Top 10 mistakes during colonoscopy by trainees?

Here is my list of the top 10 mistakes made by residents and fellows when they attempt to insert a colonoscope. While there are several other mistakes that trainees make, these are the most common. They all interrupt the course of colonoscopy, and stop the acquisition of a smooth technique.

The 10 MOST COMMON MISTAKES BY TRAINEES

1. Losing the lumen

Once you lose the lumen, further insertion is unwise /impossible. You must pull back until you see the lumen, or at least get a hint of where it is. With very acute bends it is acceptable to use the “slide by” technique where you determine the direction of the lumen by the light reflections on the wall of the bowel. Deflect the scope maximally in that direction and push gently. If the mucosa moves past the lens you are OK. If the mucosa stops moving, stop pushing. However, remember that you are creating a loop that will have to be reduced once the scope is stabilized. Push past the loop a little way and then try withdrawing with torque…first in one direction and then the other (if the first direction doesn’t work).

2. Not avoiding loops

The basic principle of colonoscopy is to shorten the colon over the colonoscope so that 6 feet of bowel are examined by 2.5 feet of scope. Loops, particularly in the sigmoid and transverse colons, and at both flexures, prevent colonic shortening. If you feel a loop is forming, you can splint the loop by pushing on it. Directed pressure on the apex of the loop is important. (Guidance at preventing loops will be presented in another episode). Another common cause of loop formation is bringing right and left hands together to work the tip deflection control knobs with the same hand that is holding the scope. This is almost guaranteed to create a loop. Try to keep your right and left hands separated during insertion; the right pushes and pulls, torques, jiggles and twists: the left deflects the tip, gets suction and irrigation.

3. Not recognizing loops

Inserting the colon through a loop usually expands the loop, causing pain for the patient, and paradoxical movement in the scope. When you push more scope in, you lose ground, and when you pull scope out, you gain. Pushing through a loop should be the last resort, after everything else has been tried. “Everything else” includes withdrawing until the scope is straight and reinserting while doing something to prevent the loop: such as splinting a palpable loop, turning the patient to the side or prone, asking the patient to hold breathe, decompressing the lumen, using torque or reverse torque. If that doesn’t work, pull back and try again, doing something different. Sometimes it takes a few tries, gaining an inch each try, until it finally goes.

4. Not pulling back enough

There is often a reluctance to pull the scope back far enough to straighten the loop. This is unfortunate and just makes the procedure longer than it must be.

5. Putting too much gas in

It is tempting for novice colonoscopists to fill the colon with gas, especially when the colon is spasming and reluctant to distend. This typically happens in the sigmoid colon. The result is that the colon unnecessarily elongates, accentuating loops and making the patient feel bloated. It is preferable to wait for spasm to go away by itself (which it will) or use some warm water irrigation if the spasm is persistent. (the water should be “blood heat”, which is surprisingly warm).

6. Not aspirating gas

This is the corollary of 5. One way to advance the scope without inserting any of its length into the anus is to suck the colon over the scope. This is effective in “floppy” parts of the colon such as the transverse and the ascending colon. Aspirating gas should be done regularly to avoid “the bloat”, and aspirating gas just prior to biopsy puts the mucosa into folds and makes sure you get a decent chunk of tissue in the forceps.

7. Sucking mucosa into suction channel

Sucking mucosa into the suction channel is perhaps the biggest “waste of time” maneuver during colonoscopy. If this happens you can either pull back the scope until the mucosa is disengaged (thereby losing hard-won ground) or remove the suction button (releasing the trapped mucosa instantly). It better to avoid sucking up mucosa in the first place, and this depends on stopping sucking before the mucosa gets trapped. You can set yourself up for success by making the sure the meniscus of the fluid you want to aspirate is at the 6 o’clock position in the scope. This is where the suction channel is placed, and so sucking liquid will be much more efficient.

8. Not watching the patient

It is important to keep your eye on the patient, especially when you are scoping with conscious sedation. Some patients are very brave and may be lying there not saying anything but sweating and grimacing with pain. Other patients may be quietly having a vaso-vagal reaction. The nurse should also be watching the patient but you have an important role to play. Ignoring the patient usually happens during very difficult exams when all your concentration goes into the scope itself and the monitor. You should be intentional about glancing at the patient from time to time.

9. Being too rough

This is a similar problem to 8, in that colonoscopy can be very frustrating and it is tempting to take your frustrations out on the scope. This cannot happen. Stop. Take a break for a few minutes. Ask for help. Start again. Accept an incompletion. These are all good alternatives.

10. Trying the same unsuccessful maneuver over and over again.

There are many reasons why the colonoscope will refuse to pass a section of the colon. Formation of a loop is the most common. Intense spasm, lack of length of the scope (you pushed it all in and you only reached the mid transverse), a hairpin bend, severe diverticulosis, pain…are others. Before giving up it is reasonable to pull back and gently try again. However, you should always do something a little different. This may be to torque in a different direction; to change the patient’s position; to give more medication; to aspirate air; to use hot water irrigation; to feel for loops in the typical positions and splint them. Doing something that doesn’t work and then repeating it makes little sense.