A recognition of the increased risk for infections associated with certain endoscopic procedures and patient risk factors allows the use of prophylactic antibiotics in select situations (Table 40-1).¹ These antibiotics are intended to prevent local complications such as cellulitis around a percutaneous endoscopic gastrostomy (PEG) tube site following its placement or infection of a pancreatic cyst following endoscopic ultrasonography (EUS)–guided fine-needle aspiration (FNA). Other infections may be the consequence of procedure-related bacteremia. Whereas patients with cardiac valve abnormalities may be at an increased risk for endocarditis from bacteremia, the role of prophylactic antibiotics for these patients has recently been reevaluated. The risk of endocarditis following endoscopy is very low and is likely less than the risk of endocarditis from ordinary daily activities such as teeth brushing. For these reasons, the American Society for Gastrointestinal Endoscopy and the American Heart Association no longer recommend routine use of prophylactic antibiotics prior to endoscopy.^1,²

Table 40-1 Endoscopic Procedures for Which Antibiotic Prophylaxis Is Recommended *

ERCP, endoscopic retrograde cholangiopancreatography; EUS-FNA, endoscopic ultrasonography–fine-needle aspiration; PEG, percutaneous endoscopic gastrostomy.

* Antibiotics are not recommended for prevention of endocarditis and in patients with vascular grafts or prosthetic joints.

† Antibiotics recommended at time of hospital admission for all cirrhotic patients with gastrointestinal bleeding.

MANAGEMENT OF ANTICOAGULANT AND ANTIPLATELET DRUGS

Patients taking warfarin are at increased risks for bleeding following polypectomy, endoscopic sphincterotomy, balloon dilation, percutaneous gastrostomy, and EUS-FNA aspiration.³ Warfarin should be held before these procedures so that the prothrombin time (or international normalized ratio, INR) can return to normal and be restarted within 1 week after the procedure. In patients with mechanical heart valves and other situations at high risk for thromboembolism, use of unfractionated or low-molecular-weight heparin should be substituted for warfarin except during the 12 hours before and after the procedure.³^–⁵

Drugs that affect platelet function such as aspirin, nonsteroidal anti-inflammatory drugs, ticlopidine, clopidogrel, and other newer agents have not been clearly shown to increase bleeding complications from endoscopic procedures.^3,^5,⁶ Studies have been underpowered to detect small but potentially clinically significant effects on bleeding complication rates, however. The risk of bleeding following a specific procedure should be weighed against the risk of thromboembolic complications if antiplatelet therapy is discontinued in an individual patient.

INFORMED CONSENT

Written informed consent should be obtained before the performance of any endoscopic procedure.⁷ This consent should be obtained by the endoscopist personally and witnessed by another health care worker or family member whenever possible. The components of the informed consent process include a discussion of the benefits and alternatives to the procedure, as well as a discussion of the known risks of the procedure. The severity and frequency of complications influence the informed consent discussion; however, patient perception of risk is highly variable.⁸ The benefits and risks of sedation should always be included in the informed consent process if sedation is used. Written information about procedure-specific risks should be provided to the patient in advance of the procedure whenever possible.

COMPLICATIONS OF SEDATION

Sedation is used for most endoscopic procedures to allow a more comfortable experience for the patient and in some cases to allow a calm and still working environment for the endoscopist. Moderate (or conscious) sedation is used most commonly for GI endoscopy. By using a combination of a benzodiazepine and narcotic administered intravenously, the patient can be monitored by an assistant who is performing interruptible tasks.⁹ Deep sedation, usually achieved through the use of intravenous propofol, is being increasingly used in the United States, but risks are higher than with conscious sedation, and special monitoring and training are advisable. According to the ASA, deep sedation can be administered by non-anesthesiologists, but personnel who can rescue the patient from general anesthesia should be present.¹⁰

Several large series have demonstrated that propofol can be administered safely under the gastroenterologist’s supervision; however, additional training and monitoring with capnography are strongly recommended.¹¹^–¹⁴ Recovery times following propofol use are shorter than those following traditional conscious sedation with midazolam and fentanyl.¹⁵

Although most endoscopy can be performed safely under conscious sedation administered or supervised by the endoscopist, there are some situations in which having the assistance of an anesthesiologist or nurse anesthetist to administer deep sedation or general anesthesia can reduce the risk to the patient.¹⁶ Patients with a history of being difficult to sedate may benefit from deep sedation. This often includes alcoholic patients and those who are on high doses of narcotics. Patients with hemodynamic instability and respiratory compromise should also have special monitoring of sedative drug use.

Cardiorespiratory complications, usually attributed to sedation, are the most common complications of GI endoscopy. Survey data suggest that approximately half of endoscopic complications are in this category.^17,¹⁸ The reported frequency of cardiac and respiratory complications of endoscopy is between 2 and 5 per 1000 procedures with approximately 10% of these complications resulting in death.¹⁹ Cardiopulmonary complications as high as 11 per 1000 procedures have been reported with propofol-mediated sedation.²⁰

Respiratory complications of sedation are most commonly due to hypoventilation. Combinations of benzodiazepine and narcotics are known to produce more respiratory depression than use of either agent alone. The routine use of pulse oximetry allows more judicious titration of sedative medications but does not detect significant hypercarbia.²¹ The latter can be detected with capnography,²² but this is still not used routinely in most endoscopic facilities. Airway assessment is also important before endoscopy for the safety of the upper endoscopic procedure and for the ability to provide respiratory support should hypoventilation occur. Risk factors for airway compromise include difficulties with previous anesthesia or sedation, obesity, a small mouth or lower jaw, and a history of stridor or sleep apnea.^9,¹⁰

Hypotension is also usually due to medications. Narcotics in particular cause peripheral venous dilation and reduced cardiac preload, which in the fasting volume-depleted patient can lead to significant hypotension. This problem is usually responsive to intravenous fluid boluses, reason enough to require intravenous access during endoscopy done with sedation.⁹

Vasovagal reactions are the most common cause of cardiac arrhythmia during endoscopy. These reactions have been reported to occur in 16% of colonoscopies but can also occur with endoscopy of the upper GI tract.^23,²⁴ Reducing painful stimuli and suctioning air from the bowel are generally sufficient to reverse the vagally mediated bradycardia and hypotension; however, reversal with atropine is required for persistent bradycardia with hypotension in approximately one third of cases.²³ Self-limited ventricular arrhythmias may be seen in up to 20% of older adult patients undergoing upper endoscopy, particularly if they have electrocardiographic changes suggesting ischemia.²⁵

Careful monitoring of the patient during endoscopy helps detect cardiorespiratory complications at an early stage so that specific action can be taken. Observation of the patient by a qualified assistant who is not actively involved in performing the procedure can detect apnea and loss of consciousness.⁹ Intermittent blood pressure readings and continuous pulse oximetry are useful adjuncts and are recommended for patients receiving sedation.^9,²⁶ Although continuous monitoring of the electrocardiogram is also advisable for patients with a history of cardiac arrhythmias, routine monitoring of the electrocardiogram is not required for all patients.

The endoscopist should be familiar with specific side effects of the medications used for sedation during endoscopy (Table 40-2). In addition to commonly used benzodiazepines and narcotics, other drugs are sometimes used to augment sedation. Reversal agents for benzodiazepines (flumazenil) and narcotics (naloxone) are useful agents when oversedation occurs.

Table 40-2 Side Effects of Medications Used for Sedation, Analgesia, and Reversal

AGENT	COMMON SIDE EFFECTS OF CLASS	AGENT-SPECIFIC SIDE EFFECTS
Benzodiazepines	Respiratory depression, hypotension, cardiac arrhythmias, headache, confusion, nystagmus
Diazepam		Phlebitis and thrombosis at IV site
Midazolam		Amnesia
Narcotics (Opiates)	Respiratory depression, hypotension, urinary retention
Meperidine		Myoclonus, seizures, nausea and vomiting
Fentanyl
Topical Anesthetics	Hypersensitivity reactions, methemoglobinemia
Lidocaine
Benzocaine
Miscellaneous Agents
Propofol		Respiratory depression and arrest, hypotension, bradycardia, hyperlipidemia
Droperidol		Sedation, extrapyramidal effects, prolonged QT interval, cardiac arrest
Diphenhydramine		Sedation, nausea, dry mouth
Promethazine		Sedation, orthostatic hypotension, extrapyramidal effects, hemolytic anemia
Reversal Agents
Flumazenil*		Vasodilation, headache, seizures
Naloxone^†		Hypotension, cardiac arrhythmias, narcotic withdrawal

IV, intravenous.

* Reverses effects of benzodiazepines.

† Reverses effects of opiate narcotics.

Patients should be observed in the endoscopy unit following a procedure until they are conscious and their vital signs have returned to baseline.^9,¹⁰ Scales are available to assist staff in objectively quantifying discharge criteria.²⁷ Because sedating medications can have subtle effects on higher level mental functions for hours after administration, it is advisable to have the patient accompanied by another individual on discharge and to recommend that the patient not drive or operate machinery until the day following the procedure.⁹

INFECTIOUS COMPLICATIONS

Infections such as with Pseudomonas species or hepatitis C can be introduced by the endoscope, and are not specific to the procedure type or the patient’s underlying disease. Whereas these exogenous infections are infrequent, they merit discussion because they are usually avoidable.²⁸ Current endoscopes are highly specialized and expensive pieces of equipment that are designed to be reused. Because the GI tract is not sterile, high-level disinfection between uses is deemed to be sufficient for preventing transmission of infectious organisms between patients.^29,³⁰ The process of high-level disinfection includes mechanical cleaning of the working channels and exterior of the endoscope, followed by soaking in disinfectant solutions such as glutaraldehyde or orthophthalaldehyde, and then thorough rinsing and drying of the instruments.

Most instances of documented transmission of infection can be traced to a failure in one of the recommended steps of endoscope reprocessing.^28,^30,³¹ The estimated prevalence of transmission of infectious organisms by endoscopes is 1 in 1.8 million procedures.^30,³¹ This number may underestimate the frequency of this problem, however, because some infections may not be detected or reported. Prospective studies have not demonstrated transmission of hepatitis C by properly performed gastrointestinal endoscopy.^32,³³

High-level disinfection kills most viruses and bacteria that could contaminate endoscopes. Common blood-borne pathogens such as human immunodeficiency virus and hepatitis B and C viruses are readily inactivated by the high-level disinfection process. Although prions such as the Jakob-Creutzfeldt agent may not be inactivated by high-level disinfection, transmission of these agents by endoscopy has not been reported.²⁸

Infectious organisms may also be transmitted by endoscopic accessories or by contaminated needles and drugs used for sedation. Most endoscopic accessories are designed for single use and should be discarded following use. Reusable accessories should be sterilized after use to avoid transmitting infectious organisms.²⁹ Outbreaks of hepatitis C following endoscopy have been traced to improper sterile technique and contamination of multidose vials of sedative medications. Sterile single-use needles and intravenous tubing should always be used. Unused medication should be discarded after each procedure, and use of multidose medication vials should be discouraged.

OTHER GENERAL COMPLICATIONS

ELECTROSURGERY

Electrosurgery is the use of high-frequency electrical current to produce the controlled application of heat to tissue. Electrosurgery is used frequently in GI endoscopy to coagulate blood vessels and remove or cut tissue without inducing bleeding. Current electrosurgical generators are carefully engineered to promote patient and operator safety. Complications are infrequent but can be a result of equipment failure, operator error, or patient factors.

Electrosurgical generators are reliable devices that have long useful lives. Routine electrical maintenance and safety checks are mandatory, however. Operator error can be reduced by familiarity with the equipment being used. A large number and variety of electrosurgical generators exist, and they differ in their effect on tissue even with the same energy settings.³⁴ The dispersive electrode or ground pad should be placed in firm contact with a large skin surface to avoid skin burns.

Electrosurgery with monopolar devices causes a spark of energy when the device is activated. If sufficient concentrations of explosive gases are present, the spark may trigger an explosion. This has been reported when electrosurgery has been performed in the poorly prepared colon or following mannitol-containing laxatives in which high concentrations of hydrogen and methane may be present.³⁵

Patients who have implanted electrical devices such as cardiac pacemakers and implanted defibrillators require special considerations. In the first instance, electrocautery can inhibit cardiac pacemaker function. This can be minimized by placing the dispersive electrode well away from the pacemaker on the patient’s thigh or buttock and by using brief bursts of electrosurgical output. In the second instance, electrosurgery can cause unwanted activation of implanted cardiac defibrillators (ICDs), resulting in patient movement during endoscopic surgery and even resulting in electrical shock to the endoscopist. This is best avoided by deactivating these ICDs before electrosurgery. An external defibrillator should be immediately available if the implanted device is deactivated, and the patient’s cardiac rhythm must be continuously monitored.

MISCELLANEOUS COMPLICATIONS

Abdominal distention is usually caused by air insufflation with upper endoscopy or colonoscopy but can also be due to gas administered during laser endoscopy or argon plasma coagulation. This can cause significant discomfort and even lead to vasovagal reactions (see earlier). Care should be taken to suction air before withdrawal of the endoscope.

Although the prevalence of minor complications of endoscopy has not been well established, these problems should not be trivialized. Sore throats after upper endoscopy, pain, infections or phlebitis at intravenous catheter sites, and prolonged recovery from the effects of sedation can affect a patient’s quality of life.³⁶

TIMING AND SEVERITY OF COMPLICATIONS

Endoscopic complications can occur during the procedure itself or be delayed. Recognition of immediate complications allows prompt management of the problem and may improve the outcome of the patient. The endoscopist should have a high index of suspicion for complications of endoscopic procedures and investigate all potential problems. The value of a negative investigation should not be underestimated because this is often reassuring to the endoscopist as well as the patient.

Delayed procedural complications can be caused by late occurrence of the problem or the delayed presentation or recognition of an early complication. For example, bleeding from a colonic ulcer after polypectomy may not occur until one to two weeks after colonoscopy.³⁷ Asking the patient to watch for bloody or melenic stools and to inform the endoscopist promptly should they occur should be part of the postprocedure discharge instructions. Attributing abdominal distention to intracolonic air after a colonoscopy and not suspecting colonic perforation may lead to delayed recognition of an immediate life-threatening complication.

MEDICOLEGAL CONSIDERATIONS

Complications of endoscopy are one of the most frequent causes of malpractice suits against gastroenterologists.³⁸ Malpractice can occur if the physician does not meet his or her obligation to the patient or if the care provided does not meet the standard of care. The occurrence of a complication does not mean malpractice was committed if the procedure was properly performed and the patient was informed of potential complications of the procedure.