**1. Introduction**

"*Complication, in medicine, is an unfavorable evolution of a disease, a health condition or a therapy. The disease can become worse in its severity or show a higher number of signs, symptoms, or new pathological changes, become widespread throughout the body or affect other organ systems. A new disease may also appear as a complication to a previous existing disease. A medical treatment, such as drugs or surgery may produce adverse effects and/or produce new health problem(s) by itself. There‐ fore, a complication may be iatrogenic, i.e., literally brought forth by the physician. Medical knowl‐ edge about a disease, procedure or treatment usually entails a list of the most common complications, so that they can be foreseen, prevented or recognized more easily and speedily.*

*Depending on the degree of vulnerability, susceptibility, age, health status, immune system condition, etc. complications may arise more easily. Complications affect adversely the prognosis of a disease. Non-invasive and minimally invasive medical procedures usually favor fewer complications in com‐ parison to invasive ones." [1]*

A currently popular focus in the gastroenterology and endoscopic literature is the quality of colonoscopy with regard to colorectal cancer screening [2]. This includes the collection of evidence regarding the use of colonoscopy as a tool for screening programs, defining and establishing quality indicators and minimum requirements that endoscopists involved in colorectal cancer screening programs should meet, and providing evidence about proce‐ dures that may improve the quality of colonoscopy. Those who have decades of experience performing colonoscopy will be quite familiar with the myriad of complications associated with the procedure, either through their reading of the gastrointestinal endoscopy literature, from personal experience or the experience of colleagues. That being said, three major cate‐

© 2013 Miskovitz; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

gories of complications associated with colonoscopy are widely recognized. They are seda‐ tion-related complications, hemorrhage associated with colonic polypectomy and colonoscopy-related colonic perforation. Sedation-related complications are usually cardio‐ vascular and/or pulmonary and include oxygen desaturation, respiratory arrest, alterations in heart rate (bradycardia and tachycardia), cardiac arrhythmias, myocardial infarction, stroke, seizures (at times attributed to the method of preparation) and shock. Hemorrhage is most often associated with snare electrocautery polypectomy but may also occur during the performance of diagnostic colonoscopy with or without biopsies. Two general subcategories of hemorrhage exist: hemorrhage immediately following the performance of polypectomy or delayed hemorrhage occurring up to several weeks after the therapeutic procedure. Co‐ lonic perforation resulting from colonoscopy may occur due to mechanical forces exerted against the colonic wall (colonoscope tip or shaft, biopsy forceps, dilatation of a stricture), barotrauma as a result of intraluminal air or carbon dioxide insufflation, or as a result of a therapeutic procedure such as polypectomy, foreign body extraction, or stent placement to name a few. A thorough understanding of these complications, their incidence and treat‐ ment, is part of the training of all those learning to perform colonoscopy and forms the basis for the physician obtaining informed consent (an explanation of the risks and benefits of the procedure) from the patient. This chapter will systematically review our current under‐ standing of these complication categories and the methods of minimizing the likelihood of developing these complications. The latest treatments of specific complications will be re‐ viewed with the intent of aiding the physician endoscopist's understanding of the principles of risk management as regards to performing colonoscopy.

tion that since most surgical operations involve some use of force, there must be consent on the part of the patient. Because the nature of surgery is outside the experience of most pa‐ tients, the consent must be granted only after the patient is properly informed of the risks and benefits. The most famous description of informed consent is a quote from New York

The Major Complications of Colonoscopy: Sedation-Related, Hemorrhage Associated with Polypectomy and...

http://dx.doi.org/10.5772/51958

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*"Every human being of adult years and sound mind has a right to determine what shall be done with his own body; and a surgeon who performs an operation without his patient's consent commits an*

This advice is still applicable in the 21st century! Most important in considering the compli‐ cations of colonoscopy is the need to meticulously document the obtaining of informed con‐ sent from the patient and the procedural technique, findings and outcome including any

Sedation-related complications of colonoscopy are usually cardiovascular, pulmonary and oc‐ casionally neurological. The risk of these events occurring is associated with advancing age, higher American Society of Anesthesiologists Physical Status Classification System scores (ASA score—with category 6 not being applicable), and the patient's co-morbidities [6-8].

ASA-IV A patient with severe systemic disease that is a constant threat to life.

"event rate" should likely include the 30 days post procedure [10].

ASA-V A moribund patient who is not expected to survive without the operation.

ASA-VI A declared brain-dead patient whose organs are being removed for donor purposes.

ASA-E Emergency operation of any variety (used to modify one of the above classifications,

In general, patients' inpatient status, trainee participation and the routine use of supplemen‐ tal oxygen (the latter by possibly masking hypercapnea and hypoventilation) are associated with a higher risk of unplanned cardiopulmonary events [9]. The monitoring period for the

Hypoxemia, which is usually transient but often anxiety provoking for the colonoscopist, is a common occurrence during sedation for colonoscopy and has lead to the often "routine"

Justice Benjamin Cardozo who, in 1914, stated that:

**2. Sedation-related complications of colonoscopy**

ASA Physical Status Classification System (I-VI)

ASA-II A patient with mild systemic disease.

ASA-III A patient with severe systemic disease.

ASA-I A normal healthy patient.

*assault for which he is liable in damages" [4].*

complications [5].

i.e., ASA III-E)

**2.1. Hypoxemia**

*"Primum non nocere"* is the Latin phrase that means "First, do no harm". Non-maleficence, which is derived from this maxim, is one of the principal precepts of medical ethics taught to all medical students in medical school and is a fundamental principle for the provision of medical services world-wide. Another way to state it is that "given an existing problem, it may be better not to do something, or even to do nothing, than to risk causing more harm than good." It reminds the physician and other health care providers that they must consid‐ er the possible harm that any intervention might do. It is invoked when debating the use of an intervention that carries an obvious risk of harm but a less certain chance of benefit. This ancient principle should be kept in mind when contemplating colonoscopy and the possible complications of the procedure.

#### **1.1. Informed consent for colonoscopy**

The doctrine of informed consent (and its antithesis, informed refusal) for colonoscopy in‐ volves an assessment of the competence of the patient by the physician, disclosure of, in an understandable way, the information necessary to allow the patient to make an informed decision (risks and benefits considered) regarding the role of colonoscopy in his care, and the documentation of these proceedings in the medical record [3]. It is an intrinsic part of the doctor-patient relationship and an ethical obligation on the part of the physician in the clini‐ cal practice of medicine. In the United States, the doctrine of medical informed consent is most famously traced back to a 1914 New York court decision centered about the observa‐ tion that since most surgical operations involve some use of force, there must be consent on the part of the patient. Because the nature of surgery is outside the experience of most pa‐ tients, the consent must be granted only after the patient is properly informed of the risks and benefits. The most famous description of informed consent is a quote from New York Justice Benjamin Cardozo who, in 1914, stated that:

*"Every human being of adult years and sound mind has a right to determine what shall be done with his own body; and a surgeon who performs an operation without his patient's consent commits an assault for which he is liable in damages" [4].*

This advice is still applicable in the 21st century! Most important in considering the compli‐ cations of colonoscopy is the need to meticulously document the obtaining of informed con‐ sent from the patient and the procedural technique, findings and outcome including any complications [5].
