Patient Preparation and Pharmacotherapeutic Considerations

Introduction

Correct patient preparation is essential for all endoscopic procedures because it contributes significantly to the safety and success of the procedure. Many requirements must be considered during the preparatory phase; patient preparation is not limited to statements regarding fasting or how to complete a bowel preparation. The clinician must consider issues such as timing and patient-specific factors that must be taken into account when preparing for an endoscopic procedure. If the patient has had this type of information explained, he or she is more likely to comply with preparation instructions in a safe manner. As part of this phase and as part of the explanation about what the procedure involves, it is also necessary to explain potential risks and complications. All this communication with the patient contributes to the process of obtaining informed consent, which is a crucial part of the preparation process.

Informed Consent

The process of informed consent varies from country to country. In many parts of Europe, a formal consent is not required before endoscopic examinations. If the patient comes to have the procedure performed, these systems assume an implied consent. In other parts of the world, such as the United States and Australia, the consent process is a very detailed and potentially complex process that requires considerable attention by the endoscopist (see Chapter 10 ).

General Information About Patient Preparation

Numerous aspects must be considered when preparing patients for endoscopic examinations, including the following:

• Understanding of the patient's particular clinical problem

• Awareness of the patient's clinical history

• Knowledge of the patient's recent (and past) medication history

• Requirements of procedure-specific preparation

• Requirements of patient-specific preparation

• Informed consent

• Postprocedure observation and discharge planning

The endoscopist must have knowledge of the indication for the procedure because this determines not only what procedure is performed but also what interventions or treatment might be required during the procedure. Implicit also is an understanding of the patient's clinical history and the results of any recent investigations. The preprocedure assessment must extend to the patient's past medical and surgical history, previous endoscopy results, current medical therapy (including over-the-counter and intermittent medications), and drug allergies. Specific clinical history such as diabetes, a personal or family history of bleeding disorder, anesthetic reactions, or previous adverse reactions to other medical interventions (including reactions to radiologic contrast agents) should also be considered. Armed with this information, the endoscopist is able to determine the proper preparation and any specific modifications regarding sedation that might be required for the individual patient (see Chapter 7 ).

After the procedure preparation, risks, and potential complications have been discussed, the next phase of the explanatory process is to discuss discharge guidelines. Most endoscopic examinations are performed as day procedures, and frequently patient sedation is administered. Most institutions require that sedated patients are discharged in the care of a responsible person who not only can supervise transportation of the patient home but who also is able to respond to any delayed complications or difficulties. The level of postprocedure supervision depends on the type of intervention and sedation, specific patient factors such as mobility and age, and other factors such as geographic isolation. These issues must be brought to the patient's attention before the procedure so that proper planning can occur. Difficulties with discharge arrangements should always be resolved before the endoscopic procedure and never left to be discussed after the procedure has been performed. Although the previous process may seem cumbersome, there are significant advantages for the patient and the endoscopist, such as the following:

• Ability to obtain informed consent

• Proper patient preparation

• Greater patient confidence with preparation

• Decreased failure of patient to attend endoscopic examination

• Correct procedure being performed

• Improved diagnostic yield

• Decreased patient anxiety and potentially improved patient tolerance of the procedure

• Improved discharge outcome

Routine Laboratory Testing Before Endoscopic Procedures

Routine preprocedure laboratory testing is the practice of ordering a set panel of tests for all patients undergoing a given procedure, irrespective of specific information obtained from the history and physical examination. There are insufficient data to determine the benefit of routine laboratory testing before endoscopic procedures. Most studies indicate that physicians overuse laboratory testing and that routine preoperative screening tests are usually unnecessary. In one large study, only 40% of preoperative tests were done for a recognizable indication, and less than 1% of the tests revealed abnormalities that would have potentially influenced perioperative management. Moreover, no adverse events were attributable to the identified laboratory abnormalities. An evaluation of routine laboratory testing in the periendoscopic period should consider the frequency of abnormal test results within a given population, the accuracy of the tests, the risks of the planned procedure, the use of moderate sedation versus anesthesia, and whether an abnormal result will affect the decision to perform endoscopy or alter periprocedural management or outcome. Individual patient and procedure risks should be factored into the decision to perform periendoscopic laboratory tests. The cost of screening and the expense of follow-up testing to evaluate often minor abnormalities that seldom improve patient care must also be considered. Furthermore, falsely abnormal test results may unnecessarily delay endoscopy and subject the patient to additional risks, with untoward health and economic consequences.

Preparation for Endoscopy and Enteroscopy

Patients should not eat solid food for 6 to 8 hours or drink clear fluids for at 2 to 4 hours before an elective endoscopy. If a delay in gastric emptying is known or suspected, longer fasting or a period of a fluid-only diet should be considered. Many centers use prokinetic agents to speed gastric emptying in patients when fasting time is inadequate (see subsequent section on special circumstances ). In situations in which there is a delay in gastric emptying or in which there is inadequate fasting time, there is a significant risk of pulmonary aspiration, and airway protection with airway intubation should be considered. Normally, it is acceptable for patients to take their usual medicines with a sip of water before endoscopy. Special consideration must be given to patients taking anticoagulant medication or medication to treat diabetes (see subsequent section on Special Circumstances).

If a bleeding disorder is suspected or known, tests to evaluate this and direct therapy are indicated. Similarly, if the patient's clinical condition is unstable or indicates that an abnormality in the blood tests is likely to be present, appropriate testing and correction of relevant abnormalities is indicated. Preparation for antegrade enteroscopy is the same as described earlier. If retrograde enteroscopy is to be performed, preparation requirements are the same as for colonoscopy.

Preparation for Endoscopic Retrograde Cholangiopancreatography

The preparation of patients for endoscopic retrograde cholangiopancreatography (ERCP) is similar to the preparation for endoscopy. Generally, patients undergoing ERCP almost always require sedation and the duration of the procedure is longer; this should be taken into account for purposes of discharge planning. Patients with suspected or proven biliary or pancreatic duct obstruction are generally given prophylactic intravenous antibiotics if there is a clinical suspicion of inadequate duct drainage ( Table 8.1 ). Antibiotics may also be given in patients with sclerosing cholangitis and in patients after liver transplantation. Before ERCP, it is important to determine if the patient has a known history of reaction to iodinated contrast agents. Although reaction to the contrast agent in allergic patients during ERCP is rare, it is generally considered appropriate to administer prophylactic steroids, often in combination with an intravenous antihistamine agent. In severe cases, enlisting support of an anesthetist in case of a reaction is a prudent precaution. The use of a noniodinated contrast agent is an additional strategy.

Because ERCP is performed with radiologic imaging of the abdomen, patients who have had recent barium studies or other oral contrast agents should be checked to ensure that the field of view is clear for the ERCP to be successfully completed. If there is residual contrast material in the gut, a formal bowel preparation may be required. Women of childbearing age must be asked if they are pregnant. If there is uncertainty, the ERCP may need to be deferred until a pregnancy test can be done. If ERCP is considered necessary in a pregnant woman, appropriate lead shielding of the lower abdomen is recommended to protect the fetus. Similarly, pelvic shielding is appropriate for any premenopausal woman.

No data support routine blood tests before diagnostic ERCP, and screening tests are generally not required. If a bleeding disorder is suspected or known, tests to evaluate this and direct therapy are indicated. Similarly, if the patient's clinical condition is unstable or indicates that an abnormality in the blood tests is likely to be present, appropriate testing and correction of relevant abnormalities is indicated. In patients presenting for ERCP with a history or signs of biliary obstruction, the possibility of disordered coagulation exists. Correction of this type of abnormality before the procedure is appropriate.

The European Society of Gastrointestinal Endoscopy now recommends routine rectal administration of 100 mg of diclofenac or indomethacin immediately before (or after) in all patients without contraindication to the medication.

Preparation for Colonoscopy

Of all endoscopic procedures, the quality of the preparation before colonoscopy has the greatest effect on the outcome of the procedure. The preparation is often regarded as the most unpleasant part of colonoscopy, and many patients are more concerned about this aspect than having the procedure performed. It is vital that the patient be given detailed verbal and written instructions to complete the preparation safely. If the correct preparation is not followed, the procedure usually has to be deferred. Good bowel preparation is essential to provide an optimal view for colonic examination and to minimize the risk of colonic trauma during the procedure resulting from a poor view. The method of administration and types of bowel preparation are discussed in detail in the next chapter ( Chapter 9 ).

To achieve an optimal preparation, a careful patient assessment is needed to determine which bowel cleansing agent should be used and what modifications to the patient's diet and regular medications are required. The addition of simethicone to the bowel preparation does not improve cleansing but does reduce bubbles, which may improve the endoscopic view. As part of the preparation, most patients are advised to have only a clear liquid diet for 24 hours before the examination. Routine blood testing before colonoscopy is not required. Management of patients taking antiplatelet and anticoagulation medications should be carefully considered before the examination to minimize the risk of procedure-related bleeding (see later guidelines). In addition, any medication that might be associated with constipation should be temporarily stopped to facilitate the bowel cleansing process. In particular, oral iron can make the stool black and viscous, and iron should be stopped at least 5 days before the colonoscopy. Last, specific instructions should be given to diabetic patients who are taking oral hypoglycemic medications or insulin to avoid periprocedural hypoglycemia.

Intravenous sedation is administered to most patients who undergo colonoscopy. It is necessary for the patient to fast before the procedure to reduce the potential for aspiration. The duration of fasting can be comparatively brief because the patient will have been on clear fluids only for 24 hours before the procedure while undergoing bowel preparation. A fasting time of 2 to 4 hours is generally considered adequate.

There are many independent predictors for a potential inadequate bowel preparation, such as a late colonoscopy start time; failure to follow preparation instructions; inpatient status; procedural indication of constipation; use of drugs that impair gut motility (e.g., tricyclic antidepressants, calcium channel blockers, iron); male gender; and a history of cirrhosis, stroke, dementia, obesity, or diabetes mellitus. A prior history of failed colonoscopy preparation is also highly predictive of a failed second or subsequent attempt at preparation. In these various patient groups, a more prolonged bowel preparation may be required. Other options to improve the quality of the preparation include abstinence from dietary fat for 1 week and a morning procedure time. In patients who develop nausea, vomiting, or excessive bloating and patients who do not tolerate the preparation, one of the following measures can be used:

• Stop the preparation early if a clear fecal fluid output is achieved

• Interrupt the preparation temporarily for 1 to 2 hours and then resume

• Use a trial dose of metoclopramide or another prokinetic agent

• Chill the bowel preparation solution (very cold solution is not recommended)

• Add clear, sugar-free flavor enhancers or lemon juice (avoid red colors)

• Slow the rate of consumption of the solution

Preparation for Flexible Sigmoidoscopy

Preparation before flexible sigmoidoscopy generally requires cleansing of only the left colon. In most cases, this cleansing can be achieved by administering one or two enemas 1 hour before the procedure. Several types of enemas are available:

• Microlax enema (sodium citrate 450 mg, sodium lauryl sulfoacetate 45 mg, and sorbitol 3.125 g)

• Fleet enema (sodium phosphate)

• Tap water enema

• G&O enema (three parts glycerin, three parts olive oil, and three parts water)

A more extensive bowel preparation may be required in severely constipated patients or in patients in whom a therapeutic procedure is required, such as polypectomy or argon plasma coagulation therapy. In these cases, 2 L of polyethylene glycol (PEG)-based bowel preparation with 24 hours of clear fluid may be adequate. In contrast, bowel preparation may be unnecessary in patients with active colitis or watery diarrhea. Generally, patients undergoing flexible sigmoidoscopy do not require intravenous sedation. If sedation is required, the patient should be advised to follow a protocol similar to other endoscopic procedures requiring sedation.

Preparation for Endoscopic Ultrasound

Patient preparation for endoscopic ultrasound (EUS), including the dietary guidelines, is similar to preparation for upper gastrointestinal (GI) endoscopy. In patients in whom a biopsy or therapeutic intervention is considered necessary, a platelet count and coagulation studies may be appropriate before the procedure if a bleeding disorder is suspected. In addition, antiplatelet and anticoagulation therapies must be reviewed, and if EUS-guided biopsy is likely to be performed, appropriate modification or cessation of these agents is necessary given that EUS-fine-needle aspiration (FNA) is a high-risk procedure for bleeding (see later discussion). Diagnostic EUS is considered a low-risk procedure and thus antiplatelet and anticoagulation therapies can be continued. For those who are on double-antiplatelet therapy for coronary stent(s), EUS-FNA can be performed with cessation of clopidogrel but continuation of aspirin. A 2017 retrospective study indicated that the risk of bleeding in patients who underwent EUS-FNA while on aspirin was not significantly higher than those without aspirin use (1.6% vs. 1.0%).

Antibiotic prophylaxis is not generally required unless FNA of a cystic lesion or fiducial insertion is being performed (see Table 8.1 ). FNA of cystic lesions is considered high risk for infection, and antibiotics are recommended. Available limited data indicated that the risk of infection after fiducial placement varies between 0.6% and 1.6%. Given the inability to remove these markers after implantation, antibiotic prophylaxis is generally recommended and adopted by most centers. In contrast, FNA of solid lesions in the upper GI tract or in the lower GI tract has been shown to be a low-risk procedure and does not warrant antibiotic prophylaxis. The use of antibiotic prophylaxis in EUS-guided celiac plexus block or neurolysis has not been established, as infectious complications after this procedure are rare.

Preparation for Capsule Endoscopy

Optimizing conditions for capsule endoscopy continues to be an area of interest. Most centers prefer a slightly longer fasting time than for routine endoscopy. Generally, clear fluids are given after lunch on the day before the examination, and the patient fasts for 12 hours before the examination is scheduled to begin. No medication should be taken within 2 hours of ingestion of the capsule. In some centers, 2 L of a PEG-based bowel preparation regimen is given before the patient begins the 12-hour fast. This additional step might be particularly important if the patient has had a recent barium study or has had some other form of oral radiologic contrast agent. Some units ask the patient to ingest a small amount of simethicone preparation before the procedure to improve visual quality, as well as a prokinetic such as metoclopramide. The use of a purgative preparation may improve the quality of the small bowel images obtained during the capsule endoscopy study and increase the diagnostic yield. This benefit has not been confirmed in other studies. The purgative preparation does not seem to influence completion rate of the study, however. The optimal preparation regimen is not yet established, so instructions may be individualized for the patient. It is prudent to review the patient's medications and consider withholding any medication that might slow GI motility. Iron supplements should be stopped at least 3 days before the examination.

Preparation for Endoscopic Procedures in Patients With Diabetes

There are no controlled trials to guide preparation for endoscopic procedures in diabetic patients. The approach to these patients must be individualized, and factors such as usual glycemic control and the patient's ability to manage his or her diabetes are important considerations. There are no specific requirements in diabetic patients who are controlled on diet alone. In patients taking oral hypoglycemic agents, medications are generally withheld during preparation for the procedure. During this time, the patient must monitor his or her serum glucose and be able to manage or get assistance if there is evidence of progressive hyperglycemia. Hypoglycemia is managed with sugar-containing clear fluids or candy. In patients taking insulin, dose reduction while undergoing the preparation is normal. For upper GI procedures, the usual dose may be given the evening before the procedure, but only half the dose is given on the morning of the examination. The remaining dose can be given, if appropriate, after the procedure has been completed.

Insulin-dependent diabetics undergoing preparation for colonoscopy should have their diabetic treatment individually modified with clear instructions provided as to how hypoglycemia and hyperglycemia should be managed. Diabetic patients should preferentially be scheduled for a morning procedure and ideally be the first case for the day. During the preparation, the patient must be advised to monitor serum glucose regularly. Patients with brittle diabetic control, patients unable to manage hypoglycemia or hyperglycemia, and patients with significant other comorbidity may need medical or nursing supervision during bowel preparation.