The control section held in the left hand has a large knob deflecting the tip vertically and a small knob deflecting laterally. Using these two knobs in combination permits tip deflection in all circumferential directions and at various angles of deflection up to slightly greater than 180° (Fig. 8.3). It is important to remember that depending on the particular endoscope in use, vigorous tip deflection may sweep quickly past the bowel lumen causing the tip to bounce from wall-to-wall making advancement difficult. Better to deflect the knobs in an unhurried and deliberate manner so as to not miss the lumen. Some endoscopists prefer to utilize the deflection knobs primarily rather than torqueing for steering the colonoscope. This requires periodic release of the insertion tube by the right hand in order to manipulate the deflection knobs with the right hand and the left thumb .

Torque is the application of a twisting force to the insertion tube of the colonoscope with the right hand. It is described as clockwise (twisting to the right) and counterclockwise (twisting to the left). When the tip is directed slightly upward or downward (using the left thumb), the application of torque has the effect of turning the colonoscope to the right or left without using the control knobs. Similarly, with slight right or left tip deflection, torque application steers up and down. Torque has the added benefit of adding a degree of “stiffness” to the insertion tube which may in turn minimize loop formation of the mobile colonic segments.

Pushing forward or insertion of the colonoscope is ultimately the maneuver that produces advancement to the cecum. However, pushing forward also stretches the colon, especially in unfixed segments, namely, the sigmoid and transverse colon. Persistence in pushing causes further elongation or stretching and eventually a loop will form in the segment. The technique of push/pull involves pushing forward followed by pulling back of the colonoscope. This has the effect of gathering or pleating of the colon over the colonoscope thereby shortening and straightening the colon (Fig. 8.4a–d).

The general rule when performing a colonoscopic procedure is to maintain visualization of the lumen at all times and to avoid the “red out” sign caused by the tip of the endoscope resting against the mucosal surface. At angulated locations or at the flexures, it may not always be possible to directly visualize the lumen despite attempts using tip deflection and torque. In these instances, the slide-by technique is utilized. The colonoscope is advanced slightly forward while steering in the anticipated direction of the lumen allowing the endoscope tip to gently slide along the mucosal surface (Fig. 8.5a). The key to this maneuver is deriving a strong impression as to which direction the lumen is truly located by visual clues. Demonstration of the site of proximal gas or liquid stool egress after suctioning provides a hint of lumen location. Anatomically, the inner circular smooth muscle of the colonic wall along with mucosal folds generates the appearance of a series of arcs visualized on the monitor (Fig. 8.5b). The imagined focal point of these arcs will point in the direction of the lumen. Slide-by is a skill that will be required and should always be performed with the utmost of caution and sensitivity for the amount of pressure exerted on the colonic wall. Any sensation of excessive force during insertion indicated by increasing resistance to insertion, stiffening of the deflection knobs, or white mucosal blanching demands withdrawal to avoid perforation.

Jiggle is produced by generating a series of rapid in and out movements with the right hand on the insertion tube. A clear lumen view is maintained at all times, and the distance of the movement is short, ordinarily 5–10 cm. The effect of jiggling is to not only shorten the colon but also encourage the endoscope to “spring” forward when there is some degree of tension inherent to the insertion tube generated by some amount of loop formation. Jiggle is different from push/pull in that the latter is typically one event consisting of a longer distance of withdrawal. I have experienced that jiggle can also be an effective means to relax spasm or persistent peristalsis typically occurring in the sigmoid colon.

Hooking is a technique designed to straighten a redundant or looped segment of colon without loss of progression of the tip of the colonoscope in the colon. As a flexure or angulation is approached, the tip of the colonoscope is deflected 90–120° to create a hook. With the “hook” held in position, the colonoscope is withdrawn a fair distance resulting in shortening the colon and loop reduction (Fig. 8.6a, b).

Insufflation using either air or CO₂ during a colonoscopic examination is essential for visualization. Because the colon is an elastic tube much like a slender balloon, continuous insufflation results in elongation—a greater anus to cecum length. Periodic suctioning in order to avoid unsuspected over distention is advised. The benefit of suction is often best seen when, after negotiating the hepatic flexure, the application of suction draws the cecum up to the tip of the colonoscope . This desired effect of suction can occur and I recommend should be applied routinely after negotiating each angulation and entering a new colonic segment.

Depression of the air/water button located on the control section held in the left hand causes water to stream across the “lens” and instill into the colon lumen. In addition, water or saline can be infused into the colon through the working channel by either syringe or a pump. Liquid infusion serves to lubricate the mucosa and facilitate tip passage, especially useful when the mucosa has a “sticky” appearance. The term water immersion colonoscopy refers to the procedure being performed during the injection of water or saline with a liquid infusion pump. In addition to lubrication, benefits include relief of spasm and straightening of the colon. The weight of the infused colon is said to “sink” to a dependent position and be less likely to elongate. Water immersion colonoscopy has been shown to decrease the time required to reach the cecum as well as reduce pain in patients receiving minimal or no sedation [3, 4].

While insertion of the tip of the colonoscope through the ileocecal valve and into the terminal ileum is not mandatory for a complete and thorough examination, it may be desirable in patients with gastrointestinal bleeding and known or suspected inflammatory bowel disease. I recommend attempt at terminal ileal intubation in the majority of procedures so as to gain and maintain the necessary skill required in those cases where ileal visualization is desired. An added benefit from making the effort at ileal intubation is the thorough evaluation of the mucosa behind the valve in the cecum, a relative “blind spot.”

The ileocecal valve is typically located 5 cm from the base of the cecum and appears as a prominent and sometimes bulbous fold. The actual orifice of the valve may not be obvious. Looking into the cecum and applying short bursts of suction often will pinpoint the valve orifice as gas or liquid stool will be seen squirting into the cecum. Intubating the valve requires passing the colonoscope tip beyond the valve into the cecum, flexing the tip 90° in the known direction of the valve and slowly withdrawing the scope (Fig. 8.7a–e). Once the tip has encountered the orifice, gentle puffs of air may help to open the valve and allow the tip to enter. More often than entering the ileum, the colonoscope tip slips off to one side or another. With skill practice, success rate will improve.