ScopeGuide-assisted Colonoscopy Versus Conventional Colonoscopy

Summary of Research Proposal

Background:

Colon and rectal cancer (CRC) is a leading cause of cancer-related morbidity and mortality in Canada. Colonoscopy is the preferred screening modality for CRC and has been shown to decrease the likelihood of developing CRC as well as CRC-related mortality, particularly through the detection and removal of potentially pre-cancerous polyps, with the aim of preventing colon cancer, and for the diagnosis of early stage CRC that is more likely to be treatable and result in long-term survival. However, recent evidence suggests that colonoscopy has not been as universally protective against CRC as had been previously hoped, particularly for proximal cancers located in the right colon. Theories as to why this might be the case include speculation about altered biology of cancers that develop in the proximal colon and technical issues relating to the performance of colonoscopy itself. In particular, one of the problems is incomplete colonoscopy that fails to examine the entire colon to the cecum, which may occur in 10-20% of cases. Furthermore, from a public health standpoint, a considerable proportion of the population remain averse to undergoing colonoscopy, particularly because of fears of procedure discomfort, decreasing the potential impact for overall CRC reduction. Thus, optimizing the technical performance of colonoscopy and improving its acceptance among patients is important for maximizing the possible benefits to society.

One of the most common reasons for incomplete colonoscopy is excessive internal looping of the endoscope. This looping has also been shown to be the major cause of patient discomfort during the procedure. Experts agree that colonoscopy is most successful at reaching the cecum and most comfortable for patients when the endoscope is kept in a straight position by minimizing loop formation and reducing loops once they have formed. Thus, identification and reduction of endoscope loops is critically important for the successful and comfortable completion of colonoscopy. Over the years, several techniques have emerged to overcome loop formation, including withdrawal of the endoscope with torque, abdominal wall pressure and patient position changes, yet these are all done in a "trial and error" fashion. Despite this limitation, these maneuvers form the cornerstones of current colonoscopy technique. Technological innovations such as smaller caliber "pediatric" colonoscopes and "variable stiffness" colonoscopes with adjustable rigidity have been introduced that have had moderate success in diminishing patient discomfort and increasing rates of colonoscopy completion. Yet despite these efforts to improve colonoscopy practice, the reality is that many procedures are still done poorly. An audit of all colonoscopies performed in Winnipeg from 2004 to 2006 demonstrated a dismal completion rate of only 65%. Thus, something more clearly needs to be done. In an effort to help improve colonoscopy from both the technical standpoint of the endoscopist and also the comfort level of patients, Olympus has redesigned a previously developed real-time imaging system that enables visualization of the shape of the entire endoscope while it is inside the patient's body. This technology, called ScopeGuide (Olympus America, Center Valley, PA), consists of electromagnetic coils embedded within the endoscope that are detected by an external receiver dish, generating a 3D representation of the endoscope that is displayed on a monitor. It is anticipated that by visualizing the entire scope as it moves through the body, endoscopists will gain useful visual information about loop formation and scope position that will enable greater technical success while creating a more comfortable patient experience.

Study Objectives:

The purpose of this project is to perform a randomized, non-blinded colonoscopy study to determine if real time visualization of the colonoscope using the new Olympus ScopeGuide system is superior to conventional colonoscopy for the achievement of endoscopic procedural outcomes and for an improved patient experience in terms of reduced discomfort and decreased sedation requirements.

Methods:

Consecutive patients referred for colonoscopy at the University of Alberta Hospital (UAH) will be considered for study enrollment. Eligible patients who meet the inclusion and exclusion criteria and who provide informed consent will be randomized to undergo conventional colonoscopy or colonoscopy with the assistance of the ScopeGuide system. The control group will use Olympus CF-H180AL variable-stiffness, high-definition colonoscopes that do not differ from the usual procedure and the investigational group will use Olympus CF-H180DL variable-stiffness, high-definition colonoscopes equipped with ScopeGuide capabilities. ScopeGuide will provide the endoscopist with a 3-dimensional image on the monitor depicting the shape of the colonoscope inside the patient's body as it moves through the colon.

The colonoscopy will be performed as clinically indicated, either with or without the aid of the ScopeGuide system. All patients will undergo a purgative bowel preparation followed by an overnight fast prior to their colonoscopy according to standard clinical practice at UAH. At the start of the colonoscopy, all patients will initially be given standardized doses of conscious sedation medications consisting of midazolam 2 mg IV and fentanyl 25 mcg IV. However, the procedure may be initiated without any sedation upon patient request. Additional doses of sedative medications may be given at patient request or when the nurse or physician believes that the patient is uncomfortable. In all cases, the endoscopist will attempt to minimize the formation of loops within the colon and will straighten those loops whenever possible. This will be achieved by conventional methods that rely on "feel" and "instinct" in the control group and will be directed by the ScopeGuide visualization in the investigational group. The endoscopist may use any technical maneuvers deemed necessary to facilitate completion of the procedure, including the application of external abdominal pressure by the nurse, the repositioning of the patient, or tightening of the variable-stiffness setting of the colonoscope. Upon intubation of the cecum, the insertion distance of the colonoscope from the anus to the cecal pole will be recorded as a marker of the straightness of the endoscope. Any abnormalities detected during colonoscope insertion will be more closely inspected, photographed and biopsied during subsequent colonoscope withdrawal. Furthermore, polyps will also be preferentially removed during colonoscope withdrawal, which is the existing standard-of-care. Any diagnostic or therapeutic applications that are required during the colonoscopy are permitted as clinically indicated.

Relevant demographic and clinical information will be recorded prior to the procedure. Additional data regarding procedural metrics, technical maneuvers, and sedation doses will be recorded during the colonoscopy. At the conclusion of the colonoscopy, the endoscopist will rate the procedural difficulty as "usual" or "difficult" and will also note the procedural diagnosis.

After the procedure, the patient will be kept in the post-endoscopy recovery area in the usual fashion. Prior to discharge home from the recovery area, participants will complete a visual analogue scale reflecting their degree of discomfort experienced during the procedure.