Class 1	Patient has no organic, physiologic, biochemical or psychiatric disturbance. The pathologic process for which the operation is to be performed is localised and does not entail systemic disturbance
Class 2	Mild to moderate systemic disturbance caused by either the condition to be treated surgically or by other pathophysiologic processes
Class 3	Severe systemic disturbance or disease from whatever cause, even though it may not be possible to define the degree of disability with finality
Class 4	Severe systemic disorders that are life-threatening, not always correctable by operation
Class 5	The moribund patient who has little chance of survival but is submitted to the operation in desperation

PROCEDURE-SPECIFIC ISSUES

Gastroscopy and endoscopic ultrasound

The main issue for gastroscopy (also known as oesophagogastroduodenoscopy [EGD] or simply ‘endoscopy’) and endoscopic ultrasound (EUS) is safety to the patient through ensuring an empty stomach. Patients should not eat solid food for at least 6 hours or clear liquids for 4 hours prior to a gastroscopy. If the patient is known to have poor gastric emptying fasting for longer or dietary restriction to clear fluids for 24–48 hours prior to the procedure should be considered. In the emergency situation, airway protection via endotracheal tube should be considered.

Specific issues arise if the patient procedure involves irradiation of the abdomen, so a history of possible pregnancy should be elicited in young and middle-aged women. If the history suggests the possibility of pregnancy, this should be checked with a serum β-hCG (human chorionic gonadotrophin).

Contrast in the bowel lumen may prevent imaging of the relevant ducts with acute upper gastrointestinal bleeding.

Preparation for upper gastrointestinal bleeding

A period of intensive resuscitation is appropriate prior to undergoing upper endoscopy, which should be performed in the presence of a health professional trained in advanced life support and airway management. If there is a suspicion that there may be significant blood in the stomach it is reasonable to give the patient a prokinetic agent (such an intravenous erythromycin) 30 min prior to the procedure.

Endoscopic retrograde cholangiopancreatography

The same considerations regarding fasting and gastroscopy apply to endoscopic retrograde cholangiopancreatography (ERCP). In addition, because ERCP is potentially a very dangerous procedure, consent issues are especially important.

For this reason, patients who have had a recent barium enema, computed tomography (CT) scan with oral contrast or enteroclysis should have a plain abdominal X-ray to ensure that the region of interest is not obscured.

ERCP involves injection of iodinated contrast into the biliary and pancreatic duct systems. It is extremely unlikely that patients with iodine allergy would have an allergic reaction in this setting. Nonetheless, many radiologists recommend a regimen for these patients such as:

• Night before procedure: 50 mg prednisone

• Day of procedure: 25 mg prednisone; 150 mg ranitidine; 25 mg promethazine.

In addition, patients with uncontrolled hyperthyroidism should avoid an iodine load. This may involve delaying the procedure or using another contrast agent such as gadolinium.

Patients with biliary obstruction should receive prophylactic antibiotics prior to the commencement of the procedure (see below for a more detailed discussion of antibiotic prophylaxis). Endoscopic sphincterotomy (ES) of the ampulla of Vater is a common procedure during ERCP. Patients in whom ES is considered should have an international noramalised ratio (INR) <1.7 (ideally normalised) and should not take IIb/IIIa inhibitors such as clopidogrel for 7–10 days if the procedure is elective. Aspirin use does not preclude ES, but ideally should also be ceased 5 days before the procedure.

Colonoscopy

Proper preparation is a prerequisite for adequate colonoscopic examination. A poorly prepared colon may lead to missed pathology and often requires repeat examination.

Two colonic purges are commonly used: polyethylene-glycol (PEG)-based solutions and sodium phosphate-based solutions. Both are osmotic, though sodium phosphate is hypertonic whereas PEG-based solutions are essentially isotonic. Sodium phosphate purges have the advantage of requiring a smaller volume to be consumed (as they draw water into the bowel by osmotic pressure). This smaller ingested volume leads to better compliance. However, this may cause dangerous dehydration or electrolyte imbalances such as hyperphosphataemia. This is especially a concern in elderly patients or those with renal impairment. Furthermore, sodium phosphate purges may cause mild inflammation of the colonic mucosa and sometimes small aphthous ulcers. Therefore this type of purge is best avoided in patients undergoing colonoscopy to assess inflammatory bowel disease. PEG-based solutions cause less fluid and electrolyte disturbance, but may be difficult to ingest due to their large volume (3–4 litres). Only approximately 80% of patients complete a PEG-based purge.

Stimulant purgatives such as senna are not effective as sole agents and are rarely used. Fermentation of osmotic sugar purgatives such as mannitol, sorbitol and lactulose by gut bacteria may lead to high colonic concentrations of hydrogen gas. This can cause explosion if electrical current is used for polypectomy and, therefore, must not be used for colonoscopic preparation.

Patients should fast for at least 6 hours prior to colonoscopy since sedation associated with the procedure decreases protective reflexes and raises the possibility of aspiration of gastric contents.

Preparation for lower gastrointestinal bleeding

Acute massive haematochezia should be investigated with colonoscopy following a rapid purge. This usually involves at least 3–4 L PEG-based solution, until the effluent is pink. In patients unable to drink the solution, it may be administered using a nasogastric tube. A prokinetic agent may be helpful to speed this process. It should be noted that the passage of bright red blood per rectum in a haemodynamically unstable patient could be due to a duodenal source of bleeding, so these patients will often have an emergency upper endoscopy first.

Flexible sigmoidoscopy

One or two enemas are usually sufficient preparation just prior to flexible sigmoidoscopy. Often, no preparation is used if the procedure is performed for the investigation of acute diarrhoea. Fasting is not required unless the patient requires sedation (which is unusual).

PATIENT-SPECIFIC ISSUES

General considerations

Patients usually take their normal medications several hours prior to endoscopic procedures with a sip of water. Exceptions are drugs which are potentially harmful to the oesophagus if lodged there (such as bisphosphonates, potassium supplements, non-steroidal antiinflammatory drugs and tetracycline). Patients on bronchodilator therapy should be encouraged to bring their puffers to the hospital with them.

Diabetes mellitus

Medication for patients with diabetes requires special consideration. There are no controlled trials to guide management, but, generally, patients on oral hypoglycaemic agents omit their morning dose, while patients on insulin usually halve their morning dose. Close attention must be paid to the patient’s blood glucose level during procedure preparation, before the procedure and after. Patients with diabetes should be first on the morning endoscopy list in order to minimise disturbance to their regimen and reduce fasting time.

Anticoagulant medications

The American Society for Gastrointestinal Endoscopy has published excellent guidelines for anticoagulant therapy. These are summarised in Table 28.2. In brief:

• Aspirin. There is no evidence that therapeutic endoscopic procedures (such as polypectomy and biliary sphincterotomy) cannot be performed on low-dose aspirin. Thus, use of aspirin in the preceding 5 days should not lead to cancelling the procedure. Nonetheless, most practitioners would cease aspirin 5–7 days prior to an elective procedure.

• New antiplatelet agents. There is little data on which to base recommendations. In general, these drugs cause more profound platelet inhibition than aspirin and should be ceased 7–10 days prior to high-risk elective procedures (such as colonoscopy with polypectomy or biliary sphincterotomy, oesophageal dilation, etc). An important caveat is the patient on clopidogrel with a drug-eluting coronary stent. These patients are at risk of acute stent thrombosis, infarction and possibly death if their antiplatelet drugs are ceased. Management of these patients should be individualised in collaboration with their cardiologist.

• Warfarin. Safe therapeutic endoscopy can be performed with an INR <1.7. Diagnostic endoscopic procedures can be safely performed with a therapeutic INR. If a therapeutic procedure (polypectomy, biliary sphincterotomy, etc) is likely, the INR should be <1.7 prior to the procedure. The management of cessation of warfarin (i.e. whether the patient requires heparin cover and, if so, which type) depends upon the individual lesion and is best managed in collaboration with the patient’s cardiologist.

• When to restart anticoagulation. There are few endoscopic data to guide practice and the decision depends partly upon the indication for anticoagulation (see Table 28.2). It is important to note that although most post-procedure bleeding occurs within 72 h of the procedure, delayed haemorrhage may occur up to 3 weeks after the procedure.

Table 28.2 The Amercian Society for Gastrointestinal Endoscopy guidelines on anticoagulants in patients undergoing endoscopic procedures

Acute gastrointestinal haemorrhage in the anticoagulated patient:

• The decision to reverse anticoagulation and the extent of anticoagulation reversal should be individualised, weighing the risk of thromboembolism against the risk of continued bleeding

• A supratherapeutic INR may be corrected with infusion of fresh frozen plasma

• Correction of the INR to 1.5–2.5 permits effective endoscopic diagnosis and therapy

• Reinstitution of anticoagulation should be individualised

Procedure risk	Condition risk for thromboembolism
	High	Low
High	Discontinue warfarin 3–5 days before procedure	Discontinue warfarin 3–5 days before procedure
	Consider heparin while INR is below therapeutic level	Reinstitute warfarin after procedure
Low	No change in anticoagulation. Elective procedures should be delayed while INR is in supratherapeutic range
	Aspirin and other non-steroidal antiinflammatory drug (NSAID) use
	In the absence of a preexisting bleeding disorder, endoscopic procedures may be performed in patients taking aspirin or other NSAIDs

INR = international normalised ratio.

From Gastrointest Endosc 1998;48:672–5, with permission.

There is very little scientific evidence to guide practice. Excellent guidelines are available from the American Society for Gastrointestinal Endoscopy, which are summarised in Table 28.3. In brief, endoscopic procedures can be divided into high and low risk of significant bacteraemia and patient factors can similarly be classed in terms of risk from bacteremia. Low-risk procedures (such as gastroscopy and colonoscopy with or without polypectomy) never mandate the use of antibiotics, but they may be used at the clinician’s discretion. High-risk patients (e.g. those with prosthetic heart valves, previous endocarditis, recent vascular graft) undergoing a high-risk procedure (such as oesophageal dilation or sclerosis of varices) used to require antibiotics but this is not longer recommended routinely. All other permutations of patient and procedure are guided by physician preference. When there is doubt, most clinicians take a pragmatic approach and give prophylactic antibiotics.

Table 28.3 The American Society for Gastrointestinal Endoscopy guidelines on management of antibiotics in patients undergoing endoscopic procedures

Patient condition	Procedure contemplated	Antibiotic prophylaxis
High risk: • Prosthetic valve • History of endocarditis • Systemic pulmonary shunt • Synthetic vascular graft >1 year old • Complex cyanotic congenital heart disease • Moderate risk: • Most other congenital abnormalities • Acquired valvular dysfunction (e.g. rheumatic heart disease) • Hypertrophic cardiomyopathy • Mitral valve prolapse with regurgitation or thickened leaflets

Stricture dilation Recommended Variceal sclerotherapy ERCP/obstructed biliary tree Other endoscopic procedures, including EGD and colonoscopy (with or without biopsy/polypectomy), variceal ligation Prophylaxis optional Oesophageal stricture dilation Prophylaxis optional

Variceal sclerotherapy Other endoscopic procedures, including oesophagogastroduodenoscopy and colonoscopy (with or without biopsy/polypectomy), variceal ligation Not recommended Low risk:

Other cardiac conditions (CABG, repaired septal defect or patent ductus, mitral valve prolapse without valvular regurgitation, isolated secundum atrial septal defect, physiologic/functional/innocent heart murmurs, rheumatic fever without valvular dysfunction, pacemakers, implantable defibrillators)

All endoscopic procedures Not recommended Obstructed bile duct ERCP Recommended Pancreatic cystic lesion ERCP, EUS-FNA Recommended Cirrhosis acute gastrointestinal bleed All endoscopic procedures Recommended Ascites, immunocompromised patient Stricture dilation Not recommended Variceal sclerotherapy Not recommended

Other endoscopic procedures, including EGD and colonoscopy (with or without biopsy/polypectomy), variceal ligation All patients Percutaneous endoscopic feeding tube placement Recommended (parenteral cephalosporin or equivalent) Prosthetic joints All endoscopic procedures Not recommended Cardiac prophylaxis regimens (oral 1 h before, IM or IV 30 min before procedure) Amoxycillin by mouth or ampicillin IV: adult 2.0 g, child 50 mg/kg Penicillin allergic: clindamycin (adult 600 mg, child 20 mg/kg) or cephalexin or cefadroxil (adult 2.0 g, child 50 mg/kg), or azithromycin or clarithromycin (adult 500 mg, child 15 mg/kg), or cefazolin (adult 1.0 g, child 25 mg/kg IV or IM), or vancomycin (adult 1.0 g, child 10–20 mg/kg IV)

CABG = coronary artery bypass graft; ERCP = endoscopic retrograde cholangiopancreatography; EUS-FNA = endoscopic ultrasound guided fine needle aspiration; IM = intramuscular; IV = intravenous.

From Hirota WK, Petersen K, Baron TH, et al. Guidelines for antibiotic prophylaxis for gastrointestinal endoscopy. Gastrointest Endosc 2003; 58:475–82, with permission.

Due to the high risk of significant infective complications, prophylactic antibiotics are recommended for all patients undergoing some specific endoscopic procedures. These are:

• Percutaneous endoscopic gastrostomy (PEG) insertion

• Endoscopic pseudocyst drainage

• ERCP in the presence of biliary obstruction

• EUS-guided puncture of cystic lesions

• Any procedure in the bleeding patient with decompensated liver disease.

The choice of antibiotic should be dictated by protocols determined by the infectious diseases unit of the institution.