablative treatment of high-grade dysplasia and intramucosal cancer in Barrett’s esophagus (Video V5-23). Gastrointestinal stromal tumors can be removed en bloc by EFTR (Video V5-3). In general, endoscopic techniques offer the advantage of a minimally invasive approach to treatment but rely on other imaging techniques (such as CT, MRI, positron emission tomography [PET], and EUS) to exclude distant metastases or locally advanced disease better treated by surgery or other modalities. The decision to treat an early-stage gastrointestinal malignancy endoscopically is often made in collaboration with a surgeon and/or oncologist.

Endoscopic palliation of gastrointestinal malignancies relieves symptoms and in many cases prolongs survival. Malignant obstruction can be relieved by endoscopic stent placement (Figs. 315-17, 315-54, and 315-55; Videos V5-16, V5-17), and malignant gastrointestinal bleeding can often be palliated endoscopically as well. EUS-guided celiac plexus neurolysis may relieve pancreatic cancer pain.

ANEMIA AND OCCULT BLOOD IN THE STOOL

Iron-deficiency anemia may be attributed to poor iron absorption (as in celiac sprue) or, more commonly, chronic blood loss. Intestinal bleeding should be strongly suspected in men and postmenopausal women with iron-deficiency anemia, and colonoscopy is indicated in such patients, even in the absence of detectable occult blood in the stool. Approximately 30% will have large colonic polyps, 10% will have colorectal cancer, and a few patients will have colonic vascular lesions. When a convincing source of blood loss is not found in the colon, upper gastrointestinal endoscopy should be considered; if no lesion is found, duodenal biopsies should be obtained to exclude sprue (Fig. 315-56). Small bowel evaluation with capsule endoscopy (Fig. 315-57), CT or MR enterography, or device-assisted enteroscopy may be appropriate if both EGD and colonoscopy are unrevealing.

Tests for occult blood in the stool detect hemoglobin or the heme moiety and are most sensitive for colonic blood loss, although they will also detect larger amounts of upper gastrointestinal bleeding. Patients with occult blood in normal-appearing stool should undergo colonoscopy to diagnose or exclude colorectal neoplasia, especially if they are over 50 years of age or have a family history of colonic neoplasia. Whether upper endoscopy is also indicated depends on the patient’s symptoms.

The small intestine may be the source of chronic intestinal bleeding, especially if colonoscopy and upper endoscopy are not diagnostic. The utility of small bowel evaluation varies with the clinical setting and is most important in patients in whom bleeding causes chronic or recurrent anemia. In contrast to the low diagnostic yield of small bowel radiography, positive findings on capsule endoscopy are seen in 50–70% of patients with suspected small intestinal bleeding. The most common finding is mucosal vascular ectasia. CT or MR enterography accurately detects small bowel masses and inflammation, and are also useful for initial small bowel evaluation. Deep enteroscopy may follow capsule endoscopy for biopsy of lesions or to provide specific therapy, such as argon plasma coagulation of vascular ectasias (Fig. 315-58).

COLORECTAL CANCER SCREENING

The majority of colon cancers develop from preexisting colonic adenomas, and colorectal cancer can be largely prevented by the detection and removal of adenomatous polyps (Video V5-24). The choice of screening strategy for an asymptomatic person depends on personal and family history. Individuals with inflammatory bowel disease, a history of colorectal polyps or cancer, family members with adenomatous polyps or cancer, or certain familial cancer syndromes (Fig. 315-59) are at increased risk for colorectal cancer. An individual without these factors is generally considered at average risk.

Screening strategies are summarized in Table 315-3. While stool tests for occult blood have been shown to decrease mortality rate from colorectal cancer, they do not detect some cancers and many polyps, and direct visualization of the colon is a more effective screening strategy. Either sigmoidoscopy or colonoscopy may be used for cancer screening in asymptomatic average-risk individuals. The use of sigmoidoscopy was based on the historical finding that the majority of colorectal cancers occurred in the rectum and left colon, and that patients with right-sided colon cancers had left-sided polyps. Over the past several decades, however, the distribution of colon cancers has changed in the United States, with proportionally fewer rectal and left-sided cancers than in the past. Large American studies of colonoscopy for screening of average-risk individuals show that cancers are roughly equally distributed between left and right colon and half of patients with right-sided lesions have no polyps in the left colon. Visualization of the entire colon thus appears to be the optimal strategy for colorectal cancer screening and prevention.

Virtual colonoscopy (VC) is a radiologic technique that images the colon with CT following rectal insufflation of the colonic lumen. Computer rendering of CT images generates an electronic display of a virtual “flight” along the colonic lumen, simulating colonoscopy (Fig. 315-60). Findings detected during VC often require subsequent conventional colonoscopy for confirmation and treatment.

DIARRHEA

Most cases of diarrhea are acute, self-limited, and due to infections or medication. Chronic diarrhea (lasting >6 weeks) is more often due to a primary inflammatory, malabsorptive, or motility disorder, is less likely to resolve spontaneously, and generally requires diagnostic evaluation. Patients with chronic diarrhea or severe, unexplained acute diarrhea often undergo endoscopy if stool tests for pathogens are unrevealing. The choice of endoscopic testing depends on the clinical setting.

Patients with colonic symptoms and findings such as bloody diarrhea, tenesmus, fever, or leukocytes in stool generally undergo sigmoidoscopy or colonoscopy to assess for colitis (Fig. 315-8). Sigmoidoscopy is an appropriate initial test in most patients. Conversely, patients with symptoms and findings suggesting small bowel disease, such as large-volume watery stools, substantial weight loss, and malabsorption of iron, calcium, or fat, may undergo upper endoscopy with duodenal aspirates for assessment of bacterial overgrowth and biopsies for assessment of mucosal diseases, such as celiac sprue.

Many patients with chronic diarrhea do not fit either of these patterns. In the setting of a long-standing history of alternating constipation and diarrhea dating to early adulthood, without findings such as blood in the stool or anemia, a diagnosis of irritable bowel syndrome may be made without direct visualization of the bowel. Steatorrhea and upper abdominal pain may prompt evaluation of the pancreas rather than the gut. Patients whose chronic diarrhea is not easily categorized often undergo initial colonoscopy to examine the entire colon and terminal ileum for inflammatory or neoplastic disease (Fig. 315-61).

MINOR HEMATOCHEZIA

Bright red blood passed with or on formed brown stool usually has a rectal, anal, or distal sigmoid source (Fig. 315-62). Patients with even trivial amounts of hematochezia should be investigated with flexible sigmoidoscopy and anoscopy to exclude polyps or cancers in the distal colon. Patients reporting red blood on the toilet tissue only, without blood in the toilet or on the stool, are generally bleeding from a lesion in the anal canal; careful external inspection, digital examination, and proctoscopy with anoscopy may be sufficient for diagnosis in such cases.

PANCREATITIS

About 20% of patients with pancreatitis have no identified cause after routine clinical investigation (including a review of medication and alcohol use, measurement of serum triglyceride and calcium levels, abdominal ultrasonography, and CT or MR). Endoscopic assessment leads to a specific diagnosis in the majority of such patients, often altering clinical management. Endoscopic investigation is particularly appropriate if the patient has had more than one episode of pancreatitis.

Microlithiasis, or the presence of microscopic crystals in bile, is a leading cause of previously unexplained acute pancreatitis and is sometimes seen during abdominal ultrasonography as layering sludge or flecks of floating, echogenic material in the gallbladder. EUS may identify previously undetected microlithiasis.

Previously undetected chronic pancreatitis, pancreatic malignancy, or pancreas divisum may be diagnosed by either ERCP or EUS. Autoimmune pancreatitis is often suspected on the basis of CT, MR, or serologic findings, but it may first become apparent during EUS and may require EUS-guided pancreatic biopsy for histologic diagnosis.

Severe pancreatitis often results in pancreatic fluid collections. Symptomatic pseudocysts and areas of walled-off pancreatic necrosis can be drained into the stomach or duodenum endoscopically, using transpapillary and transmural endoscopic techniques. Pancreatic necrosis can be treated by direct endoscopic necrosectomy (Video V5-2) via an endoscopically created transmural drainage site.

CANCER STAGING

Local staging of esophageal, gastric, pancreatic, bile duct, and rectal cancers can be obtained with EUS (Fig. 315-19). EUS with fine-needle aspiration (Fig. 315-20) currently provides the most accurate preoperative assessment of local tumor and nodal staging, but it does not detect many distant metastases. Details of the local tumor stage can guide treatment decisions including resectability and need for neoadjuvant therapy. EUS with transesophageal needle biopsy may also be used to assess the presence of non-small-cell lung cancer in mediastinal nodes.

Direct scheduling of endoscopic procedures by primary care physicians without preceding gastroenterology consultation, or open-access endoscopy, is common. When the indications for endoscopy are clear-cut and appropriate, the procedural risks are low, and the patient understands what to expect, open-access endoscopy streamlines patient care and decreases costs.

Patients referred for open-access endoscopy should have a recent history, physical examination, and medication review. A copy of such an evaluation should be available when the patient comes to the endoscopy suite. Patients with unstable cardiovascular or respiratory conditions should not be referred directly for open-access endoscopy. Patients with particular conditions and undergoing certain procedures should be prescribed prophylactic antibiotics prior to endoscopy (Table 315-1). In addition, patients taking anticoagulants and/or antiplatelet drugs may require adjustment of these agents before endoscopy based on the procedural risk for bleeding and their underlying risk for a thromboembolic event (Table 315-2).

Common indications for open-access EGD include dyspepsia resistant to a trial of appropriate therapy, dysphagia, gastrointestinal bleeding, and persistent anorexia or early satiety. Open-access colonoscopy is often requested in men or postmenopausal women with iron-deficiency anemia, in patients age >50 with occult blood in the stool, in patients with a previous history of colorectal adenomatous polyps or cancer, and for colorectal cancer screening. Flexible sigmoidoscopy is commonly performed as an open-access procedure.

When patients are referred for open-access colonoscopy, the primary care provider may need to choose a colonic preparation. Commonly used oral preparations include polyethylene glycol lavage solution, with or without citric acid. A “split-dose” regimen improves the quality of colonic preparation. Sodium phosphate purgatives may cause fluid and electrolyte abnormalities and renal toxicity, especially in patients with renal failure or congestive heart failure and those >70 years of age.